Negative Surges in the Southern Baltic Sea

Size: px
Start display at page:

Download "Negative Surges in the Southern Baltic Sea"

Transcription

1 ISSN Negative Surges in the Southern Baltic Sea (Western and Central Parts) Berichte des BSH 45

2 Negative Surges in the Southern Baltic Sea (Western and Central Parts) Authors: Marzenna Sztobryn Bärbel Weidig Ida Stanisławczyk Jürgen Holfort Beata Kowalska Monika Mykita Alicja Kańska Katarzyna Krzysztofik Ines Perlet Berichte des Bundesamtes für Seeschifffahrt und Hydrographie Nr. 45/2009

3 In der Reihe Berichte des Bundesamtes für Seeschifffahrt und Hydrographie werden Themen mit Dokumentationscharakter aus allen Bereichen des BSH veröffentlicht. Durch die Publikation nimmt das BSH zu den Inhalten der Beiträge keine Stellung. Die Veröffentlichungen in dieser Berichtsreihe erscheinen nach Bedarf. Negative Surges in the Southern Baltic Sea (Western and Central Parts) (Menü: Produkte R Bücher R Berichte des BSH) Bundesamt für Seeschifffahrt und Hydrographie (BSH) Hamburg und Rostock ISSN-Nr Alle Rechte vorbehalten. Kein Teil dieses Werkes darf ohne ausdrückliche schriftliche Genehmigung des BSH reproduziert oder unter Verwendung elektronischer Systeme verarbeitet, vervielfältigt oder verbreitet werden.

4 Abstract The characteristics of negative surges (water levels below 440 cm) in the southern Baltic Sea are described using data from five gauge stations along the German and Polish coasts. The stations are Wismar, Warnemünde, and Sassnitz in the German part of the Baltic coast, Świnoujście and Kołobrzeg in the Polish part. Hourly and 4-hourly data series starting in 1958 are available from these stations. Besides, 20 major negative surge events observed in the period from 1955 to 2005 and the meteorological situation leading to these events are discussed in detail. The most important factor leading to the development of a negative surge is strong offshore wind or storm forcing the water away from the coast. Wind measurements on the coast have shown that offshore wind, i. e. wind from ESE- WSW directions, prevailed in a large majority of all negative surge events observed (about 90 %). Strong offshore wind normally accompanies low-pressure systems tracking rapidly across the Baltic Sea. The majority of all negative surges on record (83.6 %) occurred under zonal circulation conditions. Among these, at 32.5 %, the West Cyclonic atmospheric situation (Wz) was most frequent, followed by the Central European Ridge situation (BM), at (14.8 %), and the cyclonic North-West Cyclonic situation (NWz), at 10 %. The severity and frequency of negative surge events decreases from west to east, which is explained by the fact that the southern Baltic Sea has the shape of a bay with an eastward opening. Statistically, a negative surge event with water levels of 190 cm occurs every 50 years in Wismar, whereas only 128 cm has to be expected in Kołobrzeg. Wismar also is the only station where negative surge events have occurred in each month of the year, although the majority of such events occur during the winter months.

5

6 1. Introduction Background Brief review of scientific contributions Geographic and hydrodynamic background Data and definition Data Definition and general characteristics of negative surges Seasonal and long term variation Interannual variation Seasonal distribution Long-term statistics Meteorological factors contributing to negative surges Strong offshore wind on the coast Offshore storm surges in the wind field of a moving depression High pressure system as low sea level generator Co-occurrence of atmospheric situations over Europe and negative surges at the southern coast of the Baltic Sea Most severe negative surges on the southern Baltic Sea coast November January January February December October March January November November November January February January February December November December January References Figure Index Table Index Acronyms Authors... 68

7

8 Introduction 7 1. Introduction 1.1. Background Extreme oscillations of coastal sea levels pose a threat to the national economy and ecology of many countries. Considerable technical and scientific effort has been invested worldwide to reduce the impacts of such phenomena, which may reach catastrophic proportions. Storm surges are water level extremes which have been investigated quite extensively because they represent a major threat to the coastal population. By contrast, the existing body of research on extremely low water levels, so-called negative surges, is much smaller. As negative surges may cause small harbours to fall dry and obstruct navigation in general, an understanding of negative surges is crucial to the safety and efficiency of navigation. Future ships will be larger and have deeper draughts, and sailing times to and from harbours will be reduced further in order to save costs. Also the loading rate is a very important factor for shipping companies. Ferry traffic of course depends on water levels, and shipyards need enough water for docking and undocking. To ensure the safety of navigation in the difficult waters of the southern Baltic Sea, reliable water level data are essential, particularly in case of negative surges. The present study of negative surge events in the western and central parts of the southern Baltic Sea coast has been prepared by the Polish/ German W-1 Group on Hydrology and Hydrogeology in the Polish/German boundary waters and is a sequel to a co-operative study of historical storm surges that have occurred on the same coast, which was completed in However, the period covered by the present study is five years longer than that of the first study. The project was implemented jointly by Bundesamt für Seeschifffahrt und Hydrographie Hamburg Rostock (BSH), Germany, and Instytut Meteorologii i Gospodarki Wodnej, Oddział Morski (IMGW OM), Poland. In the first part of the monograph, the phenomenon of negative surges in the western and central parts of the southern Baltic Sea coast is analysed for the period using historic records of gauge stations along the German and Polish coasts. A compilation of all negative surges recorded at selected water gauges is presented, complete with a statistical analysis of the parameters contributing to their occurrence. The second part contains detailed descriptions of the twenty most dangerous negative surges recorded in the above period, in each case outlining the meteorological situation and describing the impact of atmospheric conditions on coastal sea levels Brief review of scientific contributions Of all publications dealing with sea level changes in the Baltic Sea, that of E. Lisitzin [1974] is the most important one. Several papers have been published to date which discuss extreme water level changes in the Baltic Sea [Majewski 1983, 1961, Stanislawczyk 2001, Sztobryn 2005] or analyse the impacts of dangerous weather situations atmospheric circulation disturbances, steep pressure gradient and strong wind force on surface water oscillations at the coast [Stanislawczyk 2002, Wielbinska 1964]. Unlike storm surges, which cause rising water levels on the coast, negative surges causing water levels to fall have been dealt with to a much lesser extent. Few papers have been published on this subject [Majew ski 1985, Stanislawczyk 2001, 2003, Sztobryn 2001, Wroblewski 1970], among them The low sea levels in the Baltic Sea which discusses general characteristics of low sea levels. The most comprehensive study of negative surges along the Polish coast so far is that of Majewski and Dziadziuszko [1985]. The authors investigated negative surges in the period from 1951 to In most of the more recent studies, negative surges have been discussed only in the context of water level fluctuations in general. The most important recent projects are Studies and Modelling of Severe Hydrometeorological Conditions Along the Polish Coast (Project ERB CE PDCP in connection with the SELF project) and Forecast of Extreme Sea Levels by Artificial Neural Network Western Coast of Poland (Project 3T09003/200/98 of the Scientific Committee of Poland). Three main factors account for the occurrence of negative surges on the coast of Poland: wind, the inverse barometric effect, and the filling level of the Baltic Sea. The general atmospheric conditions leading to extreme water levels are known in principle. Negative surges on the coast of the German Democratic Republic in the period from 1900 to 1980, also including those on the Danish coast, were investigated by Schmager (1984). 75 stormtriggered negative surge events occurred during

9 8 Negative Surges in the Southern Baltic Sea the above period, with a lower frequency in the last two decades than in the first decades. Under extreme conditions, water levels may drop more than 1.5 m in 12 hours. Water levels are correlated with local wind patterns, and the best wind correlation for the GDR coast was found at Arkona. Based on such correlations, it has been possible to develop different statistical prediction models. A very simple model is wind surge curves, with water levels shown as a function of wind speeds and directions. For example, with southwesterly winds of 20 m/s at Arkona, a water level 1 m below normal has to be expected at Warnemünde. However, such simple point correlation inadequately reflects the complicated natural processes taking place. Mewes (1987) distinguished among three different cylone paths causing negative surges on the coast of the GDR: firstly, cyclones which form in the western North Atlantic Ocean and track across the North Sea, secondly, cyclones forming roughly south of Iceland and tracking northeast and, thirdly, cyclones forming off Iceland which track along Scandinavia toward the Nordic Seas but whose centre does not cross the Baltic Sea. After the reunification of Germany, Baerens et al. (1995) studied the frequency of negative surges on the German Baltic Sea coast between Flensburg and Warnemünde without including the eastern part of the Baltic between Warnemünde and the national border of Poland. In contrast to the declining number of negative surges on the coast of Mecklenburg-Vorpommern, their frequency in the period from has actually increased on the coast of Schleswig-Holstein. This contrasting development appears to be linked to the direction of the coast, but its exact cause is still unknown. In both areas, negative storm surges are most frequent in the time from November through January. Water level fluctuations on the coast of Poland and in the eastern part of the German coast are thought to be closely linked, but a cross-border analysis of negative surges has not been carried out so far. Therefore, the development of negative surges in the different coastal sections and the exact causes of differences in the occurrence of negative surges in different parts of the coast still are not fully understood Geographic and hydrodynamic background The region dealt with in this monograph is the south coast of the western and central parts of the southern Baltic Sea. The western part of the Baltic is shaped like a bay opening to the east, whose width increases from 25 nm at Wismar to 120 nm at Kołobrzeg (Fig a). The westernmost part of the southern Baltic coast between Wismar on the Mecklenburg Bay and Cape Arkona on the island of Rügen extends roughly in a southwest to northeastward direction. This part of the coast, covered by the gauges at Wismar and Warnemünde, has a highly variable topography with shallow water and a multitude of creeks, shoals, and sandbanks. The central section of the coast extending from the high chalk cliffs of Cape Arkona to Świnoujście and the Odra estuary (gauges at Sassnitz and Świnoujście) is oriented from northwest to southeast and also has intricate topographic features comprising small sandy coastal islets, narrows, and sandbanks. In the adjacent Pomeranian Bay, also the seabed is highly variable, with shallow depths below 10 m prevailing. A particularly wide belt of shoals exists off the island of Uznam (Usedom), in the waters close to the Świnoujście gauge, and around the island of Wolin. The rather straight eastern part of the coast between Wolin and Kołobrzeg runs in a westsouthwest to east-northeast direction. Also the 10-m-isobath, which is only one nautical mile off the coast, runs in a rather straight line. Considering the subdivision of the coast into three parts differing in their topography, the probability of extreme water levels occurring at Sassnitz would be expected to be on the same order as at Świnoujście. The same holds for the gauges at Wismar and Warnemünde. However, because of the bay effect, the probability of occurrence of extreme sea level events decreases from west to east, as is clearly shown in chapter 3.3. One of the main causes of this phenomenon is the size of the area of open water relative to the coast length and the widening of the bay. The main factor influencing coastal sea levels in the Baltic Sea region is wind, which either pushes the water away from the coast or towards it, whereas tides are of minor importance. Another factor of lesser importance is the chang-

10 Introduction 9 SWEDEN Open Baltic Sea DENMARK Bay effect Sassnitz Warnemünde Kołobrzeg Wismar GERMANY Świnoujście POLAND Fig a The geography of the western and southern regions of the Baltic Sea is shaped like a bay whose width changes from 25 nm at Wismar through 45 nm at Warnemünde, 60 nm at Sassnitz, and 90 nm at Świnoujście to 120 nm at Kołobrzeg. ing water volume in the Baltic Sea. Both the magnitude and characteristics of sea level fluctuations in the Baltic Sea depend, inter alia, on the particular coastline configuration, the exposure of different coastal stretches to the wind, the bathymetry of the adjacent sea basin, and on current patterns in the area. The most spectacular deformation of the water surface off the Baltic Sea shores is caused by stormy, hurricane-like winds. This occurs mostly when a strong low-pressure system tracks along or across the coast, as shown in the example in Fig b. In the morning of 4 December 1999, sea levels along the coasts of the Gulf of Gdańsk (gauges Gdynia and Hel) were rising due to a storm following the passage of a cold front. At the same time, coastal water levels between Wismar and Świnoujście were falling as another perturbance approached. At about 05 UTC on this day, the difference of sea levels on this coast between Hel and Wismar exceeded 260 cm. The range between the extreme values, 600 cm in Hel on 02 UTC and 315 cm in Wismar on 05 UTC, approached 3 m (Fig c). Extremely low water levels are usually more extreme in Wismar than in Kołobrzeg, not only in this example. The explanation is found in the shape of the coast. As has been pointed out above, this part of the Baltic Sea is shaped like a bay. Therefore, a particular water volume removed from or added to the area affects a smaller area in the western part of the bay than in its eastern part. Consequently, because of this so-called bay effect, low water levels in the western part will be lower, and high water levels higher, than in the eastern part of the bay.

11 10 Negative Surges in the Southern Baltic Sea Fig b Variation of sea level at the southern coasts of the Baltic Sea on 3 and 4 December 1999 Fig c Slope of water surface along the coast between Wismar and Hel, 06 UTC on 4 December 1999 (distances between particular water gauges are not presented proportionally)

12 Data and definition Data and definition 2.1. Data This monograph was prepared using hydrological and meteorological data archived at the BSH and IMGW, and available published data. Mareographic records were obtained from the water gauges at Wismar, Warnemünde, Sassnitz, Świnoujście, and Kołobrzeg. All time series start around 1955 and have been analysed up to and including For most of the period reviewed, the German data are available at 1-hour intervals. All Polish data recorded during periods with extreme sea levels (negative and positive storm surges) have been digitised to hourly values. The majority of all other data has been digitised to 4-hourly values. The zero level of tide gauges in Schleswig-Holstein and in Poland is PN = NN-500 cm. In Mecklenburg-Vorpommern, the zero level is PN = HN-514 cm, but the reference level used until October 1985 was NN. Therefore, the gauge station data recorded prior to October 1985 were corrected to match the currently used definition (Die Küste: Die Wasserstände an der Küste Mecklenburg-Vorpommerns von Hans-Joachim Stigge). At the Wismar station, there are large data gaps in The data from July to September are missing because the station was out of service due to maintenance work; these data have been interpolated using data from the nearby gauge at Timmendorf. The correlation coefficient between Timmendorf and Wismar, using the same time span as in linear regression, i. e. 30 days before and 30 days after the data gap, is The standard deviation of the differences between measured and regressed data is 3.8 cm, and the range is 15.0 cm to cm. Also the hourly data for January and February 1963 at Wismar and Timmendorf are missing because the recording devices did not work due to icing. Therefore, only single daily values (7:00 CET) and the lowest and highest values of each month are available. The lowest value in January was 410 cm, and in February 450 cm. The available values were linearly interpolated to hourly values. were calculated using the data of one complete year preceding the missing month in each case. The interpolated curve was corrected using a linear drift, so that there were no jumps between interpolated and measured values. At Kołobrzeg, there are several days for which only a single daily value is available. A total of 805 measurements, corresponding to about 268 days, are missing from the 4-hourly time series. The missing values were interpolated by linear interpolation. As the data available all came from stations located more to the west, the method did not work satisfactorily for Świnoujście. Extreme values from the digital gauge data may deviate slightly from published extreme values because the digital data have a discrete sampling interval (1 h or 4 h), and extreme values from continuous observations may have occurred between these intervals. There also is a difference between hourly and 4-hourly data. The difference was determined by subsampling of the hourly data at Warnemünde. The resulting 4-hourly values were interpolated back linearly to hourly values. The effect of the reducing operations on the annual mean sea level is very small (less than 0.1 cm maximum deviation). The 4-hourly data obtained by subsampling showed equal or higher annual minimum sea levels, with a maximum difference of 9 cm. The mean difference of all annual values was 1.9 cm with an standard deviation of 2.4 cm. The difference in the number of hours per year in which water levels were below 440 cm ranged from 13 to +9 hours, with a mean difference of 0.5 ± 4.3 hours using the 4-hourly data (see Fig. 2.1.). With the linearly interpolated data, values ranged from 0 to +18 hours, the mean difference being 6.3 ± 4.4 hours. There are two gaps in the time series at Świnoujście, with three months data completely missing: November 1978, and August/September These values were interpolated with the values from Kołobrzeg and Sassnitz using a linear function. The parameters of this function

13 12 Negative Surges in the Southern Baltic Sea number of years Difference hourly 4 hourly data in hours Fig Difference between hourly data and resampled 4-hourly data at Warnemünde 2.2. Definition and general characteristics of negative surges According to the definition of the German Institute for Standardization (DIN ), a negative surge is a state of the surface water in which the water level or flow level has fallen to or below a certain value. Depending on the approach used, different limits may be defined. With respect to the German coast, negative surges have been defined as water levels that fall at least 1 m below the generalised mean sea level. In terms of tide gauge data, this means to 400 cm or less. The official German alarm and warning levels are: 425 cm, or 75 cm below mean sea level: surge information is issued 400 cm, or 100 cm below mean sea level: surge warning is issued Navigational warnings (NAVTEX) are additionally issued at water levels below 440 cm, in line with international agreements. values for negative surge warnings differ for particular users, e. g. shipping, hydraulic engineering, port activities, cargo services, or coastguard. For practical purposes, both in the daily hydrological forecasting routine and in scientific studies, a negative surge has been defined as a hydrological situation causing the water level to fall to 440 cm or lower. This value is based on IMGW s thorough analysis of the probability of occurrence of surges in the central part of the southern Baltic Sea coast. The value of 440 cm has been used for the purposes of this monograph. Table 2.2. a shows all negative surge events between 1958 and 2005 during which at least 4 of the 5 gauges included in the study (Wismar, Warnemünde, Sassnitz, Świnoujście and Kołobrzeg) recorded values below 440 cm. The total number of such cases is 107, and in 46 cases all of the 5 gauges fell below the limit. The longest duration of a single negative surge event was 69 hours in December In Poland, negative surge levels have not been officially defined. Depending on the type of activity threatened by negative surges, the threshold

14 Data and definition 13 Table 2.2. a Negative surges in the western and central parts of the southern Baltic Sea coast in (data from 1 h/4 h time series, where at least 4 stations record levels below 440 cm) Beginning, end and duration of negative surge Minimum value of negative surge [cm] No. Beginning End Duration [h] Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg

15 14 Negative Surges in the Southern Baltic Sea Table 2.2. a Negative surges in the western and central parts of the southern Baltic Sea coast in (data from 1 h/4 h time series, where at least 4 stations record levels below 440 cm) (continued) Beginning, end and duration of negative surge Minimum value of negative surge [cm] No. Beginning End Duration [h] Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg

16 Data and definition 15 Table 2.2. a Negative surges in the western and central parts of the southern Baltic Sea coast in (data from 1 h/4 h time series, where at least 4 stations record levels below 440 cm) (continued) Beginning, end and duration of negative surge Minimum value of negative surge [cm] No. Beginning End Duration [h] Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg The lowest sea levels recorded in the period from 1951 to 2005 and since the beginning of observations are given in Table 2.2. b. The lowest negative surge level ever observed was almost 2 m below mean sea level at Wismar; the recorded minima decrease from west to east. Table 2.2. b Lowest sea levels recorded in the western and central parts of the southern Baltic Sea coast Gauge station Lowest sea level in Lowest sea level since the beginning of observations cm Date cm Date Kołobrzeg Świnoujście Sassnitz Warnemünde Wismar

17 16 Negative Surges in the Southern Baltic Sea 3. Seasonal and long term variation Seasonal and annual frequency distributions and long-term variations in the occurrence of negative surges provide important information about this hydrological phenomenon Interannual variation Fig a shows the measured minimum sea level in each calendar year, annual mean and median sea levels, and the values below which sea levels fell for 24, 72, and 240 consecutive hours, respectively. In general, sea level values during negative surges increase from west to east, with the exception of Sassnitz. The difference at Sassnitz as compared to the other gauges, which are located on a straight coast or in a bay, is its geographic location on a land spit. The mean sea level at all gauges has risen over time at a rate of about cm per century (see Table 3.1. a), again with the exception of Sassnitz where the rate is only about 6 7 cm per century. This change observed at the tide gauges has several causes, the most important being global sea level rise and local land rise or subsidence. On a larger scale, the land rises in the north due to post-glacial rebound following melting of the ice shield, and subsides in the south. This difference in land rise may be an explanation for the lower sea level rise at Sassnitz as compared to the other gauges. Observed year-to-year variations of mean sea level are attributable mainly to longer-term wind conditions, which influence water exchange with the North Sea, and to fluctuations of precipitation and riverine runoff. With mean sea level rising, it would appear logical to expect low sea level values to rise as well. The 240-hour values have in fact increased over time, the correlation coefficient with mean sea level changing from 0.57 in the west to 0.85 in the east. However, in the west, the correlation coefficient drops to low levels for the 72-hour (0.28) and 24-hour (0.03) values, and the annual minimum low sea level even shows a decrease for all stat ions except Kołobrzeg. This clearly shows that the direct causes of low sea levels are not the same as those leading to the observed changes of mean sea level. Extremely low sea levels are caused by single, strong wind events, and a better correlation of values with the annual mean (calculated from 365*24 values) is only obtained by combining several values into an integral number (e. g. 72 hourly values to calculate the 72-hour value). Negative correlation may also find an easy explanation: westerly winds continuing for an extended period of time push North Sea water into the Baltic Sea, thus increasing annual mean sea level. But this also increases the possibility of strong south/southwesterly winds causing low sea levels in the western and southern Baltic to drop to extreme values. Table 3.1. a Statistical indicators for mean and low sea level: coefficient of linear regression and correlation with time series of annual MSL values Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg A B C A B C A B C A B C A B C MSL (in cm) , , , , ,1 Level which is 240 h ,9 0, ,20 0, ,0 0, ,9 0, ,5 0,85 undercut for more than the given 72 h 436 6,8 0, ,60 0, ,6 0, ,6 0, ,2 0,75 hours in one year 24 h 415 6,4 0, ,40 0, ,9 0, ,3 0, ,7 0,60 Minimum sea level ,7 0, ,12 0, ,3 0, ,3 0, ,2 0,41 A Constant (for year 2000) from linear regression B Trend (in 2000 year) for linear regression C Coefficient of correlation with annual MSL

18 Seasonal and long term variation Wismar 520 Warnemünde sea level in cm sea level in cm Minimum 388±24 24h Min 417±12 72h Min 434± h Min 453±6 Mean 500±4 Median 500± year Minimum 401±21 24h Min 428±12 72h Min 444± h Min 460±5 Mean 501±4 Median 501± year Sassnitz 520 Świnoujście sea level in cm sea level in cm Minimum 417±17 24h Min 441±9 72h Min 455± h Min 468±6 Mean 504±4 Median 503± year Minimum 419±16 24h Min 437±11 72h Min 449± h Min 463±7 Mean 499±5 Median 498± year Kołobrzeg sea level in cm Minimum 431±16 24h Min 445±12 72h Min 456±8 240h Min 466±8 Mean 501±5 Median 500± year Fig a Minimum sea level, annual mean and median sea level; values below which sea levels fell for 24, 72 and 240 consecutive hours at the Wismar, Warnemünde, Sassnitz, Świnoujśie and Kołobrzeg gauges.

19 18 Negative Surges in the Southern Baltic Sea Annual mean sea levels at the different gauges are quite well correlated, with a minimum correlation coefficient of 0.83 between Wismar and Sassnitz, and a maximum value of 0.98 between Świnoujście and Kołobrzeg (see Table 3.1. b and 3.1. c). By contrast, correlations between the annual minimum values at the stations are relatively low, dropping to 0.25 between Wismar and Kołobrzeg. This low similarity is also apparent in Fig b, which shows the annual minima at all gauges in one Figure. Although there are several years with low values at all stations, some years (e. g. 1972) show high annual minima at Wismar but rather low minima at Kołobrzeg. The correlation coefficients of the 240-hour, 72-hour and 24-hour minima range between those of annual mean sea levels and annual minimum sea levels. In general, the correlation coefficient decreases with increasing geographical distance. Wismar and Warnemünde are the two stations which correlate best, followed by the station pair of Sassnitz Świnoujście Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg 460 sea level in cm year Fig b Annual minimum sea levels at the Wismar, Warnemünde, Sassnitz, Świnoujście and Kołobrzeg gauge stations Table 3.1. b Correlation coefficient between stations: lower left, annual mean sea levels; upper right, annual 240 h low water levels. Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg Wismar X Warnemünde.95 X Sassnitz X Świnoujście X.90 Kołobrzeg X Table 3.1. c Correlation coefficient between stations: lower left, annual minimum sea levels; upper right, annual 72 h low water levels. Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg Wismar X Warnemünde.87 X Sassnitz X Świnoujście X.86 Kołobrzeg X

20 Seasonal and long term variation 19 In conclusion, there is no clear temporal trend in the recorded low sea level values, and low sea level values are independent of annual mean sea levels. There are years in which very low sea levels were recorded which lasted only for a short time, and other years in which the annual minimum was not particularly low but remained at that level much longer. Clear differences have been found in the distribution of low water levels along the coast: there is not only a linear trend with lower minimum values in the west than in the east, but there are also differences in the time series. Fig c shows the annual number of hours during which water levels were below 440 cm. As this is only a different representation of the data shown in Fig a, the above results apply Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg hours <440cm year Fig c Long term variation of low sea level events 440 cm at the Wismar, Warnemünde, Sassnitz, Świnoujście and Kołobrzeg gauge stations 3.2. Seasonal distribution In the mean annual cycle, there is a pronounced difference among monthly distributions, as can be seen in the mean monthly sea level distribution at Warnemünde in Fig a or in the January and June distributions for all five stations in Fig b and c. The monthly mean and median values vary by cm, the maximum is reached in the summer months, and the minimum is reached in winter or spring. An even more important difference regarding extreme sea levels is found in the width of the monthly distributions. In summer, e. g. June, the distribution is quite narrow, with a standard deviation around 12 cm, and shows a pronou nced maximum, with about 34 % of all values spread ±5 cm about the mean. The lowest June value on record is 436 cm at Wismar. The winter distribution, e. g. January, is much wider, with a standard deviation around 28 cm and a less pronounced maximum, with only 16 % of all values spread ±5 cm about the mean. The lowest value ever recorded, 335 cm in Wismar, is much lower than the June value, and this holds for all five stations. A clearer picture of the annual cycle of low sea levels is given in Fig d, which shows the seasonal distribution of sea levels below 440 cm for all five stations. The majority of negative surge events occurred in December and January. This is the stormiest season, with frequent strong southwesterly winds ( ) in the southern Baltic Sea pushing water away from the shore. This explains the high occurrence of water levels below 440 cm during the months from October to February. The largest total number of negative surge events was recorded at the Wismar water gauge, the only station at which such events have been recorded in all the months of the year. In Warnemünde, June was the only month in which water levels below 440 cm were never recorded; Sassnitz, Świnoujście and Kołobrzeg

21 20 Negative Surges in the Southern Baltic Sea did not record any negative surges in May, June, July and August. These are the months in which strong winds or low-pressure systems with galeforce winds occur only rarely. The different westto-east distribution is attributable both to the bay effect and to other local conditions Monthly distribution in % November September 0.00 July May > Water level in cm < March January Fig a Monthly distribution of sea levels at the Warnemünde gauge station Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg Percentage Water level [cm] Fig b Mean sea level distribution at all stations for the month of June. The Y-axis has a logarithmic scale to better depict the tail of the distribution, horizontal lines are drawn in 5% steps.

22 Seasonal and long term variation Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg Percentage Water level [cm] Fig c as in 3.2. b, just for the month of January Wismar Warnemünde Sassnitz Świnoujście Kołobrzeg hours below 440cm VII VIII IX X XI XII I II III IV V VI month Fig d Seasonal distribution of sea levels 440 cm at the Wismar, Warnemünde, Sassnitz, Świnoujście and Kołobrzeg gauge stations

23 22 Negative Surges in the Southern Baltic Sea 3.3. Long-term statistics The Gumbel method is well suitable for evaluating the probability of low sea levels in the Baltic Sea. In Gumbel distributions, extreme-value events are distributed asymmetrically (Fig a). The Gumbel probability curve, which has a positively skewed shape (skewed to the left), describes a double exponential distribution. The number of years used as a basis in computing the Gumbel probability for low water events is T 5 years. The following probability of non-exceedance W (x) can be used as design basis for the occurrence of a low sea water event with the maximum value x: W(x) = e -e-y y = a (x-b) x = cy+a Hence it follows: W(x) = e -e-a(x-b) Probabilities according to the Gumbel method are computed by means of the above conditional equations y = a (x-b) and x = ay+b using annual extreme water levels. They are updated annually. The recurrence intervals T (x) are defined as reciprocal annual probabilities of occurrence: T (x) = 1 1-W(x) Fig a Gumbel distributions Table 3.3. Gumbel probability of low sea levels in m below mean sea level (MSL = 5 m) computed in 2007/2008 for recurrence intervals T (years) Gauge/T in years Flensburg Schleimünde Eckernförde Kiel Neustadt Travemünde Wismar Warnemünde Stralsund Sassnitz Greifswald Świnoujście Kołobrzeg

24 Seasonal and long term variation 23 Table 3.3. and Fig b show Gumbel probabilities for the recurrence interval T (years) at German and Polish gauges. The values in italics have been extrapolated for the Gumbel statistics because at some of the gauge stations, e. g. Świnoujście, the time series covers only a 50- year period. The other values are based on observations covering at least 100 years. From these the interval at which a particular water level is likely to occur on average can be derived. In Warnemünde, for example, a low water level of 1.47 m occurs every 20 years on average. One clearly sees that the probability of occurrence of low sea level events decreases from west to east. One of the reasons for this is the bay effect described in chapter 1.3. The lowest levels occur in bights that are open to the northeast. The values at the gauges of Świnoujście and Sassnitz are in the same range, which is due to their very close geographical position and bathymetry. This can also be seen in the percentile distribution of monthly lowest sea level at the 5 gauge stations (Fig c). A percentile is the value of a variable below which a certain percent of observations fall, i. e. the 20 th percentile is the value (or score) below which 20 percent of all observations fall. The 20 th percentile in Wismar, for example, is 365 cm, in Warnemünde 389 cm, in Sassnitz 406 cm, in Świnoujście 406 cm, and in Kołobrzeg 412 cm. This means that 20 percent of all observations (in this case the monthly low sea level observations) are lower than these values. At Warnemünde 75 % of all values are below 414 cm (or 86 cm below mean sea level), 50 % of all values are below 403 cm (or 97 cm below mean sea level) and 25 % of all values are below 392 cm (or 108 cm below mean sea level). A very long time series of annual low water events has been recorded at the Warnemünde gauge station. Fig d shows annual low sea level occurrences from 1910 to 2005 at the Warnemünde gauge. No data are available for the years 1941/42 and 1945/46. The orange coloured line indicates the water level of 440 cm (60 cm below mean), which is the definition of low water in this monograph. The red line marks the German alert level (400 cm). The 3 blue lines show percentiles from Fig c. The blue solid line represents 75 % of all values, the dashed blue line represents 50 % and the dotted blue line 25 % of all values. Levels below 440 cm have been recorded in all years. Levels which are more than 100 cm below mean water level have not been recorded every year. Extreme values of 140 cm below mean or less are very rare and occurred only twice: in the years 1967 and Low sea level in m Recurrence T in years Wismar Warnemünde Sassnitz winouj cie Ko obrzeg Fig b Low sea level in m as a function of statistical recurrence

25 24 Negative Surges in the Southern Baltic Sea Low sea level Percentile Water level in cm Wismar Warnemünde Sassnitz winouj cie Ko obrzeg Fig c Percentile distribution of monthly lowest sea levels at the 5 gauge stations Low sea levels at the gauge Warnemünde th percentile -108 cm 50 th percentile - 97 cm 75 th percentile - 86 cm navigational level - 60 cm alarm level -100 cm Water level difference from MSL Fig d Minimum values of annual negative surges between 1910 and 2005 Years

26 Meteorological factors contributing to negative surges Meteorological factors contributing to negative surges The dominant factor forcing water surface oscillations in the Baltic Sea is strong wind. As a rule, offshore wind leading to falling coastal water levels is less severe over land than over the sea and may be more or less deflected directionally, depending on the shape of the coastline. However, by choosing a suitable coastal location for the wind measuring station, deflections of recorded wind directions can be kept to a minimum. Strong offshore winds recorded by the coastal stations are normally associated with offshore storms accompanying fast-moving low pressure systems tracking across the Baltic Sea, which affect large sea areas. A relatively rare cause of low water levels, nevertheless worth mentioning, is longlasting gale-force winds connected with an anticyclone over Scandinavia and Eastern and Central Europe. In a high-pressure system of this type, the prevailing E-SE and S winds influence large parts of the Baltic basin. All of these different wind systems, though transformed and very much influenced on their track, develop in accordance with the prevailing pressure pattern over Europe and the adjacent Atlantic Ocean Strong offshore wind on the coast Strong offshore wind is far less severe on the coast than over the sea. Coastal wind measurements made during negative surges have confirmed that, in the large majority of cases (about 90 %), the accompanying wind on the southern Baltic Sea coast came from offshore directions, i. e. ESE-WSW. Alongshore and random directions during periods of low water usually occurred immediately after the wind had veered, when water levels, though rising, had not yet reached the threshold value. The hydrological situation was studied at selected gauge stations in order to determine the distribution of wind directions. Wind directions were used whenever sea levels at the gauge stations had dropped to 440 cm, and one wind measurement made just before the water level dropped to the threshold value was used as well. Therefore, the number of wind records differs at the individual stations. The predominant wind sectors during negative surge events were SW-S. The frequency of these directions was % in the western and central parts of the Baltic coast (e. g. Warnemünde and Świnoujście), and 62 % in the eastern part (Kołobrzeg). The frequency of westerly wind directions was % in the western and central parts, and just below 6 % in the eastern part of the Baltic Sea. The percentage of southeasterly wind directions at the western coast scarcely reached 10 % but was slightly above 17 % in Kołobrzeg. In addition the share of east-southeasterly winds at Kołobrzeg was about 8 %. In the other parts of the coast, this direction occurred only sporadically during approaching storms. Winds from the large W NW (300 ) and eastern (90 ) sectors were extremely rare. As has been pointed out above, these wind directions were only observed occasionally while water levels still were below the defined threshold value but, after having dropped to the minimum value, had already begun to rise. (Fig. 4.1.a. to 4.1.c) a Kołobrzeg b Świnoujście c Warnemünde Fig Frequency distribution of wind directions at sea levels 440 cm,

27 26 Negative Surges in the Southern Baltic Sea 4.2. Offshore storm surges in the wind field of a moving depression The Norwegian and North Seas, Scandinavia, and the Baltic Sea lie in a region of predominantly westerly winds that is crossed regularly by eastward tracking disturbances, mostly active depressions with frontal systems, whose origin is the Atlantic Ocean. Before a low-pressure system reaches the Baltic Sea area, winds mostly have a strong southerly component, but they normally veer after the front has passed. On the southern North and Baltic Sea coasts, approaching depressions are preceded by offshore winds. Low-pressure systems are a common occurrence in this area. The smaller depressions, often low-pressure troughs with atmospheric fronts which are not too deep and move relatively fast, are accompanied by winds which, though reaching gale force, do not affect the sea surface long enough to have a major impact on coastal water levels. By contrast, well developed low-pressure troughs and their frontal systems moving across the coast are accompanied by gale-force backing winds as the fronts approach, and by veering winds after they have passed. This situation normally causes sea level oscillations. Water levels first fall markedly until a sharp minimum is reached, and rise again as the wind veers. Stormy wind in the rear of such fronts causes water levels to rise, sometimes far above the levels recorded at the beginning of the surge. This situation is represented by the mareographic curves in Figs b, 5.6. b and b. Some depressions tracking east begin to slow down as they enter Scandinavia, still deepening. The pressure gradient becomes very steep and the wind, initially gale-force, increases in severity and finally reaches hurricane force. Offshore wind at the southern Baltic coasts causes water levels to fall until the wind either calms or veers. A typical reaction of Baltic Sea levels to such wind forcing is gradually falling water levels in large parts of the coast, often followed by sharply dropping levels as the storm grows to maximum force and, finally, a long-lasting minimum (flat section in the mareograph curve) which lasts as long as the hurricane continues without changing direction. When the wind finally veers, water levels begin to rise more or less rapidly (often supported by alongshore or onshore winds). The mareographic curves in Figs b, 5.9. b, b, b show events associated with this atmospheric situation High pressure system as low sea level generator Another type of low sea level variation can be observed when a strong, stationary anticyclone covers, or oscillates over, Fennoscandia and the northwestern parts of Russia. In such atmospheric conditions, two main factors contribute to falling water levels: one factor is the very high hydrostatic pressure in the powerful high-pressure system, and the other one is the wind system developing at its southwestern edge. While light to moderate winds with a strong northerly component prevail over the northernmost part of the Baltic Sea, winds farther south veer E-SE and increase in severity, reaching gale force in places. This is usually due to a steepening pressure gradient caused by a series of depressions tracking across the area from western Europe. In the westernmost part of the Baltic Sea, the Sounds, and in the southeastern part of the North Sea, SE-S winds prevail because atmospheric pressure in this area is lower than over Scandinavia. Similar configurations of pressure systems persisting long enough in the area a week, two weeks, or even more-force surface water not only away from the shores but out of the sea basin through the Sounds. In such meteorological situations, all coastal water gauges in the Baltic Sea record low water levels. Extreme negative surge events under the influence of an anticyclone are very rare, however. One extreme event was recorded prior to the period studied in this monograph, in February Initially, a southeasterly, moderate to strong air flow persisted over central Europe and the Baltic Sea for eight days, from 7 to 14 February. Then, for another eight days, from 15 to 22 February, the wind system of an anticyclone over Fennoscandia forced surface water away from the eastern and southern Baltic coasts. Water levels dropped to about 440 cm, or even lower, in the central and western parts of the southern Baltic coast before 23 February. On 23 February, a minimum of 427 cm was recorded in Warnemünde and, one day later, 418 cm in Kołobrzeg. This is one of the rare cases of storm-induced negative surges where water levels in the eastern part of the coast dropped below those in the western part. Besides, there was a striking resemblance of the mareographic curves, which ran nearly parallel for a very long time under the impact of the long period of stormy weather (by contrast, during quickly passing storms, water levels in different parts of the same coast often move in opposite directions, compare Fig b). As the strong offshore wind on the southern coast continued, water levels continued to oscillate between 420 cm and cm for several days (Fig. 4.3.).

28 Meteorological factors contributing to negative surges FEBRUARY water level [cm] Warnemünde Kolobrzeg ł Fig Variation of sea levels in Kołobrzeg and Warnemünde during a long high-pressure spell in February Co-occurrence of atmospheric situations over Europe and negative surges at the southern coast of the Baltic Sea A major fall of water levels along large sections of the Baltic coast can only occur if strong offshore winds push water masses from the shore toward the open sea. Therefore, negative surges usually occur during the most dynamic atmospheric conditions, which are characterised by active, windy weather systems. This includes all anemobaric situations with a strong westerly air flow component over the Baltic Sea and the northeastern parts of central Europe, i. e. zonal circulation types and mixed circulation types. These circulation types are characterised by successive atmospheric disturbances tracking rapidly east, whose wind field generates gale-force winds on all Baltic Sea coasts, both offshore and onshore. The frequency of these atmospheric circulation types is about 55 %. The remaining 45 % is a group of atmospheric types containing meridional and considerable easterly components of air flow. Their weather systems typically are more stationary and usually sustain steadier winds, even when they reach gale force. To specify and calculate the frequency of co-occurrence between negative surges and particular atmospheric situations in the years , the calendar of atmospheric situation types over Europe by P. Hess and H. Brezowski was used. In addition, a comparison was made with the average surface pressure charts by G. Cawley. In this way, it has been possible to identify particular features of the individual atmospheric situation types which generate low sea levels. In the classification by Hess and Brezowski, 30 different atmospheric situation types are distinguished. In 11 of these situation types, the westerly (zonal) component of air flow is predominant or at least present over central Europe. The different types are: Wa, Wz, WS, WW, SWa, SWz, NWa, NWz, HM, BM and TM (Fig a); they account for the above mentioned 55 % of all atmospheric situations over central Europe in the time from 1955 to We divided the meridional situations into two groups, the first group encompasses Na, Nz, HNa, HNz, HB, TrM, TB, TrW, and U and accounts for 27 % of all atmospheric situations. The second group with the remaining 18 % of all atmospheric situations includes NEa, NEz, HFa, HFz, HNFa, HNFz, SEa, SEz, Sa and Sz.

29 28 Negative Surges in the Southern Baltic Sea By far the major part, 83.6 %, of all negative surge events during the period cooccurred with the zonal group % occurred during the West Cyclonic pattern Wz (Fig a), and 14.8 % together with the Central European Ridge, BM. The third most important atmospheric type is NWz with about 10 %, the other zonal and mixed situations showed co-occurrence with low sea levels of 6 % or lower. 50 Frequency of sea level in % Wz - 32,5% BM - 14,8% Wa Wz WS WW SWa SWz NWa NWz HM BM TM Na Nz HNa HNz HB TrM NEa NEz HFa HFz HNFa HNFz SEa SEz Sa Sz TB TrW U West Anticyclonic West Cyclonic Southern West Angleformed West South-West Anticyclonic South-West Cyclonic North-West Anticyclonic North-West Cyclonic Central European High Central European Ridge Central European Low North Anticyclonic North Cyclonic North Iceland High Anticyclonic North Iceland High Cyclonic British Isles High Central European Trough North-East Anticyclonic North-East Cyclonic Fennoscandian High Anticyclonic Fennoscandian High Cyclonic Norwegian Sea - Fennoscandian High Anticyclonic Norwegian Sea - Fennoscandian High Cyclonic South-East Anticyclonic South-East Cyclonic South Anticyclonic South Cyclonic British Isles Low Western European Trough Unclassifiable 5 0 Wa Wz WS WW SWa SWz NWa NWz HM BM TM Na Nz HNa HNz HB TrM NEa NEz HFa HFz HNFa HNFz SEa SEz Sa Sz TB TrW U Atmospheric situation type Fig a Co-occurrence frequency of particular atmospheric situations and negative surge events 440 cm at the southern Baltic Sea coast, (in the inner frame: symbols and specification of atmospheric situations over Europe, according to G. Hess and H. Brezowski) Wz West Cyclonic Fig b Atmospheric situation Wz (West Cyclonic), which causes most of the negative surges on the southern Baltic Sea coast (average surface level pressure anomaly chart, after G. Cawley) 1200

30 Meteorological factors contributing to negative surges 29 SEa South-East Anticyclonic Fig c Atmospheric situation SEa (South-East Anticyclonic) from the group of meridional situations. Weather situations like this have caused long-lasting negative surges 440 cm on the southern Baltic Sea coasts (average surface level pressure anomaly chart, after G. Cawley) The first group of meridional situations usually induce negative surges of short duration, similar to the zonal and mixed types of atmospheric situations discussed above. During the period studied, 11.3 % of negative surge events were attributable to this group of atmospheric situations, with HB being the most important single situation. Among southerly and southeasterly atmospheric situations, which are closely related and account for 4.8 % of all negative surges observed, the southeasterly anticyclonic type (SEa) prevailed (Fig c). It should be noted that no negative surge event of very long duration occurred in the central part of the southern Baltic Sea coast in the 56 years analysed in this monograph. Only 5.1 % of all negative surge events were attributable to the second meridional group. They included events of above-average duration.

31 30 Negative Surges in the Southern Baltic Sea 5. Most severe negative surges on the southern Baltic Sea coast 5.1. November 1956 Meteorological situation On 24 November 1956, while the Baltic Sea still was under the influence of a weak high-pressure ridge, a wide low-pressure trough over the Norwegian Sea travelled southeast, crossing the western part of Scandinavia. The southern Baltic Sea coasts were governed by an initially weak, later moderate westerly air flow which backed SW in the late evening, increasing gradually to 7 Bft. On 25 November, the trough still tracking eastward deepened considerably. The SW-S storm reached 8 10 Bft in the whole Baltic Sea region. As the cold front tracked across the western and central parts of the southern Baltic coasts in the late hours of this day, the 8 9 Bft storm veered W-NW, slowly abating later. Hydrological response of sea level Sea levels remained just under 500 cm until the afternoon of 24 November. In the late hours of 24 November, the trough reached the Baltic Sea and the southern coasts came under the influence of increasing westerly winds, which gradually veered SW and S, causing sea levels to fall until they reached their minimum values in the late hours of 25 November. The minima occurred nearly simultaneously along the entire southern Baltic coast. Minimum values of 342, 365 and 383 cm were recorded in Wismar, Warnemünde and Sassnitz, respectively, at 18 UTC, and in Świnoujście and Kołobrzeg at 20 UTC, with values of 401 and 393 cm, respectively. In the night of 26 November, when the storm front had passed, the stormy winds backed west, later northwest. Sea levels responded immediately and began to rise, reaching values close to or slightly above 500 cm as early as the morning of 26 November. Fig a Pressure pattern and wind field over the Baltic Sea on 25 November 1956 at 12 UTC

32 Most severe negative surges on the southern Baltic Sea coast November water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of November January 1960 Meteorological situation On 17 January, as a blocking anticyclone lay over Russia, an active depression over Scotland moved southeast, reaching northern Denmark in the evening of that day. On 18 January, the southern parts of the Baltic Sea came under the influence of gale-force southerly winds of 7 Bft, which decreased temporarily to about 6 Bft in the course of the day, backing slightly in the eastern part of the Baltic. In the night from 18 to 19 January, the depression over Denmark deepened and moved northeast toward southern Sweden. On the southern coast of the Baltic Sea, prevailing southerly and southwesterly offshore winds reached 8 9 Bft in the western part of the coast. On 19 January, the depression continued tracking northeast, filling slowly. In the early morning of that day, atmospheric fronts associated with the depression crossed the southern coasts, with more severe weather observed in the western part of the coast. Shortly past noon, after the cold front had crossed the coast, winds backed west to northwest and decreased to 6 5 Bft and less, becoming light and variable. Hydrological response of sea level Low sea levels along the southern coast of the Baltic Sea lasted for several days. Around midnight of 17/18 January, they oscillated between 425 and 455 cm. An offshore southerly storm over the westernmost part of the coast increased temporarily to 8 9 Bft, causing water levels in the area to fall slightly in the early hours of 18 January: to about 415 cm in Wismar, and about 418 cm in Warnemünde. The next spell of stormy offshore winds on 19 January lowered sea levels along the whole southern coast: in Wismar, the minimum was as low as 379 cm, in Warnemünde 398 cm, in Sassnitz 414 cm. Świnoujście recorded 416 cm, and Kołobrzeg 425 cm. When the wind changed to onshore westerly, later northwesterly directions, sea levels rose to about 500 cm in the late hours of 19 January.

33 32 Negative Surges in the Southern Baltic Sea Fig a Pressure pattern and wind field over the Baltic Sea on 19 January 1960 at 00 UTC 540 January water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of January 1960

34 Most severe negative surges on the southern Baltic Sea coast January 1961 Meteorological situation A large anticyclone was centred over the Ukraine for several days, with ridges extending across the Baltic Sea and to Scandinavia. On 27 January, the high pressure system moved southeast, and westerly airflow became established over the Baltic Sea. Winds backed southwest, then south, and increased to about 6 Bft. Early on 28 January, as a low pressure trough approached the area, the slightly offshore directed wind increased to 7 Bft. In the afternoon of that day, the wind calmed down again to 5 6 Bft, veering slightly to onshore directions as the frontal system travelled east. A low-pressure trough crossed the Baltic Sea in the morning of 29 January. The wind direction backed again south, now blowing in offshore direction, and increased to 7 8 Bft. A low-pressure centre which was tracking from northern Scotland to southern Finland slowly crossed the area on 29 and 30 January, causing a strong southwesterly air stream over the whole southern part of the Baltic Sea on 30 January. Wind force reached 8 9 Bft. Around noon on 30 January, after the cold front had passed, the wind veered to westerly directions and decreased slowly. Hydrological response of sea level Steadily blowing light to moderate offshore winds, high atmospheric pressure over the sea basin, and seasonally diminished runoff led to low sea levels along the entire southern Baltic coast. Towards the last pentad of January, sea levels oscillated around 470 cm. On 28 January, the SW-S storm led to gradually falling sea levels, from 430 to 410 cm recorded at Wismar and Warnemünde. Sea levels at Sassnitz, Świnoujście, and Kołobrzeg oscillated slightly below 440 cm. Around noon on 28 January, the wind veered to westerly directions and sea levels began to rise again, reaching cm. At about 9 UTC on 29 January, after the stormy wind had backed south, sea levels dropped rather rapidly, though not to very low values. The following minima were recorded: 409 cm in Wismar, 407 cm in Warnemünde, 415 cm in Sassnitz, 398 cm in Świnoujście, and 412 cm in Kołobrzeg. Around noon on 30 January, the wind veered to westerly directions, causing sea levels to rise again, with values of about 480 cm reached around noon on 31 January. Both of the recorded minima were flat and shallow. Fig a Route of the depression centre from 29 January 18 UTC to 31 January 1961, and pressure pattern and wind field over the Baltic Sea on 30 January 1961, 00 UTC

35 34 Negative Surges in the Southern Baltic Sea 540 January water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of 27 to 31 January February 1962 Meteorological situation On 11 February, an active depression originating from the area north of Scotland tracked rapidly east, deepening as it crossed the Norwegian Sea and southern Norway. On 12 February around noon, its centre of about 955 hpa was over Stockholm. The pressure gradient was very steep in the entire moving system. The wind system induced by the approaching depression generated gale-force southwesterly storm of 9 10 Bft which backed slowly in the northeastern part of the coast and gradually veered in its southern part. Wind directions on the southern coasts, in some places even behind the cold front, remained nearly parallel to the coastline for several hours. Winds only veered west after the cold occlusion had crossed the coasts shortly after noon on 12 February. The onshore westerly winds reached the northernmost part of the coast first, and the westernmost part last. Hydrological response of sea level Sea levels on the southwestern coast of the Baltic Sea oscillated close to mean sea level. In the night between 11 and 12 February, the southwesterly storm led to a smooth, gradual decrease of sea levels which began around midnight. The passage of the atmospheric frontal system interrupted the gradual sea level decrease, and slightly higher levels were first observed at Sassnitz and Świnoujście, as early as 12 UTC, followed by Kołobrzeg at 13 UTC. Around 17 UTC, the sea level also rose at Warnemünde. Finally Wismar recorded a rising sea level at about 19 UTC. The minimum values recorded this afternoon were as follows: Wismar 384 cm, Warnemünde 394 cm, Sassnitz 414 cm, Świnoujście 428 cm, and Kołobrzeg 452 cm. Sea levels then rose again gradually.

36 Most severe negative surges on the southern Baltic Sea coast 35 Fig a Route of the low pressure centre from 11 February 18 UTC to 12 February 12 UTC 1962, pressure pattern and wind field over the Baltic Sea on 12 February 1962, 12 UTC 540 February water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of February 1962

37 36 Negative Surges in the Southern Baltic Sea 5.5. December 1965 Meteorological situation In the early morning of 5 December, moderate southerly to southwesterly winds prevailed on the southern Baltic Sea coasts. At about 06 UTC, a secondary low pressure centre located at the southwestern edge of a wide depression northeast of Scotland formed over Wales. This secondary low deepened rapidly as it travelled quickly in northeastern direction, crossing southern England, the southern coasts of the North Sea, and Denmark. After having slowed down temporarily, it reached southern Sweden on 6 December at 00 UTC, with 960 hpa measured in its centre. Slowing down further and becoming weaker, the centre arrived at the entrance to the Gulf of Finland at 18 UTC and continued tracking east as it filled. Hydrological response of sea level The decrease of sea levels began shortly before midnight on 6 December and continued until the storm veered to slightly onshore directions. The minimum was first reached at Kołobrzeg, at 438 cm, and one hour later at Świnoujście, which recorded a minimum of 430 cm, followed by Sassnitz where 412 cm was measured at 10 UTC. The curve of the level graph was flat at the western gauges. The lowest value of about 408 cm in Warnemünde was recorded at about 11 UTC. Wismar recorded the minimum value of 386 cm at about 12 UTC. After the storm had veered lightly onshore, sea levels began to rise again until they were close to mean sea level around midnight on 7 December. The wind field generated by this pressure system resulted in a strong southerly wind of 6 8 Bft backing southeast, partly east, which swept across the Baltic Sea on 5 December and the early hours of 6 December. The occluded front reached the water level gauges of the region between 8 and 13 UTC on 6 December (the easternmost gauges first). After the occlusion the wind veered and became gusty, up to 8 10 Bft. Fig a Route of the depression centre from 06 UTC on 5 December to 18 UTC on 6 December, pressure pattern and wind field over the Baltic Sea on 6 December 1965, 00 UTC

38 Most severe negative surges on the southern Baltic Sea coast December water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of 5 to 6 December October 1967 Meteorological situation A depression approaching from the Atlantic Ocean reached the southwestern coast of Ireland on 16 October at 18 UTC. On 17 October, the deepening low moved rapidly across the British Isles and the North Sea toward Denmark and southern Sweden, where it slowed down considerably and reached the lowest value of 967 hpa in its centre. Before midnight on 17 October, a rapid intrusion of frosty Arctic air caused the centre to move fast in the direction of the White Sea, where it arrived on 18 October around noon (Fig a). In the afternoon and night of 17 October, when the centre was almost stationary over the Kattegat and southern Sweden, a very strong westerly to southwesterly storm of 8 9 Bft, and of 10 Bft in places, developed over the eastern North Sea and the southwestern basins of the Baltic Sea. Behind the occluded front, the storm veered northwest in the early hours of 18 October, without calming during the next several hours. Hydrological response of sea level On 17 October, sea levels on the southwestern Baltic Sea coast oscillated slightly above the mean value. Around noon, water levels dropped first in the Wismar Bay, which is the area most sensitive to the impact of gale-force offshore winds. Water levels began to fall steadily at a rate of initially about 10 cm/hour, later cm/hour. A less regular rate of decrease was recorded at the other water level gauges. Kołobrzeg was the last station to record falling water levels on this part of the coast, with values remaining above 500 cm until the warm sector had passed east, and westerly (alongshore) winds had backed SW, partly S, at about 21 UTC. This forced a rapid drop of sea levels in this area. Minimum levels were recorded just after midnight on 18 October. Between 01 and 04 UTC, as the occlusion was moving east, the hurricane-like storm veered rapidly NW. On the occluded front, however, the storm still came from southerly directions, causing water levels to drop at particularly rapid rates: rates of decrease were as high as about 40 cm/h in Sassnitz, and about 50 cm/h in Kołobrzeg and Świnoujście. The lowest minima were as follows: Warnemünde 332 cm, Wismar 334 cm, Świnoujście 366 cm, Sassnitz 380 cm, and Kołobrzeg 410 cm. The severity of the storm, now coming from NW-N, caused sea levels to start rising again immediately at high rates and, at the eastern gauges, to compensate the difference of more than 1.5 m in 5 7 hours.

39 38 Negative Surges in the Southern Baltic Sea Fig a Route of the depression from 16 October 18 UTC to 18 October 18 UTC, pressure pattern and wind field over the Baltic Sea on 17 October 1967, 18 UTC 540 October water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of October 1967

40 Most severe negative surges on the southern Baltic Sea coast March 1969 Meteorological situation In the early hours of 8 March, a weak ridge of high pressure moved east across the Baltic Sea, with moderate westerly to southwesterly winds blowing on the southern coasts. In the afternoon, an active low pressure centre with an associated frontal system moved from the Norwegian Sea toward southern Sweden, where it arrived early on 9 March. Here, it slowed down slightly and changed direction toward the Baltic Sea Proper, continuing in easterly direction. In the afternoon of 8 March, the wind increased gradually and reached 7 9 Bft on the southern coasts. Shortly after midnight on 9 March, the squall line of a cold occlusion passed across the two easternmost water level gauges, while the western gauges remained in the area of the less gusty southwesterly storm, which was increasing in severity. Around noon on 9 March, a secondary cold front moved first across the water level gauges in the eastern part of the southern Baltic coast, then those in the western part. The storm, which now reached 9 10 Bft and 11 Bft in gusts, veered west and northwest, slowly decreasing in the evening. Hydrological response of sea level In the morning of 8 March, sea levels oscillated between 480 cm and 460 cm, falling gradually under the influence of freshening offshore wind. Levels had dropped to cm by night, and shortly after midnight on 9 March all gauges except the Kołobrzeg station recorded levels just under 420 cm. At the same time, shallow minima of 430 cm and 412 cm were recorded at Kołobrzeg and Świnoujście, respectively. Levels at the western gauges continued to sink slowly, and the minima were reached around noon: 408 cm in Sassnitz at about 11 UTC, 392 cm in Wismar at 12 UTC, and 398 cm in Warnemünde at 13 UTC. Around this time, the disturbed water level curves at Kołobrzeg and Świnoujście showed secondary minima. Levels rose again under the impact of the northwesterly storm and reached cm in the late hours of 9 March. Fig a Pressure pattern and wind field over the Baltic Sea on 9 March 1969, 00 UTC

41 40 Negative Surges in the Southern Baltic Sea 540 March water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of 8 9 March January 1979 Meteorological situation Early on 6 January, a cyclonic centre formed southwest of the Faroe Islands on a cold front in the rear of a low pressure trough. This young centre moved rapidly northeast and reached the northern part of the Norwegian Sea at about 12 UTC on 7 January, while the trough moved eastward. The occluded front lay over Scandinavia as the warm front had reached the entrance to the southern basins of the Baltic Sea. Winds preceding the warm front in the eastern part of the trough increased over the whole Baltic Sea and developed into a southwesterly storm of 7 9 Bft as the whole depression deepened. Along the southern coasts, however, the passage of the warm front was accompanied by backing winds and a temporary decrease of wind speed. Towards evening, the passage of the cold front again brought an increase in wind speed, and after about 20 UTC the storm veered west, then west-northwest, in an onshore direction. Hydrological response of sea level In the early hours of 6 January, water levels began to sink slowly at first, accelerating in the early hours of 7 January under the impact of the strengthening southwesterly storm. When winds decreased between 9 and 13 UTC and backed somewhat (Fig a) in the warm frontal zone, also the rate of sea level decrease slowed down, but it increased again before the passage of the cold front. Between 20 and 23 UTC, the offshore winds veered in the rear of the cold front, and levels began to rise slowly. Values of about 480 cm were reached as late as about 20 UTC on 8 January. The recorded minima were 372 cm in Wismar and Warnemünde at about 18 UTC on 7 January; 394 cm in Sassnitz at 22 UTC, 410 cm in Świnoujście, and 403 cm in Kołobrzeg, both at about 17 UTC on 7 January.

42 Most severe negative surges on the southern Baltic Sea coast 41 Fig a Route of the depression from 6 January 12 UTC to 7 January 12 UTC, pressure pattern and wind field over the Baltic Sea on 7 January 1979, 12 UTC 540 January water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of 6 8 January 1979

43 42 Negative Surges in the Southern Baltic Sea 5.9. November 1979 Meteorological situation On 2 and 3 November, Scandinavia and the Baltic Sea area lay between an anticyclone from Finland tracking southeast and a low pressure system advancing slowly from the Norwegian Sea. The pressure gradient over the area steepened, and around noon on 3 November the whole Baltic Sea region was under the influence of an intensive southerly to southeasterly air flow that preceded the low pressure trough with its associated frontal system. The trough deepened as it entered Scandinavia and the Baltic Sea in the afternoon of 3 November. By night, galeforce winds from southwesterly directions had reached 7 9 Bft. The SW storm continued until the late hours of 4 November, when it veered west and decreased temporarily in the western part of the coast after the cold front had tracked across the southern coast. Hydrological response of sea level Water levels had been slightly below the mean values since 2 November. On 3 November around noon, the strong offshore wind caused a gradual fall of water levels. This time, deeper minima were recorded at the eastern water level gauges than at the western ones. The lowest values were recorded at more or less the same time in the late afternoon of 4 November, between 18 and 19 UTC. 372 cm was measured at Wismar, 381 cm at Warnemünde, 387 cm at Sassnitz, 370 cm at Świnoujście, and 370 cm at Kołobrzeg. Fig a Pressure pattern and wind field over the Baltic Sea on 4 November 1979, 12 UTC

44 Most severe negative surges on the southern Baltic Sea coast November water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of 3 5 November November 1981 Meteorological situation In the second half of November, with westerly air flow prevailing over Europe, a succession of low pressure systems from the Atlantic Ocean moved eastward. One of these disturbances formed over England in the afternoon of 23 November and travelled quickly northeast across the Norwegian Sea and southern Norway, where atmospheric pressure dropped below 965 hpa. On 24 November at 18 UTC, the low pressure centre passed Stockholm, veered southeast and reached the Gulf of Finland at about 06 UTC on 25 November, filling gradually. The pressure gradient of this depression was very steep. Intensive air flow over the southern areas of the Baltic Sea gradually changed from southeasterly directions in the eastern basins to southwesterly flow in the western basins and developed into a storm as early as the night of 23 November. Early on 24 November, as the pressure gradient continued to steepen over the Baltic Sea, the storm reached 9 10 Bft and locally exceeded 10 Bft. Around midnight, the storm veered west, then northwest, first in the eastern part of the area (about 20 UTC on 24 November) and then, early on 25 November (between 3 6 UTC on 25 November) in the west. The strong onshore winds over the southern Baltic Sea began to calm as the low in the southeastern part of the Gulf of Finland filled gradually. Hydrological response of sea level On 23 November, water levels were above the mean values. However, as early as 24 November, levels began to fall rapidly, with higher rates recorded in the western sections of the coast under the impact of the intensifying storm, which was growing in strength and backing to offshore directions. During these hours, the eastern part of the coast was under the influence of a shallower pressure gradient with temporarily calmer winds, which was reflected in the behaviour of sea levels in the area (e. g. Kołobrzeg). In the western part of the coast, water levels continued to fall at irregular rates from 24 November until the early hours of 25 November (00 04 UTC). Next, when the storm veered onshore, levels began to rise again rapidly. The lowest values during this storm surge were as follows: Kołobrzeg 450 cm at 21 UTC on 24 November; Świnoujście 409 cm at 16 UTC on 24 November; Sassnitz 403 cm at 23 UTC on 24 November; Warnemünde 368 cm between 03 and 05 UTC on 25 November; Wismar 331 cm at 03 UTC on 25 November.

45 44 Negative Surges in the Southern Baltic Sea Fig a Route of the low pressure centre from 23 November 12 UTC to 25 November 1981, 06 UTC, pressure pattern and wind field over the Baltic Sea on 24 November 1981, 00 UTC 540 November water level [cm] Wismar Warnemünde Sassnitz winouj cie Kołobrzeg MSL Fig b Variations of sea level decrease during the storm of November 1981

46 Most severe negative surges on the southern Baltic Sea coast November 1985 Meteorological situation On 5 November, southeasterly to southerly air flow prevailed over southern Scandinavia and the Baltic Sea along the southwestern edge of an anticyclone approaching from the Ukraine. The anticyclone slowly retreated northeastward in front of a low pressure trough associated with a depression over Scotland, which started travelling east at 00 UTC on 5 November, deepening. As the anticyclone retreated very slowly, the pressure gradient in the advancing trough steepened, particularly in the westernmost part of the Baltic Sea. In consequence, the strong southeasterly to southerly winds in the area increased in severity, especially when the occluded front crossed the Baltic Sea in the morning of 6 November, while the depression centre, which was below 960 hpa, remained stationary over the Sounds and continued to deepen. Behind the occlusion, winds of 8 9 Bft, locally 10 Bft, veered southwest and west later and continued blowing in the Baltic Sea region until the depression centre moved to the area of Stockholm late on 6 November, filling slowly. Hydrological response of sea level Sea levels were close to the mean values until the early hours of 6 November. Under the impact of an increasing offshore storm, water levels began to fall, rapidly at first as long as the wind direction was southerly, then at a slower rate as it veered in an alongshore direction. In the night of 6 November, flat minimum levels remained for about 7 9 hours until the wind veered to W-NW directions early on 7 November (about 00 UTC in the western part, and 03 UTC more to the east). Water levels then returned gradually to the mean values. The lowest values were recorded between 20 and 21 UTC on 6 November: Wismar 377 cm, Warnemünde 389 cm, Sassnitz 420 cm, Świnoujście 415 cm, and Kołobrzeg 457 cm around 00 UTC on 7 November. Fig a Route of the depression centre from 5 November 00 UTC to 6 November 18 UTC, pressure pattern and wind field over the Baltic Sea on 6 November 1985, 12 UTC

47 46 Negative Surges in the Southern Baltic Sea 540 November water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of 6 November January 1990 Meteorological situation An active low pressure centre originating in the area southeast of Greenland travelled eastward on 24 January and reached northern Ireland on 25 January. As it continued tracking east, the centre deepened over the North Sea until it reached its lowest pressure of 949 hpa at 18 UTC on 25 January. Around noon on 26 January, the centre was over southern Scandinavia, and early on 27 January it reached southern Finland (Fig a). The depression centre approaching from the British Isles and tracking toward southern Finland was preceded by a field of a very steep pressure gradient. The low was accompanied by initially moderate southwesterly winds which in the rear of the cold front veered temporarily and later reached gale force. In the afternoon of 25 January, as a southwesterly hurricane of Bft developed over the English Channel and the southern coasts of the North Sea, an easterly storm of 9 10 Bft hit the southwestern coasts of Norway. Behind the colt front, in the early hours of 26 January, the hurricane raged across eastern England (NW-W winds of 9 10 Bft), the southern North Sea region and coasts (SW hurricane of 12 Bft), Denmark (SW backing hurricane of Bft), and the western and southern areas of the Baltic Sea (SW hurricane of 9 11 Bft, veering slightly). It was not until the late hours of 26 January that the storm began to abate, although in the morning of 27 January winds on the southern Baltic Sea coasts locally still gusted up to 7 8 Bft. Hydrological response of sea level In the early hours of 26 January, sea levels oscillated above the mean values. Very soon, however, between 03 and 07 UTC, as the frontal system quickly traversed the area, sharp disturbances in the direction of the W-SW hurricane passed along the southwestern coast. Rapid water level decreases of short duration were the first response. Between 03 and 04 UTC, the rates of decrease were as high as 50 cm/h in Wismar and about 35 cm/h in Świnoujście (Fig b). The other gauges recorded this event between readings. The decrease was followed by a short-lasting increase of levels between 04 and 07 UTC due to veering wind behind the cold front. In the next hours, when the hurricane again changed direction from nearly alongshore to offshore, water levels fell to very flat minima between 17 and 22 UTC in the western part of the coast, and between 17 UTC on 26 January and 02 UTC on 27 January further east. The lowest value of 335 cm was recorded on 26 January at 16 UTC in Wismar, where water levels remained below 340 cm for 6 hours. On 26 January, Warnemünde recorded a minimum of 375 cm at 19 UTC, Sassnitz 418 cm at 16 UTC, Świnoujście 415 cm at 19 UTC, and Kołobrzeg 461 cm at 17 UTC.

48 Most severe negative surges on the southern Baltic Sea coast 47 Fig a Route of the depression centre from 25 January 00 UTC to 27 January 00 UTC, pressure pattern and wind field on 26 January 12 UTC, January water level [cm] Wismar Warnemünde Sassnitz winouj cie Kołobrzeg MSL Fig b Variations of sea level decrease during the storm of January 1990

49 48 Negative Surges in the Southern Baltic Sea February 1990 Meteorological situation Europe had been under the influence of westerly and southwesterly air flow for several days, which freshened over the Baltic Sea and temporarily reached gale-force. Early on 26 February, an active depression of 963 hpa appeared west of Scotland. Moving rapidly east, it reached the entrance to the Skagerrak around noon, slowing down: southern Sweden was reached at 18 UTC on that day, and the Alands Islands as late as about 06 UTC on 27 February. There, it nearly stopped, with its deepest pressure of 939 hpa recorded at 09 UTC on 27 February. The depression was exceptionally dynamic despite its rather slow movement. It was preceded by a large field of intensive negative-pressure tendencies, locally over 13 hpa/3 h. An intrusion of cold Arctic air streaming into the southern peripheries of the depression in the rear of the cold front forced an increase of air pressure. The positive tendencies behind the cold front locally exceeded 15 hpa/3 h. In consequence, a very steep pressure gradient formed over an area extending from the English Channel across the southern coast of the North Sea and the total area of Jutland to the Baltic Sea. Hydrological response of sea level On 26 February, the increasing southwesterly storm caused sea levels to oscillate irregularly around the mean values. Sea levels did not begin to fall until late in the evening: more rapidly in the westernmost part, at Wismar, and slower towards the east. As water levels fell, they continued oscillating in line with the changing directions of the gusty offshore to alongshore storm. The decrease was rather uneven at all gauges of the coastal area, so that the lowest values were recorded at different times at the particular stations. The variation curves were flat. In Wismar, for instance, a sequence of very low values was recorded between two minima: the first minimum of 395 cm occurred at 02 UTC, and the second one, 394 cm, at about 08 UTC. 405 cm was never exceeded between these two readings. In Warnemünde, the highest levels recorded for 7 consecutive hours were 414 cm at 03 UTC and 412 cm at 10 UTC, with the minimum of 398 cm recorded at 07 UTC. At Sassnitz, the minimum of 403 cm was recorded at about 04 UTC, Świnoujście 407 cm at 03 UTC, and Kołobrzeg 443 cm at about 05 UTC. Water levels did not begin to rise more steadily until 10 UTC on 27 February and had nearly returned to the mean values by evening. The wind field development followed the pressure pattern. From noon on 26 February, the intensity of the southwesterly wind increased, exceeding 8 9 Bft in the Kattegat and over Denmark. In the afternoon of that day, the heavy storm spread eastwards: in the Danish Sounds and in the southern part of the Baltic Sea, it increased to 11 Bft and became gusty as cold Arctic air flowed into the area. In the morning of 27 February, the storm continued unabated but veered to westerly alongshore and slightly onshore directions, spreading across the entire area of the Baltic Sea from the Kattegat to Palanga, and from Łeba to Gotska Sandön.

50 Most severe negative surges on the southern Baltic Sea coast 49 Fig a Route of the low pressure centre from 26 February 00 UTC to 28 February 00 UTC, pressure pattern and wind field over the Baltic Sea on 27 February 1991, 00 UTC 540 February water level [cm] Wismar Warnemünde Sassnitz winouj cie Kołobrzeg MSL Fig b Variations of sea level decrease during the storm of February 1990

51 50 Negative Surges in the Southern Baltic Sea January 1993 Meteorological situation With an anticyclone over southern Europe, northern Europe was under the influence of low pressure. In the morning of 13 January, an active, newly formed depression from the Atlantic Ocean approached the British Isles from the southwest. The depression and associated fronts moved northeast, deepening fast, and reached the Kattegat by night. Early on 14 January, the depression crossed southern Sweden and the Baltic Sea Proper and, slowing down, entered Estonia at 09 UTC. At 15 UTC on the same day, the depression was centred over St. Petersburg, from where it turned east, filling as it reached the area south of Lake Onega. On 13 January, strong westerly winds backing southwest prevailed over the southern part of the Baltic Sea. Early on 14 January, as the low pressure centre and fronts crossed the Baltic Sea, the gale-force wind developed into a heavy storm which reached hurricane force over the southern Baltic Sea region between 02 and 06 UTC. Before leaving the Baltic Sea area in the morning of 14 January, the low pressure trough forced the storm to veer temporarily west to northwest (Fig a), causing the wind, still strong and gusty, to back and calm down very slowly. Hydrological response of sea level On the days preceding the surge, strong southwesterly winds kept sea levels considerably below the mean values. The gauge at Wismar, for example, recorded levels below 420 cm for about 6 hours on 13 January. In the following night, disturbances of wind direction and speed near the advancing atmospheric fronts first provoked a small decrease (between 00 and 03 UTC), then a rapid but short-lasting rise of water levels (between 02 and 06 UTC). The highest level of about 560 cm was recorded in Kołobrzeg, 530 cm was reached about one hour earlier in Warnemünde, and about 535 cm was recorded at Świnoujście at 05 UTC. This rise of water levels was followed by a much steeper drop: the water level in Świnoujście dropped 130 cm in 4 hours, in Kołobrzeg about 120 cm in 3 hours, and in Wismar 110 cm in 6 hours. The decrease stopped abruptly when the storm veered slightly onshore. The minima at the individual stations were as follows: Kołobrzeg 439 cm at 08 UTC, Świnoujście 400 cm at 09 UTC, Wismar 367 cm at 10 UTC, Sassnitz 386 cm at 14 UTC, and 404 cm in Warnemünde. After having reached their minima, water levels rose again rather quickly though very unevenly due to the impact of highly variable air flow. Fig a Route of the low pressure centre from 09 UTC on 13 January to 00 UTC 15 January 1993, pressure pattern and wind field over the Baltic Sea at 06 UTC on 14 January 1993

52 Most severe negative surges on the southern Baltic Sea coast January water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig b Variations of sea level decrease during the storm of January February 1996 Meteorological situation On 15 February, two depressions travelled towards the Baltic Sea. The first depression, originating in northern Norway, tracked across Finland and reached Estonia early on 16 February, filling as it continued in southeasterly direction. The other depression approached from the area off Iceland and crossed the Norwegian Sea, deepening. Its centre moved across southern Scandinavia and reached the Baltic Sea late on 16 February with a pressure of 974 hpa. Early on 17 February, the low pressure trough with the frontal system passed Gotland, entered Latvia and then backed east, filling. On 15 February, a westerly storm of 9 Bft which soon turned southwest developed in the field of the steep pressure gradient which accompanied the first of the two depressions. In the western part of the coast, the storm locally exceeded 9 Bft. Early on 16 February, after the low pressure trough had entered the Baltic Sea, the storm behind the cold front veered temporarily west to northwest, beginning in the eastern part of the coast and later in its western part. These wind directions were unchanged until around noon in the eastern part, and afternoon in the western parts of the coast. In the afternoon of 16 February, as the other low pressure trough with its associated frontal system was moving across the Baltic Sea, the direction of the gale-force winds oscillated between W (temporarily NW) and SW. Behind the occluded front, which crossed the area toward noon on 17 February, the winds veered northwest to northeast. Hydrological response of sea level Sea levels on the days preceding the surge were low, oscillating around 460 cm. On 15 February, the southwesterly offshore storm caused water levels to drop. The minima, recorded around midnight, were 409 cm at Kołobrzeg, 405 cm at Świnoujście, and 383 cm at Sassnitz, all between 22 and 23 UTC on 15 February. Further west, in Wismar, the minimum level of 363 cm was recorded around 01 UTC, and the minimum of 379 cm in Warnemünde around 02 UTC on 16 February. The compensating rise of water levels that followed was additionally forced by veering westerly winds. However, already around noon on 16 February, the wind backed as the other low pressure trough advanced, causing water levels to fall. Levels in the eastern part of the coast dropped first, at 13 UTC, and in the western part from about 17 UTC. The minima had the same

53 52 Negative Surges in the Southern Baltic Sea time pattern: the deepest minimum of 425 cm occurred at Sassnitz on 17 February, at 04 UTC. Both Warnemünde and Wismar recorded minima just below 440 cm at about 08 UTC. The minima in the eastern part of the coast were hardly noticeable as the winds veered northwest to northeast between 03 and 04 UTC, causing an immediate rise of water levels. Fig a Pressure pattern and wind field over the Baltic Sea on 16 February 1996, 00 UTC 540 February water level [cm] Wismar Warnemünde Sassnitz winouj cie Kołobrzeg MSL Fig b Variations of sea level decrease during the storm of February 1996

54 Most severe negative surges on the southern Baltic Sea coast December 1999 Meteorological situation At the end of November, as a stationary anticyclone was centred over southern Europe, a succession of low pressure centres travelled across northern Europe. This provoked very strong winds in the northern Baltic Sea region which calmed only temporarily. On 1 December, one of the depressions moved eastward across central Scandinavia and the Gulf of Bothnia, deepening rapidly, with 953 hpa measured in its centre when it reached Finland at 09 UTC. The depression continued tracking toward the White Sea, filling. The low pressure trough with its associated fronts provoked a southerly to southwesterly storm as early as the night of 30 November. Wind force reached more than 8 Bft. In the afternoon of 1 December, winds behind the cold front veered west to northwest and became increasingly gusty (Fig a). On 2 December and in the morning of 3 December, winds backed and calmed to 7 5 Bft. In the meantime, however, another active depression, with 995 hpa in its centre, appeared northwest of Ireland after midnight on 3 December. Moving quickly east across Scotland and the North Sea, the depression, now with an atmospheric pressure of 953 hpa, entered the Skagerrak at 21 UTC on 3 December. The centre slowed over Denmark and stopped, deepening, then continued across southern Sweden and the Baltic Sea. It did not begin to fill until it reached the Latvian coast on 4 December, at 06 UTC, continuing on its eastward track (Fig b). Along its whole track across the North Sea, Scandinavia and the Baltic Sea, the depression was accompanied by hurricane-like winds. The passage of the frontal system resulted in a S-SW storm. After the cold front had passed toward noon on 4 December, the storm veered west, then northwest, increasing considerably in gustiness. The intensity of the storm in the whole southwestern area of the Baltic Sea, from the Sounds to the coasts of Kołobrzeg, reached and at times exceeded 9 to 10 Bft. In the eastern part of the coast the storm was less violent. It was not until the late hours of 4 December that the storm calmed down slowly. and increased to 8 9 Bft, reaching 10 Bft in gusts and dominating the entire Baltic Sea region. Around midnight on 7 December, the winds calmed down, veering slowly (Fig c). Hydrological response of sea level Towards the end of November, water levels oscillated around the mean values in the western part of the Baltic Sea coast. Levels began to decrease in the afternoon of 30 November due to strong offshore winds. Water levels remained at their minimum until the morning hours of 1 December, when the wind veered onshore and decreased. The minimum water levels were first reached in the eastern sections of the coast: 416 cm in Kołobrzeg between 02 and 06 UTC, 385 cm in Świnoujście around 08 UTC, 377 cm at Sassnitz around 03 UTC, 359 cm at Warnemünde between 9 and 10 UTC, and 332 cm at Wismar around 09 UTC. Even deeper minima were forced by the storm of 3 and 4 December. In the western part of the coast, water levels began to fall earlier than in the east because the hurricane-like offshore winds continued for a longer time over the western Baltic Sea. As usual, deeper minima were recorded by the westernmost gauges: 309 cm and 333 cm in Wismar and Warnemünde, respectively, between 9 and 10 UTC, 364 cm at Sassnitz, and 379 cm at Świnoujście between 7 and 8 UTC. In Kołobrzeg, where the wind was less severe and veered first, the minimum of 456 cm was reached between 5 and 6 UTC. Those two very deep drops of sea levels were followed by a third one hardly two days later. When the moderate westerly winds, which calmed down and became variable later on 5 December, backed again southwest in the morning of 6 December and increased to 8 9 Bft, sea levels responded immediately and began to fall toward noon on 6 December. Minima were reached between 18 UTC on 6 and 02 UTC on 7 December. The lowest value in Wismar was close to 380 cm, and the level in Warnemünde was just below 400 cm. The other gauges recorded water levels between 415 cm and 450 cm. The compensating increase which followed was assisted by a slight veering of the wind. On 5 December, moderate westerly winds becoming later variable prevailed over the Baltic Sea. On 6 December, another large low pressure trough approached from the British Isles. Early on 6 December, the winds backed southwest

55 54 Negative Surges in the Southern Baltic Sea Fig a Route of the low pressure centre from 29 November 18 UTC to 2 December 06 UTC, pressure pattern and wind field over the Baltic Sea on 1 December 1999, 00 UTC Fig b Route of the low pressure centre from 3 December 00 UTC to 5 December 00 UTC, pressure pattern and wind field over the Baltic Sea on 4 December 1999, 00 UTC

56 Most severe negative surges on the southern Baltic Sea coast 55 Fig c Pressure pattern and wind field over the Baltic Sea on 6 December 1999, 18 UTC 540 November-December water level [cm] Wismar Warnemünde Sassnitz winouj cie Kołobrzeg MSL Fig d Variations of sea level decrease during the storm of 1 4 December 1999

57 56 Negative Surges in the Southern Baltic Sea December water level [cm] Wismar Warnemünde Sassnitz winouj cie Ko obrzeg MSL Fig e Variations of sea level decrease during the storm of 6 7 December November 2001 Meteorological situation On the days preceding the surge, as northwesterly air flow prevailed over the Baltic Sea, a depression developed near the southeast coast of Greenland. Initially tracking east, the low pressure centre then moved quickly southeastward toward northern Norway. It then tracked across the northern part of the Gulf of Bothnia and central Finland, which it left late on 15 November. Continuing in southeastern direction, the low pressure centre crossed Lake Ladoga, filling in the area southeast of this basin around noon on 16 November. As the pressure trough associated with this centre moved across Scandinavia and the Baltic Sea, the moderate northerly winds prevailing in the western Baltic backed west, then southwest, as wind speeds increased. Early on 15 November, winds reached 7 Bft in the entire Baltic Sea region and soon increased to 8 9 Bft. Between 14 and 22 UTC on 15 November, the cold front crossed the southern Baltic coast, first in the east, and about 9 hours later in the west. Behind the cold front, winds veered northwest in onshore directions, calming only over the western and partly over the southern Baltic Sea, while the central, northern and eastern regions of the Baltic remained under the influence of stormy northerly winds (Fig a). Hydrological response of sea level When early on 15 November the low pressure trough was moving southeast, the stormy winds backed in offshore directions, causing sea levels to fall gradually and nearly simultaneously along the whole southern coast, first at the easternmost water gauges. Thus, the minimum value at Kołobrzeg was 456 cm at about 15 UTC, at Świnoujście 421 cm, and at Sassnitz 407 cm, both around 18 UTC. At Warnemünde, 396 cm was measured at about 20 UTC, and at Wismar 365 cm at 21 UTC (Fig b).

58 Most severe negative surges on the southern Baltic Sea coast 57 Fig a Route of the depression centre from 14 November 18 UTC to 16 November 06 UTC, 2001, pressure pattern and wind field over the Baltic Sea on 15 November 2001, 12 UTC 540 November water level [cm] Wismar Warnemünde Sassnitz winouj cie Kołobrzeg MSL Fig b Variations of sea level decrease during the storm of November 2001

59 58 Negative Surges in the Southern Baltic Sea December 2001 Meteorological situation On 20 December, moderate northwesterly air flow prevailed over Scandinavia and the Baltic Sea. In the course of this day, a low pressure centre moved southeast from the Norwegian Sea, deepening and meandering as it crossed southern Norway and southern Sweden, where it arrived on 21 December at 00 UTC. It took another 24 hours for this slow-moving low pressure centre to cover the distance from southern Sweden to the southern Gulf of Riga. On 22 December, the centre backed east-northeast, continuing on its way across western Russia, where it filled. The deep low pressure trough and the frontal system that accompanied the slowmoving centre provoked a northerly storm on 20 December which, in the afternoon and evening of that day, backed west to southwest over the western and southern parts of the Baltic Sea. As the southwesterly storm increased to 7 9 Bft over the southwestern basins of the Baltic Sea, westerly and northwesterly wind directions still prevailed in its northeastern part. It was not until the morning of 21 December that the wind gradually veered northwest in the whole area, beginning in the eastern basins of the Baltic Sea. Hydrological response of sea level In the afternoon of 20 December, the northerly storm backed west, now blowing alongshore and calming down slightly in the southwestern part of the Baltic Sea. The water masses that had accumulated at the coast began flowing back, causing water levels to fall slowly. As the wind continued backing in offshore directions, water levels dropped at a faster rate, and the minima in this section of the coast were reached between 06 and 12 UTC on 21 December, beginning with the eastern gauges. The minimum of 427 cm at Kołobrzeg was recorded between 05 and 06 UTC, 393 cm at Świnoujście around 06 UTC, 407 cm at Sassnitz around 07 UTC, 375 cm at Warnemünde and 356 cm at Wismar, both between 08 and 09 UTC. The minima were rather flat because the wind did not increase and veer to onshore directions until around noon, when water levels began to rise again. Fig a Route of the depression centre from 06 UTC on 20 to 12 UTC on 22 December 2001, pressure pattern and wind field over the Baltic Sea on 21 December 2001, 00 UTC

60 Most severe negative surges on the southern Baltic Sea coast December water level [cm] Wismar Warnemünde Sassnitz winouj cie Kołobrzeg MSL Fig b Variations of sea level decrease during the storm surge of 20 to 21 December, January 2005 Meteorological situation Late on 7 January, an active low pressure centre formed west of Ireland in the westerly air flow over Europe. In the course of 8 January, the low crossed the Norwegian Sea, southern Norway and central Sweden, deepening, and reached the Åland Islands at 00 UTC on 9 January, with 961 hpa measured in its centre. At 03 UTC, the centre entered southern Finland and, slowing down, meandered toward the area north of Lake Ladoga, where it arrived around 12 UTC. From there, the low veered southeast, filling soon. The frontal system associated with the low initially did not influence the wind direction as it crossed the Baltic Sea region, but behind the warm front tracking across the Baltic Sea in the morning of 7 January, the strong westerly wind soon backed. On 8 January, as the fast moving centre deepened quickly and the pressure gradient was steepening, the southwesterly storm gradually increased in severity, reaching 10 Bft between 21 UTC on 8 January and 03 UTC on 9 January as the occluded front advanced east. The strong wind later veered west and gradually weakened towards evening (Fig a). Hydrological response of sea level In spite of the strong winds, sea levels remained close to the mean values until around noon on 8 January. They began to fall around 18 UTC, after the strong wind had veered to southwesterly directions. In response to the heaviest phase of the west-southwesterly storm behind the occluded front, levels remained below 380 cm from 00 UTC to 10 UTC on 9 January in the western part of the coast. The recorded minima were: 352 cm in Wismar at 07 UTC, 379 cm in Warnemünde and 403 cm in Sassnitz, both at about 04 UTC, and 410 cm in Świnoujście at 05 UTC. The variations of sea level values between 12 UTC on 8 January and 12 UTC on 9 January in Kołobrzeg could not be recorded due to a malfunction of the gauge.

61 60 Negative Surges in the Southern Baltic Sea Fig a Route of the low pressure centre from 7 January 18 UTC to 10 January 00 UTC 2005, pressure pattern and wind field over the Baltic Sea, 9 January, 00 UTC, January water level [cm] Wismar Warnemünde Sassnitz winouj cie Kołobrzeg MSL Fig b Variations of sea level decrease during the storm surge of 8 to 9 January, 2005

Low Sea Level Occurrence of the Southern Baltic Sea Coast

Low Sea Level Occurrence of the Southern Baltic Sea Coast International Journal on Marine Navigation and Safety of Sea Transportation Low Sea Level Occurrence of the Southern Baltic Sea Coast Volume 4 Number 2 June 2010 I. Stanisławczyk, B. Kowalska & M. Mykita

More information

Development of Sea Surface Temperature (SST) in the Baltic Sea 2012

Development of Sea Surface Temperature (SST) in the Baltic Sea 2012 Development of Sea Surface Temperature (SST) in the Baltic Sea 2012 Authors: Herbert Siegel and Monika Gerth, Leibniz Institute for Baltic Sea Research Warnemünde (IOW) Key message The year 2012 was characterized

More information

Wave climate in the Baltic Sea 2013

Wave climate in the Baltic Sea 2013 Wave climate in the Baltic Sea 2013 Authors: Heidi Pettersson, Marine Research, Finnish Meteorological Institute Helma Lindow, Swedish Meteorological and Hydrological Institute Thorger Brüning, Bundesamt

More information

Wave climate in the Baltic Sea 2010

Wave climate in the Baltic Sea 2010 Wave climate in the Baltic Sea 2010 Authors: Heidi Pettersson, Marine Research, Finnish Meteorological Institute Helma Lindow, Swedish Meteorological and Hydrological Institute Dieter Schrader, Bundesamt

More information

Wave climate in the Baltic Sea 2014

Wave climate in the Baltic Sea 2014 Wave climate in the Baltic Sea 2014 Authors: Heidi Pettersson, Marine Research, Finnish Meteorological Institute Helma Lindow, Swedish Meteorological and Hydrological Institute Thorger Brüning, Bundesamt

More information

The ocean water is dynamic. Its physical

The ocean water is dynamic. Its physical CHAPTER MOVEMENTS OF OCEAN WATER The ocean water is dynamic. Its physical characteristics like temperature, salinity, density and the external forces like of the sun, moon and the winds influence the movement

More information

The ice season

The ice season The ice season 2010-2011 Author: Jouni Vainio 1 Co-authors: Patrick Eriksson 1, Natalija Schmelzer 2, Jürgen Holfort 2, Torbjörn Grafström 3, Amund E.B. Lindberg 3, Lisa Lind 3, Jörgen Öberg 3, Andris

More information

Chapter 10 Lecture Outline. The Restless Oceans

Chapter 10 Lecture Outline. The Restless Oceans Chapter 10 Lecture Outline The Restless Oceans Focus Question 10.1 How does the Coriolis effect influence ocean currents? The Ocean s Surface Circulation Ocean currents Masses of water that flow from one

More information

SURFACE CURRENTS AND TIDES

SURFACE CURRENTS AND TIDES NAME SURFACE CURRENTS AND TIDES I. Origin of surface currents Surface currents arise due to the interaction of the prevailing wis a the ocean surface. Hence the surface wi pattern (Figure 1) plays a key

More information

Atmospheric Waves James Cayer, Wesley Rondinelli, Kayla Schuster. Abstract

Atmospheric Waves James Cayer, Wesley Rondinelli, Kayla Schuster. Abstract Atmospheric Waves James Cayer, Wesley Rondinelli, Kayla Schuster Abstract It is important for meteorologists to have an understanding of the synoptic scale waves that propagate thorough the atmosphere

More information

Currents measurements in the coast of Montevideo, Uruguay

Currents measurements in the coast of Montevideo, Uruguay Currents measurements in the coast of Montevideo, Uruguay M. Fossati, D. Bellón, E. Lorenzo & I. Piedra-Cueva Fluid Mechanics and Environmental Engineering Institute (IMFIA), School of Engineering, Research

More information

NordFoU: External Influences on Spray Patterns (EPAS) Report 16: Wind exposure on the test road at Bygholm

NordFoU: External Influences on Spray Patterns (EPAS) Report 16: Wind exposure on the test road at Bygholm NordFoU: External Influences on Spray Patterns (EPAS) Report 16: Wind exposure on the test road at Bygholm Jan S. Strøm, Aarhus University, Dept. of Engineering, Engineering Center Bygholm, Horsens Torben

More information

EXISTING AND PLANNED STRATEGIES AND ACTIONS CONNECTED WITH COASTAL PROTECTION IN ASPECT OF PREDICTED SEA LEVEL RISE

EXISTING AND PLANNED STRATEGIES AND ACTIONS CONNECTED WITH COASTAL PROTECTION IN ASPECT OF PREDICTED SEA LEVEL RISE EXISTING AND PLANNED STRATEGIES AND ACTIONS CONNECTED WITH COASTAL PROTECTION IN ASPECT OF PREDICTED SEA LEVEL RISE Andrzej Cieślak Long term coastal protection strategy In 2000 a new 1 Polish long term

More information

9/25/2014. Scales of Atmospheric Motion. Scales of Atmospheric Motion. Chapter 7: Circulation of the Atmosphere

9/25/2014. Scales of Atmospheric Motion. Scales of Atmospheric Motion. Chapter 7: Circulation of the Atmosphere Chapter 7: Circulation of the Atmosphere The Atmosphere: An Introduction to Meteorology, 12 th Lutgens Tarbuck Lectures by: Heather Gallacher, Cleveland State University Scales of Atmospheric Motion Small-

More information

2. Water levels and wave conditions. 2.1 Introduction

2. Water levels and wave conditions. 2.1 Introduction 18 2. Water levels and wave conditions 2.1 Introduction This Overtopping Manual has a focus on the aspects of wave run-up and wave overtopping only. It is not a design manual, giving the whole design process

More information

Julebæk Strand. Effect full beach nourishment

Julebæk Strand. Effect full beach nourishment Julebæk Strand Effect full beach nourishment Aim of Study This study is a part of the COADAPT funding and the aim of the study is to analyze the effect of beach nourishment. In order to investigate the

More information

What happened to the South Coast El Niño , squid catches? By M J Roberts Sea Fisheries Research Institute, Cape Town

What happened to the South Coast El Niño , squid catches? By M J Roberts Sea Fisheries Research Institute, Cape Town What happened to the South Coast El Niño 1997-98, squid catches? By M J Roberts Sea Fisheries Research Institute, Cape Town Introduction FROM ALL ACCOUNTS, the intense 1997-98 c impacted most regions in

More information

Chapter. Air Pressure and Wind

Chapter. Air Pressure and Wind Chapter Air Pressure and Wind 19.1 Understanding Air Pressure Air Pressure Defined Air pressure is the pressure exerted by the weight of air. 19.1 Understanding Air Pressure Air Pressure Defined Air pressure

More information

WAVE PROPAGATION DIRECTIONS UNDER REAL SEA STATE CONDITIONS. Joachim Griine 1

WAVE PROPAGATION DIRECTIONS UNDER REAL SEA STATE CONDITIONS. Joachim Griine 1 WAVE PROPAGATION DIRECTIONS UNDER REAL SEA STATE CONDITIONS Abstract Joachim Griine 1 This paper deals with the analysis of wave propagation directions from wave climate measurements in field. A simple

More information

Technical Brief - Wave Uprush Analysis 129 South Street, Gananoque

Technical Brief - Wave Uprush Analysis 129 South Street, Gananoque Technical Brief - Wave Uprush Analysis 129 South Street, Gananoque RIGGS ENGINEERING LTD. 1240 Commissioners Road West Suite 205 London, Ontario N6K 1C7 June 12, 2013 Table of Contents Section Page Table

More information

Study of Passing Ship Effects along a Bank by Delft3D-FLOW and XBeach1

Study of Passing Ship Effects along a Bank by Delft3D-FLOW and XBeach1 Study of Passing Ship Effects along a Bank by Delft3D-FLOW and XBeach1 Minggui Zhou 1, Dano Roelvink 2,4, Henk Verheij 3,4 and Han Ligteringen 2,3 1 School of Naval Architecture, Ocean and Civil Engineering,

More information

APPENDIX B NOAA DROUGHT ANALYSIS 29 OCTOBER 2007

APPENDIX B NOAA DROUGHT ANALYSIS 29 OCTOBER 2007 APPENDIX B NOAA DROUGHT ANALYSIS 29 OCTOBER 2007 ENSO Cycle: Recent Evolution, Current Status and Predictions Update prepared by Climate Prediction Center / NCEP October 29, 2007 Outline Overview Recent

More information

Technical Brief - Wave Uprush Analysis Island Harbour Club, Gananoque, Ontario

Technical Brief - Wave Uprush Analysis Island Harbour Club, Gananoque, Ontario Technical Brief - Wave Uprush Analysis RIGGS ENGINEERING LTD. 1240 Commissioners Road West Suite 205 London, Ontario N6K 1C7 October 31, 2014 Table of Contents Section Page Table of Contents... i List

More information

3. DYNAMICS OF GLOBAL CLIMATIC INDICES AND MAIN COMMERCIAL CATCHES

3. DYNAMICS OF GLOBAL CLIMATIC INDICES AND MAIN COMMERCIAL CATCHES 11 3. DYNAMICS OF GLOBAL CLIMATIC INDICES AND MAIN COMMERCIAL CATCHES An important question is whether the main commercial stock production is affected by common factors, which also control the synchronous

More information

Chapter 22, Section 1 - Ocean Currents. Section Objectives

Chapter 22, Section 1 - Ocean Currents. Section Objectives Chapter 22, Section 1 - Ocean Currents Section Objectives Intro Surface Currents Factors Affecting Ocean Currents Global Wind Belts (you should draw and label a diagram of the global wind belts) The Coriolis

More information

Diminished Windstorm Frequency in Southwest British Columbia and a Possible Association With the Pacific Decadal Oscillation Regime Shift of

Diminished Windstorm Frequency in Southwest British Columbia and a Possible Association With the Pacific Decadal Oscillation Regime Shift of Diminished Windstorm Frequency in Southwest British Columbia and a Possible Association With the Pacific Decadal Oscillation Regime Shift of 1976-77 Mantua, N. M. Wolf Read PhD Program Forest Science University

More information

Identification of climate related hazards at the Baltic Sea area

Identification of climate related hazards at the Baltic Sea area Journal of Polish Safety and Reliability Association Summer Safety and Reliability Seminars, Volume 7, Number 1, 2016 Jakusik Ewa Institute of Meteorology and Water Management - NRI, Warsaw, Poland Kołowrocki

More information

THE WAVE CLIMATE IN THE BELGIAN COASTAL ZONE

THE WAVE CLIMATE IN THE BELGIAN COASTAL ZONE THE WAVE CLIMATE IN THE BELGIAN COASTAL ZONE Toon Verwaest, Flanders Hydraulics Research, toon.verwaest@mow.vlaanderen.be Sarah Doorme, IMDC, sarah.doorme@imdc.be Kristof Verelst, Flanders Hydraulics Research,

More information

The Impact on Great South Bay of the Breach at Old Inlet Charles N. Flagg School of Marine and Atmospheric Sciences, Stony Brook University

The Impact on Great South Bay of the Breach at Old Inlet Charles N. Flagg School of Marine and Atmospheric Sciences, Stony Brook University The Impact on Great South Bay of the Breach at Old Inlet Charles N. Flagg School of Marine and Atmospheric Sciences, Stony Brook University The previous report provided a detailed look at the conditions

More information

A Hare-Lynx Simulation Model

A Hare-Lynx Simulation Model 1 A Hare- Simulation Model What happens to the numbers of hares and lynx when the core of the system is like this? Hares O Balance? S H_Births Hares H_Fertility Area KillsPerHead Fertility Births Figure

More information

OPERATIONAL AMV PRODUCTS DERIVED WITH METEOSAT-6 RAPID SCAN DATA. Arthur de Smet. EUMETSAT, Am Kavalleriesand 31, D Darmstadt, Germany ABSTRACT

OPERATIONAL AMV PRODUCTS DERIVED WITH METEOSAT-6 RAPID SCAN DATA. Arthur de Smet. EUMETSAT, Am Kavalleriesand 31, D Darmstadt, Germany ABSTRACT OPERATIONAL AMV PRODUCTS DERIVED WITH METEOSAT-6 RAPID SCAN DATA Arthur de Smet EUMETSAT, Am Kavalleriesand 31, D-64295 Darmstadt, Germany ABSTRACT EUMETSAT started its Rapid Scanning Service on September

More information

Climatology of the 10-m wind along the west coast of South American from 30 years of high-resolution reanalysis

Climatology of the 10-m wind along the west coast of South American from 30 years of high-resolution reanalysis Climatology of the 10-m wind along the west coast of South American from 30 years of high-resolution reanalysis David A. Rahn and René D. Garreaud Departamento de Geofísica, Facultad de Ciencias Físicas

More information

Surf Survey Summary Report

Surf Survey Summary Report Port Otago Limited 15 Beach Street Port Chalmers Surf Survey Summary Report August 13-September 1 Leigh McKenzie Summary of Surf Locations of Interest Port Otago Ltd is undertaking monitoring of changes

More information

APPENDIX G WEATHER DATA SELECTED EXTRACTS FROM ENVIRONMENTAL DATA FOR BCFS VESSEL REPLACEMENT PROGRAM DRAFT REPORT

APPENDIX G WEATHER DATA SELECTED EXTRACTS FROM ENVIRONMENTAL DATA FOR BCFS VESSEL REPLACEMENT PROGRAM DRAFT REPORT APPENDIX G WEATHER DATA SELECTED EXTRACTS FROM ENVIRONMENTAL DATA FOR BCFS VESSEL REPLACEMENT PROGRAM DRAFT REPORT Prepared for: B.C. Ferries Services Inc. Prepared by: George Roddan, P.Eng. Roddan Engineering

More information

Lecture Outlines PowerPoint. Chapter 15 Earth Science, 12e Tarbuck/Lutgens

Lecture Outlines PowerPoint. Chapter 15 Earth Science, 12e Tarbuck/Lutgens Lecture Outlines PowerPoint Chapter 15 Earth Science, 12e Tarbuck/Lutgens 2009 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for the use of instructors

More information

Air Pressure and Wind

Air Pressure and Wind Air Pressure and Wind 19.1 Understanding Air Pressure Air Pressure Defined Air pressure is the pressure exerted by the weight of air. Air pressure is exerted in all directions down, up, and sideways. The

More information

Shorelines Earth - Chapter 20 Stan Hatfield Southwestern Illinois College

Shorelines Earth - Chapter 20 Stan Hatfield Southwestern Illinois College Shorelines Earth - Chapter 20 Stan Hatfield Southwestern Illinois College The Shoreline A Dynamic Interface The shoreline is a dynamic interface (common boundary) among air, land, and the ocean. The shoreline

More information

Appendix E Mangaone Stream at Ratanui Hydrological Gauging Station Influence of IPO on Stream Flow

Appendix E Mangaone Stream at Ratanui Hydrological Gauging Station Influence of IPO on Stream Flow NZ Transport Agency Peka Peka to North Ōtaki Expressway Hydraulic Investigations for Expressway Crossing of Mangaone Stream and Floodplain Appendix E Mangaone Stream at Ratanui Hydrological Gauging Station

More information

by *) Winfried Siefert

by *) Winfried Siefert CHAPTER 16 SHALLOW WATER WAVE CHARACTERISTICS by *) Winfried Siefert Abstract Prototype data from 24 wave stations on and around the tidal flats south of the Elbe estuary enable us to elaborate special

More information

SECTION 2 HYDROLOGY AND FLOW REGIMES

SECTION 2 HYDROLOGY AND FLOW REGIMES SECTION 2 HYDROLOGY AND FLOW REGIMES In this section historical streamflow data from permanent USGS gaging stations will be presented and discussed to document long-term flow regime trends within the Cache-Bayou

More information

Directed Reading. Section: Ocean Currents. a(n). FACTORS THAT AFFECT SURFACE CURRENTS

Directed Reading. Section: Ocean Currents. a(n). FACTORS THAT AFFECT SURFACE CURRENTS Skills Worksheet Directed Reading Section: Ocean Currents 1. A horizontal movement of water in a well-defined pattern is called a(n). 2. What are two ways that oceanographers identify ocean currents? 3.

More information

FIVE YEARS OF OPERATION OF THE FIRST OFFSHORE WIND RESEARCH PLATFORM IN THE GERMAN BIGHT FINO1

FIVE YEARS OF OPERATION OF THE FIRST OFFSHORE WIND RESEARCH PLATFORM IN THE GERMAN BIGHT FINO1 FIVE YEARS OF OPERATION OF THE FIRST OFFSHORE WIND RESEARCH PLATFORM IN THE GERMAN BIGHT FINO1 Andreas Beeken, DEWI GmbH, Ebertstraße 96, D-26382 Wilhelmshaven Thomas Neumann, DEWI GmbH, Ebertstraße 96,

More information

ENFEN OFFICIAL STATEMENT N Status Warning System: El Niño Coastal Alert 1

ENFEN OFFICIAL STATEMENT N Status Warning System: El Niño Coastal Alert 1 ENFEN OFFICIAL STATEMENT N 21-2015 Status Warning System: El Niño Coastal Alert 1 Note: This translation is provided for convenience, the official version is in Spanish The Multisectoral Committee of the

More information

Wave Setup at River and Inlet Entrances Due to an Extreme Event

Wave Setup at River and Inlet Entrances Due to an Extreme Event Proceedings of International Conference on Violent Flows (VF-2007) Organized by RIAM, Kyushu University, Fukuoka, Japan Wave Setup at River and Inlet Entrances Due to an Extreme Event Xuan Tinh Nguyen

More information

PROPAGATION OF LONG-PERIOD WAVES INTO AN ESTUARY THROUGH A NARROW INLET

PROPAGATION OF LONG-PERIOD WAVES INTO AN ESTUARY THROUGH A NARROW INLET PROPAGATION OF LONG-PERIOD WAVES INTO AN ESTUARY THROUGH A NARROW INLET Takumi Okabe, Shin-ichi Aoki and Shigeru Kato Department of Civil Engineering Toyohashi University of Technology Toyohashi, Aichi,

More information

13. TIDES Tidal waters

13. TIDES Tidal waters Water levels vary in tidal and non-tidal waters: sailors should be aware that the depths shown on the charts do not always represent the actual amount of water under the boat. 13.1 Tidal waters In tidal

More information

INTRODUCTION TO COASTAL ENGINEERING AND MANAGEMENT

INTRODUCTION TO COASTAL ENGINEERING AND MANAGEMENT Advanced Series on Ocean Engineering Volume 16 INTRODUCTION TO COASTAL ENGINEERING AND MANAGEMENT J. William Kamphuis Queen's University, Canada World Scientific Singapore New Jersey London Hong Kong Contents

More information

SAND BOTTOM EROSION AND CHANGES OF AN ACTIVE LAYER THICKNESS IN THE SURF ZONE OF THE NORDERNEY ISLAND

SAND BOTTOM EROSION AND CHANGES OF AN ACTIVE LAYER THICKNESS IN THE SURF ZONE OF THE NORDERNEY ISLAND SAND BOTTOM EROSION AND CHANGES OF AN ACTIVE LAYER THICKNESS IN THE SURF ZONE OF THE NORDERNEY ISLAND Kos'yan R. 1, Kunz H. 2, Podymov l. 3 1 Prof.Dr.,The Southern Branch of the P.P.Shirshov Institute

More information

Sea Ice Characteristics and Operational Conditions for Ships Working in the Western Zone of the NSR

Sea Ice Characteristics and Operational Conditions for Ships Working in the Western Zone of the NSR The Arctic 2030 Project: Feasibility and Reliability of Shipping on the Northern Sea Route and Modeling of an Arctic Marine Transportation & Logistics System 3-rd. Industry Seminar: Sea-Ice & Operational

More information

ENSO Cycle: Recent Evolution, Current Status and Predictions. Update prepared by Climate Prediction Center / NCEP 8 March 2010

ENSO Cycle: Recent Evolution, Current Status and Predictions. Update prepared by Climate Prediction Center / NCEP 8 March 2010 ENSO Cycle: Recent Evolution, Current Status and Predictions Update prepared by Climate Prediction Center / NCEP 8 March 2010 Outline Overview Recent Evolution and Current Conditions Oceanic Niño Index

More information

Oceans and Coasts. Chapter 18

Oceans and Coasts. Chapter 18 Oceans and Coasts Chapter 18 Exploring the oceans The ocean floor Sediments thicken and the age of the seafloor increases from ridge to shore The continental shelf off the northeast United States Constituent

More information

General Coastal Notes + Landforms! 1

General Coastal Notes + Landforms! 1 General Coastal Notes + Landforms! 1 Types of Coastlines: Type Description Primary Coast which is essentially in the same condition when sea level stabilized Coastline after the last ice age, younger.

More information

Atomspheric Waves at the 500hPa Level

Atomspheric Waves at the 500hPa Level Atomspheric Waves at the 5hPa Level Justin Deal, Eswar Iyer, and Bryce Link ABSTRACT Our study observes and examines large scale motions of the atmosphere. More specifically it examines wave motions at

More information

Inlet Management Study for Pass-A-Grille and Bunces Pass, Pinellas County, Florida

Inlet Management Study for Pass-A-Grille and Bunces Pass, Pinellas County, Florida Inlet Management Study for Pass-A-Grille and Bunces Pass, Pinellas County, Florida Final Report Submitted By Ping Wang, Ph.D., Jun Cheng Ph.D., Zachary Westfall, and Mathieu Vallee Coastal Research Laboratory

More information

COASTAL PROTECTION AGAINST WIND-WAVE INDUCED EROSION USING SOFT AND POROUS STRUCTURES: A CASE STUDY AT LAKE BIEL, SWITZERLAND

COASTAL PROTECTION AGAINST WIND-WAVE INDUCED EROSION USING SOFT AND POROUS STRUCTURES: A CASE STUDY AT LAKE BIEL, SWITZERLAND COASTAL PROTECTION AGAINST WIND-WAVE INDUCED EROSION USING SOFT AND POROUS STRUCTURES: A CASE STUDY AT LAKE BIEL, SWITZERLAND Selim M. Sayah 1 and Stephan Mai 2 1. Swiss Federal Institute of Technology

More information

Atmospheric Rossby Waves in Fall 2011: Analysis of Zonal Wind Speed and 500hPa Heights in the Northern and Southern Hemispheres

Atmospheric Rossby Waves in Fall 2011: Analysis of Zonal Wind Speed and 500hPa Heights in the Northern and Southern Hemispheres Atmospheric Rossby Waves in Fall 211: Analysis of Zonal Wind Speed and 5hPa Heights in the Northern and Southern s Samuel Cook, Craig Eckstein, and Samantha Santeiu Department of Atmospheric and Geological

More information

TABLE OF CONTENTS CHAPTER TITLE PAGE LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS LIST OF SYMBOLS LIST OF APPENDICES

TABLE OF CONTENTS CHAPTER TITLE PAGE LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS LIST OF SYMBOLS LIST OF APPENDICES vii TABLE OF CONTENTS CHAPTER TITLE PAGE AUTHOR S DECLARATION DEDICATION ACKNOWLEDGEMENTS ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS LIST OF SYMBOLS LIST OF

More information

CHAPTER 8 ASSESSMENT OF COASTAL VULNERABILITY INDEX

CHAPTER 8 ASSESSMENT OF COASTAL VULNERABILITY INDEX 124 CHAPTER 8 ASSESSMENT OF COASTAL VULNERABILITY INDEX 8.1 INTRODUCTION In order to assess the vulnerability of the shoreline considered under this study against the changing environmental conditions,

More information

Monitoring Cruise Report

Monitoring Cruise Report r/v Gunnar Thorson Monitoring Cruise Report Cruise no.: 228 Time: 7-18 February 25 Area: The Sound, the Kattegat, the Skagerrak, the North Sea, the Belt Sea and the Arkona Sea Ministry of the Environment

More information

MONITORING SEDIMENT TRANSPORT PROCESSES AT MANAVGAT RIVER MOUTH, ANTALYA TURKEY

MONITORING SEDIMENT TRANSPORT PROCESSES AT MANAVGAT RIVER MOUTH, ANTALYA TURKEY COPEDEC VI, 2003 in Colombo, Sri Lanka MONITORING SEDIMENT TRANSPORT PROCESSES AT MANAVGAT RIVER MOUTH, ANTALYA TURKEY Isikhan GULER 1, Aysen ERGIN 2, Ahmet Cevdet YALCINER 3 ABSTRACT Manavgat River, where

More information

The Setting - Climatology of the Hawaiian Archipelago. Link to Video of Maui Waves

The Setting - Climatology of the Hawaiian Archipelago. Link to Video of Maui Waves The Setting - Climatology of the Hawaiian Archipelago Link to Video of Maui Waves What caused this week s weather? What caused this weekend s weather? Today s Objective: Provide overview and description

More information

Sand Bank Passage. Fiji nearshore wave hindcast ' ' 19 00'

Sand Bank Passage. Fiji nearshore wave hindcast ' ' 19 00' Sand Bank Passage Fiji nearshore wave hindcast 1 00' 1 00' 1 30' 1 00' 177 00' 177 30' 17 00' 17 30' 17 30' Figure 1. Location maps of the site. The map on the left shows the region. The map on the right

More information

SCIENTIFIC COMMITTEE SEVENTH REGULAR SESSION August 2011 Pohnpei, Federated States of Micronesia

SCIENTIFIC COMMITTEE SEVENTH REGULAR SESSION August 2011 Pohnpei, Federated States of Micronesia SCIENTIFIC COMMITTEE SEVENTH REGULAR SESSION 9-17 August 2011 Pohnpei, Federated States of Micronesia CPUE of skipjack for the Japanese offshore pole and line using GPS and catch data WCPFC-SC7-2011/SA-WP-09

More information

Geostrophic and Tidal Currents in the South China Sea, Area III: West Philippines

Geostrophic and Tidal Currents in the South China Sea, Area III: West Philippines Southeast Asian Fisheries Development Center Geostrophic and Tidal Currents in the South China Sea, Area III: West Philippines Anond Snidvongs Department od Marine Science, Chulalongkorn University, Bangkok

More information

Atmospheric Rossby Waves Fall 2012: Analysis of Northern and Southern 500hPa Height Fields and Zonal Wind Speed

Atmospheric Rossby Waves Fall 2012: Analysis of Northern and Southern 500hPa Height Fields and Zonal Wind Speed Atmospheric Rossby Waves Fall 12: Analysis of Northern and Southern hpa Height Fields and Zonal Wind Speed Samuel Schreier, Sarah Stewart, Ashley Christensen, and Tristan Morath Department of Atmospheric

More information

A Comparison of the UK Offshore Wind Resource from the Marine Data Exchange. P. Argyle, S. J. Watson CREST, Loughborough University, UK

A Comparison of the UK Offshore Wind Resource from the Marine Data Exchange. P. Argyle, S. J. Watson CREST, Loughborough University, UK A Comparison of the UK Offshore Wind Resource from the Marine Data Exchange P. Argyle, S. J. Watson CREST, Loughborough University, UK Introduction Offshore wind measurements are scarce and expensive,

More information

Section 1. Global Wind Patterns and Weather. What Do You See? Think About It. Investigate. Learning Outcomes

Section 1. Global Wind Patterns and Weather. What Do You See? Think About It. Investigate. Learning Outcomes Chapter 5 Winds, Oceans, Weather, and Climate Section 1 Global Wind Patterns and Weather What Do You See? Learning Outcomes In this section, you will Determine the effects of Earth s rotation and the uneven

More information

The Movement of Ocean Water. Currents

The Movement of Ocean Water. Currents The Movement of Ocean Water Currents Ocean Current movement of ocean water that follows a regular pattern influenced by: weather Earth s rotation position of continents Surface current horizontal movement

More information

Effects of directionality on wind load and response predictions

Effects of directionality on wind load and response predictions Effects of directionality on wind load and response predictions Seifu A. Bekele 1), John D. Holmes 2) 1) Global Wind Technology Services, 205B, 434 St Kilda Road, Melbourne, Victoria 3004, Australia, seifu@gwts.com.au

More information

Meteorology I Pre test for the Second Examination

Meteorology I Pre test for the Second Examination Meteorology I Pre test for the Second Examination MULTIPLE CHOICE 1. A primary reason why land areas warm up more rapidly than water areas is that a) on land, all solar energy is absorbed in a shallow

More information

Weather drivers in South Australia

Weather drivers in South Australia August 2008 Key facts Weather drivers in South Australia Major weather drivers in South Australia are: El Niño - Southern Oscillation frontal systems cut-off lows blocking highs Indian Ocean Dipole cloudbands

More information

CHAPTER 6 DISCUSSION ON WAVE PREDICTION METHODS

CHAPTER 6 DISCUSSION ON WAVE PREDICTION METHODS CHAPTER 6 DISCUSSION ON WAVE PREDICTION METHODS A critical evaluation of the three wave prediction methods examined in this thesis is presented in this Chapter. The significant wave parameters, Hand T,

More information

Kavala Bay. Fiji nearshore wave hindcast ' ' 19 00'

Kavala Bay. Fiji nearshore wave hindcast ' ' 19 00' Kavala Bay Fiji nearshore wave hindcast 1 00' 19 00' 1 30' 19 00' 1 00' 1 30' 1 00' 1 30' 1 30' Figure 1. Location maps of the site. The map on the left shows the region. The map on the right shows the

More information

18.1 Understanding Air Pressure 18.1 Understanding Air Pressure Air Pressure Defined Measuring Air Pressure Air pressure barometer

18.1 Understanding Air Pressure 18.1 Understanding Air Pressure Air Pressure Defined Measuring Air Pressure Air pressure barometer 18.1 Understanding Air Pressure 18.1 Understanding Air Pressure Air Pressure Defined Air pressure is the pressure exerted by the weight of air. Air pressure is exerted in all directions down, up, and sideways.

More information

Mango Bay_Resort. Fiji nearshore wave hindcast ' ' 19 00'

Mango Bay_Resort. Fiji nearshore wave hindcast ' ' 19 00' Mango Bay_Resort Fiji nearshore wave hindcast 1 00' 1 30' 1 00' 177 00' 177 30' 17 00' 17 30' Figure 1. Location maps of the site. The map on the left shows the region. The map on the right shows the island

More information

Leibniz Institute for Baltic Sea Research Warnemünde

Leibniz Institute for Baltic Sea Research Warnemünde INSTITUT FÜR OSTSEEFORSCHUNG WARNEMÜNDE an der Universität Rostock BALTIC SEA RESEARCH INSTITUTE Leibniz Institute for Baltic Sea Research C r u i s e R e p o r t r/v "Elisabeth Mann Borgese" Cruise- No.

More information

Impact of the tides, wind and shelf circulation on the Gironde river plume dynamics

Impact of the tides, wind and shelf circulation on the Gironde river plume dynamics Impact of the tides, wind and shelf circulation on the Gironde river plume dynamics F. Toublanc 1, N. Ayoub 2, P. Marsaleix 3, P. De Mey 2 1 CNES/LEGOS 2 CNRS/LEGOS 3 CNRS/LA, Toulouse, France 5th GODAE

More information

SOME PROPERTIES OF SWELL IN THE SOUTHERN OCEAN. Jon B. Hinwoodil. Deane R. Blackman, and Geoffrey T. Lleonart^3

SOME PROPERTIES OF SWELL IN THE SOUTHERN OCEAN. Jon B. Hinwoodil. Deane R. Blackman, and Geoffrey T. Lleonart^3 SOME PROPERTIES OF SWELL IN THE SOUTHERN OCEAN by Jon B. Hinwoodil. 1 Deane R. Blackman, and Geoffrey T. Lleonart^3 3 SUMMARY Records of pressure from a bottom-resident instrument deployed near the western

More information

Appendix E Cat Island Borrow Area Analysis

Appendix E Cat Island Borrow Area Analysis Appendix E Cat Island Borrow Area Analysis ERDC/CHL Letter Report 1 Cat Island Borrow Area Analysis Multiple borrow area configurations were considered for Cat Island restoration. Borrow area CI1 is located

More information

Wave Breaking and Wave Setup of Artificial Reef with Inclined Crown Keisuke Murakami 1 and Daisuke Maki 2

Wave Breaking and Wave Setup of Artificial Reef with Inclined Crown Keisuke Murakami 1 and Daisuke Maki 2 Wave Breaking and Wave Setup of Artificial Reef with Inclined Crown Keisuke Murakami 1 and Daisuke Maki 2 Beach protection facilities are sometimes required to harmonize with coastal environments and utilizations.

More information

Section 6. The Surface Circulation of the Ocean. What Do You See? Think About It. Investigate. Learning Outcomes

Section 6. The Surface Circulation of the Ocean. What Do You See? Think About It. Investigate. Learning Outcomes Chapter 5 Winds, Oceans, Weather, and Climate Section 6 The Surface Circulation of the Ocean What Do You See? Learning Outcomes In this section, you will Understand the general paths of surface ocean currents.

More information

SCIENCE OF TSUNAMI HAZARDS

SCIENCE OF TSUNAMI HAZARDS SCIENCE OF TSUNAMI HAZARDS ISSN 8755-6839 Journal of Tsunami Society International Volume 31 Number 2 2012 SEA LEVEL SIGNALS CORRECTION FOR THE 2011 TOHOKU TSUNAMI A. Annunziato 1 1 Joint Research Centre,

More information

Equatorial upwelling. Example of regional winds of small scale

Equatorial upwelling. Example of regional winds of small scale Example of regional winds of small scale Sea and land breezes Note on Fig. 8.11. Shows the case for southern hemisphere! Coastal upwelling and downwelling. Upwelling is caused by along shore winds, that

More information

ENSO and monsoon induced sea level changes and their impacts along the Indian coastline

ENSO and monsoon induced sea level changes and their impacts along the Indian coastline Indian Journal of Marine Sciences Vol. 35(2), June 2006, pp. 87-92 ENSO and monsoon induced sea level changes and their impacts along the Indian coastline O.P.Singh* Monsoon Activity Centre, India Meteorological

More information

Chapter 11 Tides. A tidal bore is formed when a tide arrives to an enclosed river mouth. This is a forced wave that breaks.

Chapter 11 Tides. A tidal bore is formed when a tide arrives to an enclosed river mouth. This is a forced wave that breaks. Chapter 11 Tides A tidal bore is formed when a tide arrives to an enclosed river mouth. This is a forced wave that breaks. Tidal range can be very large Tide - rhythmic oscillation of the ocean surface

More information

Chapter 15 SEASONAL CHANGES IN BEACHES OP THE NORTH ATLANTIC COAST OF THE UNITED STATES

Chapter 15 SEASONAL CHANGES IN BEACHES OP THE NORTH ATLANTIC COAST OF THE UNITED STATES Chapter 15 SEASONAL CHANGES IN BEACHES OP THE NORTH ATLANTIC COAST OF THE UNITED STATES By John M. Darling Hydraulic Engineer, Research Division U. S. Army Coastal Engineering Research Center Corps of

More information

CHAPTER 134 INTRODUCTION

CHAPTER 134 INTRODUCTION CHAPTER 134 NEW JETTIES FOR TUNG-KANG FISHING HARBOR, TAIWAN Chi-Fu Su Manager Engineering Department Taiwan Fisheries Consultants, Inc. Taipei, Taiwan INTRODUCTION Tung-Kang Fishing Harbor, which is about

More information

RESEARCH AND ENGINEERING FOR ICZM IN POLAND

RESEARCH AND ENGINEERING FOR ICZM IN POLAND ICZM in a climate change perspective Important issues for the Baltic Sea Lubiatowo, June 2008 RESEARCH AND ENGINEERING FOR ICZM IN POLAND Rafał Ostrowski, Marek Skaja & Marek Szmytkiewicz Institute of

More information

Monitoring Cruise Report

Monitoring Cruise Report r/v Gunnar Thorson Monitoring Cruise Report Cruise no.: 214 Time: 1-19 February 23 Area: The Sound, the Kattegat, the Skagerrak, the North Sea, the Belt Sea and the Arkona Sea Ministry of the Environment

More information

IMPACTS OF COASTAL PROTECTION STRATEGIES ON THE COASTS OF CRETE: NUMERICAL EXPERIMENTS

IMPACTS OF COASTAL PROTECTION STRATEGIES ON THE COASTS OF CRETE: NUMERICAL EXPERIMENTS IMPACTS OF COASTAL PROTECTION STRATEGIES ON THE COASTS OF CRETE: NUMERICAL EXPERIMENTS Tsanis, I.K., Saied, U.M., Valavanis V. Department of Environmental Engineering, Technical University of Crete, Chania,

More information

Figure 4, Photo mosaic taken on February 14 about an hour before sunset near low tide.

Figure 4, Photo mosaic taken on February 14 about an hour before sunset near low tide. The Impact on Great South Bay of the Breach at Old Inlet Charles N. Flagg and Roger Flood School of Marine and Atmospheric Sciences, Stony Brook University Since the last report was issued on January 31

More information

The Great Coastal Gale of 2007 from Coastal Storms Program Buoy 46089

The Great Coastal Gale of 2007 from Coastal Storms Program Buoy 46089 The Great Coastal Gale of 2007 from Coastal Storms Program Buoy 46089 Richard L. Crout, Ian T. Sears, and Lea K. Locke NOAA National Data Buoy Center 1007 Balch Blvd. Stennis Space Center, MS 39529 USA

More information

OECS Regional Engineering Workshop September 29 October 3, 2014

OECS Regional Engineering Workshop September 29 October 3, 2014 B E A C H E S. M A R I N A S. D E S I G N. C O N S T R U C T I O N. OECS Regional Engineering Workshop September 29 October 3, 2014 Coastal Erosion and Sea Defense: Introduction to Coastal Dynamics David

More information

HARBOUR SEDIMENTATION - COMPARISON WITH MODEL

HARBOUR SEDIMENTATION - COMPARISON WITH MODEL HARBOUR SEDIMENTATION - COMPARISON WITH MODEL ABSTRACT A mobile-bed model study of Pointe Sapin Harbour, in the Gulf of St. Lawrence, resulted in construction of a detached breakwater and sand trap to

More information

ABNORMALLY HIGH STORM WAVES OBSERVED ON THE EAST COAST OF KOREA

ABNORMALLY HIGH STORM WAVES OBSERVED ON THE EAST COAST OF KOREA ABNORMALLY HIGH STORM WAVES OBSERVED ON THE EAST COAST OF KOREA WEON MU JEONG 1 ; SANG-HO OH ; DONGYOUNG LEE 3 ; KYUNG-HO RYU 1 Coastal Engineering Research Department, Korea Ocean Research and Development

More information

ESTIMATION OF THE DESIGN WIND SPEED BASED ON

ESTIMATION OF THE DESIGN WIND SPEED BASED ON The Seventh Asia-Pacific Conference on Wind Engineering, November 8-12, 2009, Taipei, Taiwan ESTIMATION OF THE DESIGN WIND SPEED BASED ON UNCERTAIN PARAMETERS OF THE WIND CLIMATE Michael Kasperski 1 1

More information

COMPARISON OF CONTEMPORANEOUS WAVE MEASUREMENTS WITH A SAAB WAVERADAR REX AND A DATAWELL DIRECTIONAL WAVERIDER BUOY

COMPARISON OF CONTEMPORANEOUS WAVE MEASUREMENTS WITH A SAAB WAVERADAR REX AND A DATAWELL DIRECTIONAL WAVERIDER BUOY COMPARISON OF CONTEMPORANEOUS WAVE MEASUREMENTS WITH A SAAB WAVERADAR REX AND A DATAWELL DIRECTIONAL WAVERIDER BUOY Scott Noreika, Mark Beardsley, Lulu Lodder, Sarah Brown and David Duncalf rpsmetocean.com

More information

Ocean Currents Unit (4 pts)

Ocean Currents Unit (4 pts) Name: Section: Ocean Currents Unit (Topic 9A-1) page 1 Ocean Currents Unit (4 pts) Ocean Currents An ocean current is like a river in the ocean: water is flowing traveling from place to place. Historically,

More information

Critical Gust Pressures on Tall Building Frames-Review of Codal Provisions

Critical Gust Pressures on Tall Building Frames-Review of Codal Provisions Dr. B.Dean Kumar Dept. of Civil Engineering JNTUH College of Engineering Hyderabad, INDIA bdeankumar@gmail.com Dr. B.L.P Swami Dept. of Civil Engineering Vasavi College of Engineering Hyderabad, INDIA

More information

Lecture 24. El Nino Southern Oscillation (ENSO) Part 1

Lecture 24. El Nino Southern Oscillation (ENSO) Part 1 Lecture 24 El Nino Southern Oscillation (ENSO) Part 1 The most dominant phenomenon in the interannual variation of the tropical oceanatmosphere system is the El Nino Southern Oscillation (ENSO) over the

More information