Flooding along English Channel coast due to long-period swell waves

Transcription

1 Flooding along English Channel coast due to long-period swell waves Andrew Sibley 1 and Dave Cox 2 1 Met Office, Hazard Centre, Exeter 2 Met Office, Flood Forecasting Centre, Exeter Introduction Long-period swell waves have occasionally caused flooding in towns along the English Channel coast, for instance Seaton and Portland in Lyme Bay, Hurst Beach in Christchurch Bay, and South Hayling Beach on Hayling Island. The beaches affected tend to be composed of shingle with a fairly steep slope, and these characteristics seem to be significant. The sudden onset of swell waves can also be hazardous for bathers, swimmers and walkers on other beaches around the southwest coast. These waves sometimes develop in association with trapped fetches: that is where the speed of the low pressure centre, with associated very strong winds on the southern flank, move roughly in line with the main wave group induced on the ocean surface. Bowyer and MacAfee (2005) have reported on work by the Canadian Hurricane Centre that seeks to model trapped fetch waves in association with tropical and extratropical storms on the eastern seaboard of America. They note that the development of such events is highly sensitive to the speed, movement and strength of the storm system, and the gradient wind speed, in relation to the speed of the group wave speed. The largest swell waves develop on the right flank of the direction of movement of the low pressure. If moving from west to east then the largest waves form on the southern flank. There is an optimum velocity of movement of the storm system in relation to the group wave speed and the period of the fetch. So, over a 48h period, with a surface wind speed of 60kn, the storm system would need to match a speed of 26 27kn for optimal wave growth; over 72h it is about 28kn (Bowyer and MacAfee, 2005). In a fully developed sea-state the speed of individual waves over deep water approximates the wind speed. However, the group wavespeed is roughly half the single wavespeed, with individual waves moving through the wave group. So in trapped fetch events the speed of the low pressure centre needs to be about half the mean wind speed at the sea surface. Over long distances it is necessary for the low centre to move relative to the curvature of the Earth. This has the effect of building the waves continually over a long period, perhaps in excess of 48h. Long-period swell waves may also develop and be maintained where there is a strong, fairly straight wind flow lasting for perhaps 24 48h. The developed individual wave period is typically between 12 and 20s, and often greater than that of locally generated wind waves. The UK sometimes receives long-period swell waves from extratropical storms developing in the western Atlantic, southeast of Newfoundland, but the energy dissipates somewhat over distance: that is unless it is maintained by the forcing low-level winds keeping pace with the swell waves. This may happen with rapid cyclogenesis in the northwest Atlantic followed by progression of the Figure 1. Synoptic analyses October low pressure centre so that the low-level wind speed and movement of the low centre is harmonised with the wave group speed. Once in the English Channel, it would seem that such waves are refracted towards the English coast by the Hurd Deep that lies west to east in the middle of the Channel, but are also refracted further as they come into the shallow water near the coast (Lapworth, 2011). In shallow water the wave speed c = gd (where g is gravity, d is water depth), so waves moving into shallower water near the coast will be slowed, and the wave will appear to bend towards the coast. The wave period T remains constant as the speed slows, so the wavelength L must shorten (L = ct). Because wave energy is conserved (ignoring the effect of friction) the wave will also grow proportionally in height. The associated coastal flooding from such travelling waves often correlates with tidal surges and the close proximity of fairly deep low pressure centres, but not necessarily with locally generated high seas. Because of Weather March 2014, Vol. 69, No. 3 59

2 Weather March 2014, Vol. 69, No. 3 English Channel coastal flooding Table 1 Time, position, distance travelled and estimated average speed of movement of low centres for four of the events: February 1979, January 1986, October 2006, February Event Date/time (UTC) Latitude/longitude km kmh 1 /knots February / N, 53 W 11/ N, 38 W /29 12/ N, 18 W /33 13/ N, 03 W /25 January / N, 38 W 01/ N, 19 W /30 02/ N, 04 W /24 October / N, 26 W 23/ N, 10 W /29 24/ N, 03 W /27 February / N, 55 W 14/ N, 33 W /42 15/ N, 25 W /13 the remote generation of large waves the risk of resultant coastal flooding needs to be carefully monitored as it may not be immediately obvious. It is necessary therefore to try and improve the forecasting of these events. One relatively recent event occurred on 24 October We will discuss this event first, then look at the similarities and differences with a number of other events and seek to draw out wider lessons. Then we will look at modelling developments for the more recent events. Events of 24 October 2006 The BBC reported damage to coastal structures, and flooded cars parked immediately behind the sea front at Seaton in Devon, on the morning of 24 October 2006 (BBC News, 2006). Several beach huts on the western side of the promenade were damaged by wave activity. Swell wave heights near high tide (around 0700 UTC) were reported to be between 2.4 and 3.0m by eyewitnesses. The wave energy ran up the shingle beach and overtopped the promenade sea defences, although a concrete slipway may have aided the overtopping here. Flooding occurred behind the sea wall, with a depth of accumulated water reported of almost 1m. The seawater was able to breach the gate opening of the protective sea wall, although beach huts were sited in front of the wall, and spray and some pebbles were washed over the top as well. This wall was built after previous coastal flooding events, particularly that of February 1979 (as discussed below). With this event the low pressure centre passed along the middle of the English Channel around 24/0000 UTC. So by the time of the period of coastal flooding Lyme Bay was in a strong offshore northwesterly wind flow, even reaching gale force (320 ; 34kn, gusts 42kn) at 0600 UTC at the Channel Light Vessel (49.9 N, 2.9 W). However, there may still have been a positive wind component acting to help maintain the wave energy, as the wave direction along the English Channel was roughly perpendicular to the wind velocity. The low centre movement is shown in Figure 1, with the average speed approximately 27 29kn (Table 1). This event occurred with moderately high tides and a positive surge of 10 20cm, although there was still a good margin of 40 50cm between the alert level and the observed tidal levels, as reported by tide gauges at Plymouth and Weymouth. The Channel Light Vessel reported a wave period of 8s and significant height of 2.7m at 0700 UTC. These data are likely to reflect locally generated wind waves and not the long-period swell component because only one averaged value is reported. Later in the day an 11s wave period was recorded. However, the WaveNet buoy in Poole Bay ( N, W) reported a peak wave period of 12 13s around UTC with direction about 210, and of about 16s around 1300 UTC (Figure 2). This buoy usefully provides multispectral and directional data, thus it is able to separate out the different wave periods. Events of 13 February 1979 The events of 13 February 1979 have been well documented by Draper and Bownass 60 Figure 2. Graphs showing wave height and wave peak period (T peak ) data for four events. Data from the WaveNet buoy in Poole Bay ( N W.).

3 (1982; 1983). From eyewitness testimony, the Axe Yacht Club building, located on the top of the beach at Seaton in Devon, had its roof broken in two and a large amount of shingle was washed onto the seafront road, while some 80 properties were flooded on the seafront and harbour road (East Devon District Council, 2008, p. 16). Events had an impact along the English Channel coast as well: for instance a fishing boat was lifted onto the harbour wall at Lyme Regis. The town of Portland, behind Chesil Beach in Dorset, received serious flooding, and overtopping occurred at Hurst Beach in Christchurch Bay. The cause of these long-period swell waves was considered by Draper and Bownass (1983) to be the effect of trapped fetch conditions acting upon the ocean surface for an extended period. They reported a wave height of 7m and a period of 18s at the Data Buoy 1 at about 48 N, 10 W at 0100 UTC on 13 February. The Wavefinder near Sines, south of Lisbon (Portugal), reported a maximum wave height of 17.2m and period of 20s at around 0340 UTC with a significant wave height of 9.4m. The trapped fetch seems to have first developed south of a low pressure system, first seen south of Newfoundland, with wave heights and periods increasing as the low centre then crossed the Atlantic (Figure 3). However, Lamb and Frydendahl (1991) suggest the large waves were caused by an easterly flow with the gradient speed estimated at 100kn over the eastern English Channel. This wind speed, though, was not evident in surface observations at Portland, where surface speeds were recorded of around 10kn (Gibbs, 1982). The lack of gale force winds along the Channel coast meant that rough seas were not expected. The analysis and evidence presented by Draper and Bownass (1982; 1983) is considered to be the more reliable here. These waves arrived at the time of spring tides, together with a notable surge of 82cm at Newlyn. In Portland Harbour there was a recorded surge of 52cm (Draper and Bownass, 1983). Wave set-up (where water levels pile up near coasts due to the pressure of the waves) may have added a metre to water levels at Chesil Beach, and it is likely that the beach height had been degraded due to previous winter storms. Draper and Bownass (1983) also suggest that refraction of the waves may have been significant in the Portland area. An analysis of Atlantic synoptic charts in mid-february for this event (Figure 3) reveals rapid cyclogenesis to the southeast of Newfoundland. Although the detail is not perfect on these charts due to lack of observations and adequate satellite imagery, the general theme can be picked out. There was a very marked temperature gradient between the cold continental air from North America and the tropical Figure 3. Synoptic analyses from 10 to 13 February Figure 4. Synoptic analyses 31 December 1985 to 2 January English Channel coastal flooding Weather March 2014, Vol. 69, No. 3 61

4 Weather March 2014, Vol. 69, No. 3 English Channel coastal flooding maritime air in the warm sector at 1200 UTC on 10 February: a temperature of 20 C was reported near Prince Edward Island at 47 N, 65 W, with +20 C at a ship at 33 N, 51 W. The low centre dropped rapidly to 956mbar by 1200 UTC on 11 February with its location at 48 N, 38 W. A 60kn mean wind speed was reported by a ship at 42 N, 40 W, indicating the presence of a very strong gradient south of the low pressure system. By 1200 UTC on 12 February the low had moved eastwards to 48 N, 18 W with central pressure around 968mbar. Then 24h later the low centre was located in Lyme Bay in the English Channel. During the strongest storm development period the centre was moving roughly in a straight line relative to the curvature of the Earth, travelling between 29 and 33kn and with a gradient speed on the southern flank estimated at around 60kn (see Table 1). Events of 2 January 1986 Nicholls and Webber (1988) report overtopping of Chesil Beach, and Hurst Beach in Christchurch Bay, on 2 January 1986 due to long-period swell waves running eastwards along the English Channel. At West Bexington, further west along Chesil Beach, a 16s main wave period was identified, with a lower notable period of some 9s. The wave height in Christchurch Bay was manually observed to be near 2m with two wave periods reported, one at 9s and a longer period of 25s (although this larger figure is unverified and appears somewhat unrealistic). These long-period swell waves also occurred with a marked tidal surge of around 1m in the English Channel due to the approaching low pressure centre of 978mbar at 1800 UTC (Nicholls and Webber, 1988). The swell waves developed on the southern flank of a deep area of low pressure that moved at a steady speed across the Atlantic (LP, Figure 4). The central pressure is given at 970mbar at around 50 N, 38 W at 1200 UTC on 31 December A day later it was 960mbar and located around 51 N, 20 W. By 1200 UTC on 2 January the centre was at 52 N, 04 W over west Wales. A secondary low (LO, Figure 4), at 977mbar, developed and approached the western entrance to the English Channel near the Isles of Scilly at 1200 UTC on 2 January, then moved to lie near the Channel Islands 12h later. During the 48h period (1200 UTC 31 December to 1200 UTC 2 January) the primary low centre moved broadly eastwards at an average speed of 28kn with a very strong gradient on the southern flank. pressure centre developed to the south of Newfoundland (not illustrated), then tracked northeastwards, before turning more southwards by 09/0000 UTC (Turton and Fenna, 2008). On this occasion the deep low pressure centre moved eastsoutheastwards towards the west of the UK. The wave period increased to around 15s to the west of Ireland (Turton and Fenna, 2008). Because of the low centre s more northerly track coastal flooding problems were not reported in the English Channel. The buoy in Poole Bay reported a peak wave period increasing to around 17 18s in the early afternoon, continuing until evening with wave heights between 3 and 4m (Figure 2). Events of 10 March 2008 Turton and Fenna (2008) also mention coastal flooding around the southwest of England and south Wales in early March A rapidly deepening low pressure centre moved eastsoutheast from 58 N, 38 W at 09/0600 UTC to 52 N, 10 W 24h later, with surface pressure falling below 950mbar for a time (Figure 5). The speed of movement of this low centre was around 42kn, probably moving ahead of the swell waves. This event led to a significant storm surge of 0.9m at Southampton during a period of spring tides, together with severe gales and locally generated wave action. The tidal level recorded at Southampton was reported to be the highest since measurements started in Coastal flooding was also reported at Sandbanks, near Bournemouth, and at Selsey Bill. At Portland there was significant infiltration and overwashing of Chesil Beach as the lagoon filled up with water, reaching the Ferrybridge car park and nearly flooding the road (Haigh et al., 2011; West, 2012). Much of this may have been due to locally generated storm waves in addition to the storm surge. The Poole Bay buoy indicated wave heights in excess of 5m and wave period increasing to 18 20s later in the day (Figure 2). Longer period swell waves may have been responsible for flooding around the Channel Islands. With the low centre tracking from the westnorthwest it is likely that the main energy of the longer period swell was directed more towards the south of the English Channel. 62 Events of 8 and 9 December 2007 A similar synoptic pattern is observed in the events of 8 and 9 December The low Figure 5. Synoptic analyses 9 10 March 2008.

5 Events of 15 and 16 February 2011 On 15 and 16 February 2011 another notable event occurred following a deepening area of low pressure south of Newfoundland. This low, with central pressure 969mbar, was located at 43 N, 55 W at 0600 UTC on 13 February, and then moved quickly northeast to lie at 51 N, 33 W by 14/0600 UTC with central pressure 954mbar, and 961mbar with a location of 53 N, 25 W at 15/0600 UTC. The low centre moved very rapidly in the first 24h period, then slowed markedly. However, the strong westerly gradient moved forward with the frontal trough, thus producing a long, broadly westerly fetch (Figure 6). The longperiod swell waves generated would therefore seem to be due to a trapped fetch, initially from the moving low pressure centre, then with the westerly gradient. The waves reached the south coast of England on 15 and 16 February, causing problems at several locations. At Chesil Beach the shingle bar became saturated and came very close to flooding the Chiswell area of Portland, just to the rear of the shingle bar. Significant amounts of shingle were removed from beaches further along the south coast at South Hayling Beach and Littlehampton s Climping Beach by the very long-period swell. A photograph shows cliffing and reprofiling of the beach on the morning of 16 February (Figure 7). A long-period swell in excess of 18s was predicted by the Wavewatch-III Spectral 2D model in the English Channel, and observed by the buoy in Poole Bay (Figure 2). English Channel coastal flooding Weather March 2014, Vol. 69, No. 3 Events of 16 and 17 December 2012 The synoptic pattern of the 16 and 17 December also seems to correlate with the development of long-period swell waves, although the trapped fetch is perhaps not so obvious in relation to the speed of the low centre, which initially moves relatively slowly. The low centre at 1200 UTC on 13 December 2012 lies around 55 N, 35 W, and then drifts slowly eastwards to lie at 52 N, 29 W some 48h later at 1200 UTC on 15 December It then moves quickly to lie around 55 N, 13 W by 1200 UTC on 16 December 2012 (Figure 8). However, although the low centre was slow-moving for a time, there is also evidence of a strong west to southwest gradient flow directed towards the UK through the latter period, which may have helped to maintain the swell wave energy. The low centre lies further north than the other events discussed above. It is also noteworthy that south to southeast gales were experienced in the English Channel on the 14 December 2012, with locally generated waves causing beach loss along Lancing seafront and Pagham Beach at Bognor Regis. Figure 6. Synoptic analyses February Figure 7. Beach erosion at Hayling Island on 16 February 2011 (photograph by Ian Bowler). The event of December 2012 also provides an opportunity to examine some of the forecast modelling capability. At 1800 UTC on 16 December (from the Met Office North Atlantic and European Wave model T+66) swell waves were forecast in 63

6 64 Weather March 2014, Vol. 69, No. 3 English Channel coastal flooding Figure 8. Synoptic analyses December Figure 9. Met Office North Atlantic and European wave model for 16 December The short arrows are swell direction, the numbers peak period. The contours represent significant wave height (although mainly the swell component) with the green shading less than 2m, yellow shading 2 4m, amber shading 4 6m, and the red shaded area greater than 6m. Lyme Bay and Poole Bay with a period of 18 20s, and 14 16s along the coast of Sussex and Kent (Figure 9). The Wavewatch-III Spectral output, for a location near Chesil Beach, also shows an interesting pattern with a slight figure 8 shape and wave peaks around 16 18s, and a second peak around 10 12s. The direction is given as towards the northeast ( ). This can be seen on the chart and in tabulated data (Figure 10) for a forecast time T+75 (0300 UTC on 17 December 2012). This figure shows wind direction, swell direction and wave period. This seems to have been well modelled in comparison with observational data from the WaveNet buoy in Poole Bay ( N, W). This indicates wave heights of between 1.5 and 2.5m on December, a maximum period of between 15 and 19s, and a total period of around 6 7s (Figure 11). Discussion Evidence gathered from a number of English Channel events suggests that constraint of the northward progression of the deep low centres is a significant factor. The constrained low centre then moves eastward in roughly a straight line relative to the Earth s curvature, while at the same time maintaining its intensity. The speed of the gradient wind and the speed of the movement of the low pressure system appear to be critical. The low centre for the February 1979 event moved with a speed between 25 and 33kn initially northeastwards, then eastwards with a very strong gradient on the southern flank (see Table 1 and Figure 3). The speed and direction of movement of the low centre then correlate reasonably well with the generated group wave speed assuming a gradient wind speed of 60kn. The events of January 1986 and October 2006 have low centres moving with a small northerly component relative to the curvature of the Earth, and on these occasions the size and period of the induced swell waves were weaker, although still noticeable. However, the situation at 1200 UTC on 2 January 1986 is complicated by the presence of secondary low LO that moved to lie near 49.5 N, 09 W (Figure 4). The main low centres of these two events seem to have had an average speed of 27 28kn: the January 1986 event may have had gradient wind speeds around 50 60kn, but the October 2006 event appears weaker, from observations. The trajectory of the low centres discussed here is shown in Figure 12. The two more recent events in February 2011 and December 2012 also show conditions for the development of long-period swell waves. The February 2011 event saw rapid cyclogenesis to the southeast of Newfoundland, before the depression became slow-moving in the mid-atlantic. However, the frontal trough moved rapidly towards the UK, with corresponding strong west to southwest flow. This event caused some problems along the south coast. The events of December 2012 do not appear to have caused serious problems, although long-period swell waves were identified in models and observations. Local Environment Agency responder teams have pointed out that south to southeast gales in the English Channel on the 14 December led to beach loss, but that effective warnings meant that it was possible to build the beaches up again between high tides and this prevented notable flooding. This is carried out with mechanical equipment in response to warnings of flooding. The events of December 2007 also do not appear to have caused any flooding along the English Channel coast. However, the events of 10 March 2008 led to serious flooding, but the speed of movement of the low centre was around 42kn and probably in advance of the group wave speed. Flooding was mainly due to locally generated storm waves and a storm surge at the time of spring tides, although long-period swell waves may have caused flood damage in the Channel Islands. Another important feature is the characteristic of the beach slope, with events occurring on relatively steep sloping shingle beaches (Nicholls and Webber, 1988). With long-period swell waves the energy of the wave is focused forwards, with the wave not breaking at the base of the beach: thus the directed energy forces water up the relatively steep slope and overtops the beach, with resultant coastal flooding. Where the waves do break at the top of the beach it may also lead to erosion of the shingle (Figure 7). Shorter period waves generally break at the bottom of the beach and dissipate the energy. It is possible that

7 Figure 10. Wavewatch III model 16 December Figure 11. Swell wave observations December Significant wave height, Tz = mean wave period, Tpeak = peak wave period. Summary The presence of long-period swell waves moving along the English Channel coast, formed by travelling North Atlantic storm systems, has historically caused serious problems of coastal flooding, although the more severe events are quite rare. This study highlights seven events that show some similarities. These involve deep, travelling Atlantic depressions with conditions conducive for the development of long-period trapped fetch waves. The worst events seem to occur with rapid cyclogenesis to the southeast of Newfoundland, followed by constraint of the northward progression of the low centre, thus forcing the low centre due east, with the forcing winds moving in a roughly straight line relative to the curvature of the Earth. The generated long-period swell waves then are directed towards the UK. The speed of movement of the low centre for a given gradient wind speed needs to keep track with the group wave speed. The worst events also seem to occur with the low centre moving into the English Channel, which may help to focus and maintain the wave energy as the waves enter shallower water. Other events, for instance on 10 March 2008, have seen rapid cyclogenesis southeast of Greenland with the low centre then moving eastsoutheastwards towards the UK, but the primary cause of coastal flooding was more likely to be locally generated stormy seas and a storm surge during the spring tide. Significant swell waves may also develop in association with strong and long straight gradients across a large area of the North Atlantic. There is ongoing work to try and model these long-period swell wave events, with some success in recent times due to greater model capability and forecaster awareness. This is incorporated in models with the possibility now of picking out the long-period swell waves from the overall wave periodicity. Although on occasions locally generated waves may not be considered sufficiently significant to warrant flood prevention measures, the accurate forecasting of long-period swell waves that are generated at a distance, is seen as increasingly important in order to mitigate the flood risk. A denser network of multispectral wave buoys in the English Channel and southwest approaches would also improve the forecasting capability. English Channel coastal flooding Weather March 2014, Vol. 69, No. 3 Figure 12. Central pressure tracks for events described in the text. The main events described are in black, other events are colour coded as described on the map. degradation of the beach height, due to previous storm activity, may also be a factor in this type of flooding event. In addition, wave set-up may add to water depths near the coast and the more severe events seem to occur near spring tides. Acknowledgements The authors thank Andrew Saulter from the Met Office Ocean Forecasting Research and Development team for comments, and Ian Bowler, from the Environment Agency, for comments and use of his photograph. WaveNet data has been sourced with thanks via the Centre for Environment, Fisheries & Aquaculture Science (Cefas). Thanks are also given to the reviewers who kindly provided useful additional insights. 65

8 Weather March 2014, Vol. 69, No. 3 English Channel coastal flooding References BBC News High Tide Washes away Beach Huts, BBC News Online, Tuesday 24 October 2006, england/devon/ stm (accessed 3 June 2013). Bowyer PJ, MacAfee AW The theory of trapped-fetch waves with tropical cyclones an operational perspective. Weather Forecast. 20: Draper L, Bownass TM Unusual waves on European Coasts, February Proceedings 18th Coastal Engineering Conference, Cape Town. American Society of Civil Engineers: Reston, VA; pp Draper L, Bownass TM Wave devastation behind Chesil Beach. Weather 38: East Devon District Council Strategic Flood Risk Assessment, Level 1, SFRA. Volume 1, Main Report. East Devon District Council/Halcrow Group Ltd: Exeter, UK, September. Gibbs P Observations of short term profile changes on Chesil Beach. Proc. Dorset Nat. Hist. Archeol. Soc. 102 (for 1980): Haigh I, Nicholls R, Wells N Rising sea levels in the English Channel 1900 to Marit. Eng. 164(MA2): Lamb H, Frydendahl K Historic Storms of the North Sea, British Isles and Northwest Europe. Cambridge University Press: Cambridge, UK: 204 pp. (Paperback Re-issue 2005, ISBN paperback). Lapworth A Wind against tide. Weather 66: Nicholls RJ, Webber NB Characteristics of shingle beaches with reference to Christchurch Bay, Proceedings 21st International Coastal Engineering Conference, Torremolinos, Spain. Volume 3. American Society of Civil Engineers: Reston, VA; pp Turton J, Fenna P Observations of extreme wave conditions in the northeast Atlantic during December Weather 63: West IM Chesil Beach: Storms and Floods. Geology of the Wessex Coast of Southern England. School of Ocean and Earth Science, Southampton University, Version: 19th June www. southampton.ac.uk/~imw/chestorm.htm (accessed 3 June 2013). Correspondence to: Andrew Sibley andrew.sibley@metoffice.gov.uk 2014 Crown copyright, the Met Office Weather 2014 Royal Meteorological Society This article is published with the permission of the Controller of HMSO and the Queen s Printer for Scotland. doi: /wea.2145 Ancient Greek drama as an eyewitness of a specific meteorological phenomenon: indication of stability of the Halcyon days 66 Christina Chronopoulou 1 A. Mavrakis 2 1 Theatre on Education, Educational Department of Primary Education, National and Kapodestrian University of Athens, Athens, Greece 2 Department of Economic and Regional Development, Institute of Urban Environment and Human Resources, Panteion University, Athens, Greece Introduction The aim of this paper is to investigate the weather conditions and circumstances under which the audience of the open theatre of Dionysus in Athens would have watched drama in the middle of winter during the Attic month of Gamelion (15 January to 15 February). Since antiquity, during that period of the year there were some days called Halcyon days, characterised by clear, sunny weather conditions. This paper concerns the indications of stable weather conditions for the performance of dramatic festivals during Gamelion, in Athens in the fifth and in fourth centuries BC by studying the ancient Greek drama. We suggest that the dramas of classical years can be used as credible sources of information useful for the study of the climate in Attica during the classical era, as well as with other palaeoclimatological studies. Ancient manuscripts can provide valuable meteorological information to help modern scientists reconstruct the climate of the past. This paper analyses the writings of the dramas of Aeschylus, Sophocles, Euripides and the comedies of Aristophanes during the Golden Age, an era of artistic and literary achievements in Athens from the fifth to fourth century BC. These theatrical texts provide descriptions of clear and stable weather conditions, as seen through the eyes of a simple observer. The lack of sudden weather phenomena and the stability in the appearance of the Halcyon days allowed the dramatic festivities of Lenaia to be performed, during winter time, in an open space: the theatre of Dionysus being located in the southern foothills of the Acropolis in Athens. Reconstructing climate from trees, ice cores and coral provides evidence of past weather, but from human sources scientists are limited by the historical information available. McCormick et al. (2012) have reconstructed climate-change indications during and after the Roman Empire using a combination of scientific and historical data. Also, Domínguez-Castro et al. (2012) analyse the writings of scholars, historians and diarists in Iraq during the Islamic Golden Age between AD 816 and 1009 for evidence of abnormal weather patterns. In addition,