Regional and seasonal inhomogeneity of climatic variability in the Far-Eastern Seas Elena I. Ustinova, Yury D. Sorokin and Svetlana Yu. Glebova Pacific Fisheries Research Centre (TINRO-Centre) 699 Shevchenko Alley, 4, Vladivostok, Russia E-mail: eustinova@mail.ru PICES- (POC-P-786) This presentation summarizes our studies on inhomogeneity of climatic variability in the Japan/East, Okhotsk and Bering Seas. We estimated the regional and seasonal features of climatic variability.
We used historical and contemporary sources of regional data of the observations on various thermal and atmospheric circulation parameters State of atmosphere: thermal (air temperature) and dynamic (SLP, trajectories of cyclones, Kunicin s index, types of regional atmospheric circulation, etc) Thermal parameters in the Seas: long time series: ice cover (regular ten-days aircraft observations conducted by Russian Hydrometeorological Service and satellite information) SST (Time series of the -day mean SST from 9 to latest month for degree square of the Northwestern Pacific from the Real Time Data Base, NEAR-GOOS, http://goos.kishou.go.jp/rrtdb) T and S by oceanographic expedition researches
SST in the selected sub-regions of the Far-Eastern Seas (-7) Summer Spring.5.5 -.5 - -.5 Bering Берингово Sea море - 9 9 97 98 99 3 4 5.5.5 -.5 - -.5 Okhotsk Охотское Sea море - 9 9 97 98 99 6 7.5.5 -.5 - -.5 Japan/East Японское Sea море - 9 9 97 98 99.5.5.5 -.5 - -.5 - -.5.5.5.5 -.5 - -.5 - -.5.5.5.5 -.5 - -.5 - -.5 3 4 5 Охотское море Okhotsk Sea 9 9 97 98 99 6 7 Bering Sea Берингово море 9 9 97 98 99 Japan/East Японское Sea море 9 9 97 98 99
Interannual variability of ten-day ice coverage anomalies in the Far-Eastern Seas Time series are standardized. 5 5 995 99 985 98 975 3.5 3.5.5.5 -.5 - -.5 - -.5-3 -3.5 995 99 985 98 975 97 965 9 3.5.5.5 -.5 - -.5 - -.5-3 97 965 9 December January February March April 5 5 number of ten-day from the beginning of the year Ice conditions
Mean winter (January April) - A, B, C and annual maximum ice cover (in March) D (), mean multi-year value (), long-term contributions (3) and linear trend. S is % to the total area of the Sea S% 45 35 Bering Sea 9- A S% 55 45 C Tatar Strait 9-3 trend 35 5 5 3 trend R =. 955 965 975 985 995 5 5 5 R =.7 5 955 965 975 985 995 5 5 S% 9 8 7 Okhotsk Sea 957- S% Okhotsk Sea B 9 March 99- D 8 7 3 trend y = -.4x + 897.7 R =.9 9 9 97 98 99 trend y = -.38x + 345.47 R =.7 95 935 945 955 965 975 985 995 5 5
REGIONAL THERMAL CONDITIONS IN THE FAR-EASTERN SEAS S% 8 ice cover ten-day Okhotsk Sea 9 9 97 98 99 S% ice cover ten-day Bering Sea ten-day - AAA 9 9 97 98 99 8 6 4 8 6 4 ten-day 8 6 4 8 6 4 S% 9 Annual maximum ice cover (% to the total area of the Sea) and its terms (number of ten-day from the beginning of the year) Tatar Strait 8 6 7 4 8 6 ice cover 4 ten-day AAA - 9 9 97 98 99 ten-day 8
-year running correlation of the mean winter ice extents in the Okhotsk and Bering Sea. R 95%.5 9 97 98 99 -.5 - The ice cover fluctuations show a remarkable feature: their phases are opposite between the Okhotsk and Bering Seas (Yakunin, 966; Khen, 997; Plotnikov, 997; ). However, after the long period of anti-phase variability, the ice cover in these seas began to fluctuate synchronously since late 98s. Recently, ice extent is decreasing in the Okhotsk and Japan/East Seas: the last severe winter was there in -, and the ice extent is low during the last 7 years. Recent changes of ice cover in the Bering Sea have positive tendency, and its year-to-year variations are opposite to the Okhotsk Sea again.
Year-to-year variation of mean winter (January-April) ice cover in the Bering Sea (red) and mean winter temperature in St. Paul (black) 8 6 4 - -4-6 45 35 5 5 5-8 9 9 97 98 99
Winter North Hemispheric temperature anomalies, annual maximal ice cover in the Okhotsk Sea and its polynomial trends 9 8 7 R =.6 8 R =.66 Ice cover Ta NH 95 935 945 955 965 975 985 995 5 - - -
SUMMARY FOR AIR TEMPERATURE Consistent estimations of regional climatic tendencies of air temperature are received by many authors by observations of Russian meteorological stations (Varlamov еt al., 998; Ponomarev еt al.,,, 5, 7; Assessment Report.., 8). Principal features of air temperature climatic tendencies are the following: - strong irregularity and inhomogeneity in time and space connected with specific macrocirculating atmospheric processes on the boundary between Eurasian continent and the Pacific Ocean; - maximal trends to warming in winter and spring in the southern part of the region (Primorye, Japan, southern Kamchatka) and in spring, summer and autumn over Chukotka; - weak negative trends in the areas to the north from the Okhotsk Sea and to the west from the Bering Sea in winter; - tendency to decreasing of the difference between summer and winter air temperatures at the Japan/East Sea and its increases at the northwestern Okhotsk Sea; i.e. the continentality increases in the northern part of Far East and decreases in its southern part.
Air temperature changes in Russia to middle XXI century (4 ), CMIP3 А (left) and observed trends (right) (Assessment Report, 8) Winter Summer Winter Summer Recent Russian studies (Kattsov et al., 7; Meleshko et al., 8; Assessment Report, 8; Gruza and Ran'kova, 9) show the difficulty in realistic simulating regional features of climate in Far East of Russia by atmosphere-ocean circulation models (AOGCMs) presented in IPCC, 7. By models ensemble, the trends of air temperature are positive over the whole Far East region in all seasons, with maximal inclination in its northern part in winter. On the contrary, observed trends to winter warming are the strongest in southern part of the region, but weak negative trends are observed over North-East Asia in winter, and strong positive trends in this area are observed in spring and autumn. These differences between modelled and observed climate changes are obviously caused by processes of regional scale and should be analyzed by regional models of high resolution.
Н 7 8 9 n number of isobars N Kunicin s Index n=5 N=5 7 8 9 6 3 3 5 4 7 9 5 8 7 8 8 4 3 8 6 3 8 9 3 9 36 36 6 9 3 45 9-65 N, E- W General Kunicin s Index (Σ N) is measure of cyclonic intensity 5 5 45 69 4 6 49 44 69 5 57 65 73 Σ N = =997 9 36 7 8 9
Zones of high cyclonic intensity by Kunicin s Index in winter 7 8 9 997 7 8 9 7 8 9 9 7 Зональный индексindex Каца Zonal Katz s -. 3 7 4 998 995 99 989 7 986 983 98 Wind transport over the Okhotsk Sea in winter 6 977 974 996 -.4 8 -.6 7 8 9 998 7 8 9 3 3 7 7 8 8 9 9-8 -.8 -. -.4 9 9 999 7 8 9 4 7 8 9 -.5 -.7 9 -.9-3. -3.3-3.5 7 7 8 8 9 9 7 8 9 5 7 8 9 by Glebova, 7 8 9 7 8 9 7 8 9 8 8 7 7 7 4 998 995 99 Меридиональный индекс Каца Meridional Katz s Index 989 986 983 98 977 974
Number of cyclones Asian-Pacific region Okhotsk Sea Kunicin c Index Asian-Pacific region Okhotsk Sea Winter cyclonic activity (number of cyclones and cyclonic intensity by Kunicin s Index) over the Asian-Pacific region and the Okhotsk Sea Local index Ice Ice Total index Local (over the Okhotsk Sea) and Total (over the Asian-Pacific region) indices (February) vs. Ice and SST in the Okhotsk Sea (March) Index Local index Index SST Ice SST SST Ice Total index SST Index Index
Running correlation with -years period between winter SST in the north (left) and south (right) parts of the Japan/East Sea and large-scale climatic indices.8 Wpw.6.4. -.9 9 97 98 99 -.4 -.6 -.8 -.8.6.4. -.9 9 97 98 99 -.4 -.6 -.8.8.6.4. -.4 AO MEI_ENSO -. 9 9 97 98 99.8 WPw.6.4. -.9 9 97 98 99 -.4 -.6 -.8 -.8.6.4. -.9 9 97 98 99 -.4 -.6 -.8.8.6.4. -.4 -.6 AO MEI_ENSO -.9 9 97 98 99 In a number of cases spatial boundary between distinct types of the relationships is the Polar front in the Japan/East Sea.
SUMMARY Among the Far-Eastern Seas, the most significant reduction of the mean winter ice extent occurred in the Okhotsk Sea, while in the Bering Sea and Tatar Strait a negative trend in ice cover was not statistically significant. Over the past 55 years (957 ), the mean winter value of ice cover in the Okhotsk Sea has decreased by 4% per decade. In the last 5 years, the redistribution of quasi-periodical components contributing to the total variance of ice cover has occurred in the Far-Eastern Seas: the relative contribution of shorter components (with time-scale years) had increased. However, in the areas to the north from the Okhotsk Sea and in Chukotka, weak negative (or insignificant) winter trends of air temperature are observed, while maximal warming in winter and spring occurs over the southern part of the Russian Far East and over the coast of Japan. Recent estimates confirm the tendency of decreasing differences between summer and winter air temperatures over the Japan/East Sea and increasing differences in the northwestern Okhotsk Sea; i.e. the continentality increases in the northern part of Far East and decreases in its southern part. Integrated impacts of cyclones on the thermal variability depends on spatial scales of the atmospheric processes. In a number of cases spatial boundary between distinct types of the relationships between large-scale climatic indices and regional thermal characteristics is the Polar front in the Japan/East Sea. The longest periods of relatively stable linkages were found for winter SST in the subtropical region of the Japan/East Sea with SOI and WP.