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Trendy temperatury powierzchni oceanu w sektorze pacyficznym Oceanu Południowego w ostatnim 25-leciu

Marsz A. A.

Problemy Klimatologii Polarnej

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2005

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nr 15

17-26

PL

Praca omawia zmiany temperatury powierzchni wody (TPO) sektora pacyficznego Oceanu Południowego w pasach szerokości 60 i 50°S, zachodzące w przekrojach miesięcznych i rocznych. Stwierdzono występowanie ujemnych trendów TPO w całym pasie 60°S, z czego ponad 1/3 współczynników trendu jest istotna i wysoce istotna statystycznie. Obszary silnego ochłodzenia powierzchni oceanu tworzą tam dwa ośrodki: pierwszy w rejonie 170°E - 140°W, drugi - 120-080°W. W obu ośrodkach najsilniejsze spadki TPO następują w miesiącach chłodnej pory roku (maj - sierpień), w drugim - dodatkowo - stosunkowo silne ochłodzenie zaznacza się w miesiącach ciepłej pory roku (styczeń - marzec). Na szerokości 50°S ochłodzenie jest znacznie słabsze - istotne statystycznie zmiany TPO zaznaczają się wyłącznie po wschodniej stronie sektora (100-080°W), gdzie również występują trendy ujemne. Kumulacja istotnych i nieistotnych statystycznie trendów miesięcznych prowadzi do zaznaczania się na obszarze około 54% powierzchni sektora pacyficznego Oceanu Południowego istotnych statystycznie, ujemnych trendów rocznej TPO. Na pozostałym obszarze badanego sektora bądź brak realnych zmian TPO, bądź występuje tendencja do słabego spadku temperatury. Przebiegi temperatury rocznej wskazują, że w ośrodku zachodnim (60°S, 170°E -140°W) TPO konsekwentnie obniża się od początku obserwacji (1980 rok), gdy we wschodniej części sektora pacy-ficznego (120-080°W) cały obserwowany w 25-leciu trend stanowi konsekwencję silnego spadku rocznej TPO w ciągu ostatnich 7 lat (1997-2004).

EN

This work deals with monthly and annual changes in sea surface temperature (SST) of the Pacific sector of the South Ocean observed in 60°- 50°S latitudinal bands. The occurrence of negative trends of SST was noted in the entire 60° band and 1/3 of the trend coefficients is statistically significant and highly significant. The regions marked by strong cooling of ocean surface are formed by two centres - one 170° - 140°W and the other extending from 120° to 080°W. The greatest decrease in sea surface temperature in both centres takes place during cold season (May - August), in the other centre there is also additional quite strong cooling in the months of warm season (January - March). In the latitude 50°S the cooling is much weaker - statistically significant changes in SST are observed only in the eastern part of the Pacific region (100°- 080°W) where negative trends are also noted. Cumulating of statistically significant and non-significant monthly trends leads to statistically significant negative trends in annual SST observed in 54% of the area in the Pacific sector of the South Ocean. In the remaining area of the Pacific sector of the South Ocean there are either no visible changes in the sea surface temperature or there is tendency of weak decrease in temperature. The courses of annual SST indicate that in the western region (60S°, 170° -140°W) the SST has been decreasing constantly since the beginning of the observational period (since the year 1980), whereas in the eastern part of the Pacific sector (120°- 080°W) the whole trend observed over the 25-year period results from strong decrease in annual SST in the period of last 7 years (1997-2004).

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Stan termiczny Atlantyku Północnego a zlodzenie mórz Barentsa i Grenlandzkiego (1972-1994)

Styszyńska A.

Problemy Klimatologii Polarnej

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2004

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nr 14

39-57

EN

This work deals with correlations between anomalies in SST (sea surface temperature) in the North Atlantic and the sea ice area of the Barents and Greenland seas. This research made use of mean monthly sea ice cover with density >= 10% observed in the Barents and Greenland seas over the period 1972-1994 (calculated on the bases of weekly area of sea ice cover of the above mentioned seas collected in NCDC data set ?1972-1994 Sea Ice Historical Data Set?). The thermal condition of the North Atlantic is characterised by the values of anomalies in mean monthly sea surface temperature (SST) in so called ?controlled grids? (2° x 2°) selected/appointed here by A.A.Marsz (1999a, 2001). Their location is presented in Fig.1. A standard statistical analysis has been used in this research (correlation analysis, regression analysis). The strongest synchronic correlations (observed in the same months) with the sea ice cover of the said seas have been noted in grids located north of the North Atlantic Current and characterising the following waters (Tables 1 and 2): of the Labrador Sea (located within the range of Labrador Current activity) - [50,52], those north of the Gulfstream delta - [40,52] and those located inside the circle of the cyclonic circulation of the North Atlantic - [30,54]. The highest coefficient values of linear correlation, at a level p<0.05 exceeding the statistical significance, were noted in winter months (December, January, February) and those spring ones (April, May, June) as well as in summer - in July and August (the Greenland Sea). There are also several asynchronic correlations. The results of analysis of multiple regression between the SST anomalies and the area of the sea ice cover indicated that the sea areas in which the changeability in their thermal condition has the greatest influence on the formation of the sea ice cover of the said seas are located in the western part of the North Atlantic.

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Wpływ zmian temperatury powierzchni oceanu na Morzu Norweskim na temperaturę powietrza na Svalbardzie i Jan Mayen (1982-2002)

Kruszewski G., Marsz A. A., Zblewski S.

Problemy Klimatologii Polarnej

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2003

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nr 13

59-78

EN

This work deals with correlations between SST in the Norwegian Sea and air temperature at selected stations located in the Atlantic sector of Arctic (Bjornoya, Hornsund, Svalbard-Lufthavn, Ny Alesund and Jan Mayen). The southern and central parts of the Norwegian Sea show the strongest correlation with the air temperature at the above mentioned stations, whereas the northern parts of this sea show weaker correlation. Apart from synchronic correlations (occurring in the same months) asynchronic correlations have been found. The latter are generally much stronger than the synchronic ones. The predominant influence on the changes in air temperature at the stations have the winter SST (JFMA) in the central part of the Norwegian Sea (grid 2° x 2°, 67°N, 010°E). These winter SST show quite strong correlations with monthly air temperature at Bjornoya, Hornsund, Svalbard-Lufthavn and Jan Mayen in July, August and September. At Ny Alesund station the period with statistically significant correlation between the air temperature and the winter SST is limited to September. The strongest correlation can be observed in August (see Table 4). The observed correlations result from modification in atmospheric circulation, caused by increased heat volume in the Norwegian Sea. Such modification is reflected in the increased frequency of occurrence of meridional atmospheric circulation, which is accompanied by the increase in the frequency of air advection from the S to this sector of Arctica. Some correlations which show more significant time shift have also been observed (see Table 5). Winter SST indicate positive correlations with air temperature observed at Bjornoya and Horn-sund in August and September the following year and at Svalbard-Lufthavn in September. At Ny Alesund station the coefficients of correlation with the air temperature in the following year are increased but they do not reach the statistically significant level. Another period with statistically significant correlations is November and December the following year; significant correlations with winter SST occur at Bjornoya (r = 0.71) and all stations located on Spitsbergen (r = 0.57). The correlations of SST with air temperature observed at Jan Mayen the following year are different, i.e. the presence of strong correlations is limited to summer season - July, August and September (r ~ 0.6). The correlations with winter SST occurring in November and December the following year is connected with warm masses carried to this region together with waters with the West Spitsbergen Current. Correlations between SST and air temperature present in summer and at the end of summer the following year may probably be influenced by the modification of atmospheric circulation. The only significant correlation with summer (July and August) SST indicates the temperature of February the following year at stations located on Spitsbergen and Jan Mayen. These correlations are negative (r ~ -0.55 - -0.50). The reason for occurrence of such correlations is not clear. The changeability of winter SST in the central part of the Norwegian Sea explains from 20% (Hornsund) to 32% (Bjornoya) of changeability in annual air temperature at the above mentioned stations in the same year and from 34% (Jan Mayen) to 41% (Hornsund) of changeability in annual air temperature in the following year. The increased level of explanation of changeability in air temperature the following year influenced by winter SST is connected with the delayed flowing of the Atlantic waters to high latitudes carried with the Norwegian Current and the West Spitsbergen Current.