Zmiany temperatury wody na Prądzie Zachodniogrenlandzkim w okresie 1982-2003

This work deals with the changes in sea surface temperature (SST) in selected grids located along the West Greenland Current (Fig. 1). The West Greenland Current is a warm current, which transports warm waters to the bay/ gulf of the Baffin Sea and in this way has a great influence on the formation of ice cover and on air temperature in this area. The Reynolds's data set, version SST OI v.1., covering values of mean monthly SST in grids 1ox1o has been used as the data source. Yearly temperatures for selected grids have been calculated on the basis of mean monthly temperatures. The Reynolds's data set covers whole years from the period 1982-2002 (21years). This period is especially interesting because during these years (and also at present) an advanced process of sea ice cover degradation and an increase in air temperature has been observed in Arctic. At Greenland, especially during the past few years, an advanced process of ice melting on land was noted - summer ablation reaches the level of 1600-2000m. That is why changes in SST at the same time may also be interesting. Trends in chronological series of mean yearly values of SST in grids located along the West Greenland Current ([59°N, 44°W], [62°N, 52°W], [66°N, 56°W], [70°N, 58°W], [74°N, 60°W] and [76°N, 72°W] ) have been analysed. Such an analysis indicated that in all grids of the West Greenland Current the trends in water temperature prove to be positive and that these trends are statistically relevant (p < 0.05 ) in nearly all grids. An exception to this pattern is the sea area extending around the Cape Farewell (grid [59, 44] - the first part of the West Greenland Current} where the trends are very low and statistically not relevant (Tab. 1). The highest values of trends can be observed in grids [62, 52] (+0.059deg./year) and [74, 60] (+0.051deg./year) resulting in the increase in SST by 1.24°C and 1.07°C over the period of 21 years. These grids are located in the initial and final parts of the West Greenland Current. Far weaker trends were observed in central part of the current [70, 58] - +0.030deg./year and in grid [76, 72] - +0.035 deg/year. Yearly temperatures of water in the West Greenland Current prove to show strong correlation (see Fig. 2). The mean monthly values of SST have also been analysed. The highest values of trends (statistically relevant) were noted in grid [74, 60] in August (+0.193deg/year) and in September (+0.136deg/year) thus giving in the analysed period the increase in SST by 4.05°C and 2.86°C. Such distribution of trends in time indicates that the role of the summer warming of the sea surface has increased. Positive trends in spring and autumn months in grids [62, 52] and [66, 56] are statistically relevant. In grid [70, 58] positive trends are observed both in summer months as well as in winter ones and in the northernmost located grids positive and statistically relevant trends are observed in almost all months during which waters are ice free. Yearly values of SST in the south part of the West Greenland Current prove to show strong negative correlation with the Hurrell NAO index (r~ -0.7; see Fig. 4) the monthly values of SST show delayed correlation with the Hurrell NAO index; correlations which are statistically relevant were noted in the period from June to December, the maximum (r = -0.64 to ?0.74) in the period from August to October. Monthly and yearly values of SST which show statistically relevant correlation with the Hurrell NAO index disappear at latitude 67°N-68°N. In the analysed period the NAO index indicates weak negative trend which is not relevant (-0.052/year), however correlation of yearly SST with NAO index over the analysed period are statistically relevant, e.g. in grid 66°N, 056°W, they explain 45% of the observed changeability in SST (R = 0.69, F(1.19) = 17.6, p< 0.0005).