Some mechanisms of abnormal surface air temperature formation in the area of the Spitsbergen archipelago in summer

Abstract

The temperature in the Arctic is increasing faster than the global average. A question that challenges scientific community is whether the intensity and frequency of dangerous meteorological phenomena in the Arctic are increasing as rapidly. The article presents the results of examining abnormal summer seasons in the area of the Spitsbergen archipelago. The study used data on surface air temperature in Barentsburg obtained from 1912 to 2023. The regional average results showed a statistically significant linear summer trend. The mean summer temperature in Barentsburg is increasing at a rate of 0.2 °C/10 years. Positive and negative extremes of seasonal mean temperature in the summer from June to September were determined as higher than or equal to 1,5 standard deviation. The atmospheric circulation at the sea level pressure and at the height of the geopotential surface of 500 hPa is analyzed, and the localization of surface temperatures anomalies for highlighted abnormal temperature in summer season events is discussed. The results of the analysis of atmospheric circulation revealed significant differences between abnormal warm and cold summer seasons. During abnormally cold summers the circumpolar vortex is located in the polar region and causes the advection of cold air masses from the north of Greenland. In the case of abnormally warm summers the cyclonic vortex is shifted to the Canadian Arctic archipelago and the Baffin Sea, while warm air masses from the Atlantic Ocean enter the area of the Spitsbergen archipelago. The assessment of the statistical significance of the correlation between the time series of surface air temperature anomalies and the atmospheric circulation indices Arctic Oscillation, Arctic dipole, Pacific North American oscillation showed significant results in September with the Arctic Oscillation index, in August and September with the Arctic dipole index, in July with the Pacific North American oscillation index. The greatest statistically significant association of surface air temperature anomalies was found with the Arctic dipole index, the closeness of the connection in September was –0.49. Spectral analysis was carried out and the main periods of atmospheric indices fluctuations from 2–3 years to 25 years were determined.