Spitsbergen has experienced some of the most severe temperature changes in the Arctic during the last three decades. This study relates the recent warming to variations in large‐scale atmospheric circulation (AC), air mass characteristics, and sea ice concentration (SIC), both regionally around Spitsbergen and locally in three fjords. We find substantial warming for all AC patterns for all seasons, with greatest temperature increase in winter. A major part of the warming can be attributed to changes in air mass characteristics associated with situations of both cyclonic and anticyclonic air advection from north and east and situations with a nonadvectional anticyclonic ridge. In total, six specific AC types (out of 21), which occur on average 41% of days in a year, contribute approximately 80% of the recent warming. The relationship between the land‐based surface air temperature (SAT) and local and regional SIC was highly significant, particularly for the most contributing AC types. The high correlation between SAT and SIC for air masses from east and north of Spitsbergen suggests that a major part of the atmospheric warming observed in Spitsbergen is driven by heat exchange from the larger open water area in the Barents Sea and region north of Spitsbergen. Finally, our results show that changes in frequencies of AC play a minor role to the total recent surface warming. Thus, the strong warming in Spitsbergen in the latest decades is not driven by increased frequencies of “warm” AC types but rather from sea ice decline, higher sea surface temperatures, and a general background warming.

The study investigated spatial and temporal variability of extreme precipitation trend magnitudes and their directions. Daily precipitation from 48 synoptic stations in Poland for the period 1951‐2006 were used. Five indices of precipitation extremes were chosen: the highest 5‐day precipitation total, precipitation total from events ≥90^th and 95^th percentiles as well as number of days with precipitation ≥ 90^th and 95^th percentiles of daily precipitation amount. Trends in extreme precipitation indicators were analysed over semi‐annual periods as well as over the standard climatological seasons. Trends were calculated for each of the 30‐year moving periods within 1951‐2006 using a simple linear regression method. Their significance was tested with the Mann‐Kendall method.Decreasing trends in extreme precipitation indices dominated in both the warm and cool halves of the year and in the seasons. The greatest change was recorded in the least extreme precipitation indices. Summer was the season with the greatest number of statistically significant trends, mostly decreasing ones. Upward trends, having the greatest spatial extend in autumn, dominated the initial 30‐year periods of the study period whereas the decreasing trends were common in the 30‐years from 1956. In summer and winter, decreasing trends reached the greatest degrees of stability in southern Poland. In spring and autumn, a stable fall of extreme precipitation indices was mainly recorded in the south‐western part of the country. Stable increasing trends were recorded sporadically. However, in spring trends towards an increase were more frequent than in other seasons. The strongest decreasing trends were observed in summer and winter, mainly in the south, while in autumn they also occurred in the west. Copyright © 2009 Royal Meteorological Society

Spatial and temporal trend variability in extreme precipitation indices was studied for the meteorological seasons from 1951 to 2006. Eight indices were used, describing their frequency (90pNoD, 95pNoD), totals (1dayT, 5dayT, 90pT, 95pT) and intensity (90pInt, 95pInt). The following key challenges were addressed: (1) temporal variability in the relative number of stations with significant 30‐year trends, (2) temporal stability and (3) average magnitude of the calculated 30‐year trends. Temporal changes in the spatial extent of statistically significant extreme precipitation trends proceeded differently in each season. The trend direction, indicated by trend stability analysis, was consistent with that of averaged 30‐year trend magnitudes at most stations. A distinct spatial differentiation emerged in the prevailing trend directions between the eastern and the western part of the study area. In all seasons, increasing trends in extreme precipitation dominated in central‐eastern Germany, whereas opposite trends prevailed in southern Poland. This pattern was particularly prominent in winter. Similarities in the temporal variability of the percentage of significant trends between the eastern and the western sub‐regions emerged in autumn only. Summer was characterized by the most pronounced temporal changes in the percentage of significant negative trends. Summer also showed the most stable extreme precipitation trends of all seasons and a higher trend magnitude than the transitional seasons. Spatial patterns of trend directions in spring, showing the most complex pattern of all seasons, vary depending on the index, particularly with respect to trend stability. Copyright © 2010 Royal Meteorological Society

This contribution provides the basics of the climatology of the Polish Tatra Mountains in a nutshell, with particular reference to intense precipitation and its relation to atmospheric circulation. Variability of various precipitation characteristics, including selected indices of intense precipitation in Zakopane and at Kasprowy Wierch, is illustrated in this paper. None of the trends in these characteristics and indices calculated for the entire time interval exhibit a statistical significance, but short-time fluctuations are evident. The occurrence of intense precipitation in the Tatra Mountains is strongly related to three circulation types. These situations (Nc, NEc, Bc) are associated with cyclones following track Vb after van Bebber. In addition to changing frequencies of circulation, this study also reveals an increase in the frequency of the circulation types associated with extreme precipitation.