Abstract : 3K.15
Snow cover variability and trends in the Tatra mountains in 1921-2006

Milan Lapin, Pavol Fasko, Jozef Pecho
Faculty of Mathematics, Physics and Informatics, Comenius University Bratislava

The Tatra Mountains in Slovakia consist of the High Tatras (2655 m a.s.l.), the Western Tatras (2248 m a.s.l.), the Belianske Tatras (2152 m a.s.l.) and the Low Tatras (2043 m a.s.l.). The Liptovska hollow (west) and the Popradska hollow (northeast) have the bottom altitude from 400 to 900 m a.s.l. Including the valleys and hollows, the all area is about 7000 sq km large. Because of upwind and lee effects the snow conditions are very complex there. Some of the southwestern to northwestern upper slopes have even more than 250 cm of maximum of snow cover depth with very high probability of depths above 50 cm from December to March. In the Popradska hollow (about 700 m a.s.l.) the snow cover occurrence is relatively low also in January and February. Regular observations of daily snow cover, new snow and precipitation totals in this region have started at about 100 stations in 1921 (data from 25 stations are complete up to present). We consider the 85-year series of data as enough long for statistical analysis of variability and trends of basic snow cover characteristics also at areal consideration. Maps of snow characteristics have been designed by use of Arc View GIS software, while some grid data in higher altitudes have been prepared by the regression method. Selected graphs show a sample of trend analysis for 6 stations. The obtained results proved the unequal snow condition trends in the region. The most significant differences were found between the northwestern and southeastern part. It seems that variability and trends in snow cover characteristics are influenced both by air temperature and precipitation variability. This influence depends significantly on the altitude and local topography conditions. Increase of air temperature by about 1.2 C and change of precipitation totals from 10% to +20% in the November-April season are the main reasons of obtained trends. Another reason is connected probably with the change in the atmosphere circulation patterns.