Sniego dangos režimas Lietuvoje

• Main Authors: Gečaitė, Indrė, Rimkus, Egidijus
• Format: Article in Journal/Newspaper
• Language: Lithuanian; English
• Published: 2010
• Subjects: snow cover duration; maximal snow depth; arctic oscillation; North Atlantic oscillation; Arctic; Kendall; North Atlantic
• Online Access: http://vu.lvb.lt/VU:ELABAPDB4313594&prefLang=en_US

An analysis of snow cover parameters in Lithuania in 1961-2010 is presented. Their spatial distribution, changes in the study period, as well as their relationship with air temperature and precipitation were determined. The statistical significance of the observed trends was examined using the Mann-Kendall test. Relationship between snow cover parameters and large-scale atmospheric circulation patterns over the North Atlantic were also investigated. Data of 18 Lithuanian meteorological stations for the period 1961-2010 were used. The mean annual snow cover duration in 1981-2010 in Lithuania was 82 days (Fig. 1). The spatial mean of the maximum snow depth was 18 centimeters (Fig. 3). The distribution of snow cover indices had very clear meridional features, with some disturbances around highlands. The highest values of both snow cover parameters were determined in the Žemaičiai Highland as well as in Eastern Lithuania. Western Lithuania can be characterized as having the largest annual variation of snow cover indices. A correlation between air temperature and snow cover parameters was negative and statistically significant in the whole Lithuanian territory. The relationship of the air temperature with snow cover duration was closer than with the maximum snow depth. The correlation between snow cover indices and precipitation was weaker. Larger amounts and more often a liquid state of precipitation are typical of warmer winters and explain the negative sign of the correlation. The mean snow cover duration decreased by 17 days during the study period, whereas the maximal snow depth lowered by 3.5 cm (Figs. 2 and 4). The largest negative changes of snow cover duration were identified in Laukuva, meanwhile the most significant decrease of maximal snow depth was observed in Vilnius and Raseiniai. Only in the most eastern part of Lithuania (Dūkštas MS) the tendencies of snow cover indices were positive. A strong negative correlation between large-scale circulation in the North Atlantic and snow cover patterns in Lithuania was identified. During the positive phase of the Arctic oscillation (AO) and the North Atlantic Oscillation (NAO), shorter snow cover duration and a thicker snow cover were observed. The sign of anomalies of snow cover indices and AO values was opposite during 83 of the investigated winters. Smaller spatial differences in snow cover duration in the Lithuanian territory were determined during phases of strong negative oscillations.