Snow cover in eastern Europe in relation to temperature, precipitation and circulation

The basic characteristics of snow cover occurrence in eastern Europe are described. For each month from October to May the range of 'active' snow-cover areas in Europe was determined. The boundary criterion for 'active' regions was adopted as snow-cover probability of between 10 and 90%. The correlation coefficients between the snow-cover characteristics (number of days with snow cover and its monthly mean depth) and other climatic variables (temperature and precipitation) were calculated. A strong positive correlation between the annual number of days with snow cover and the annual number of days with mean temperature <0degreesC was discovered for most parts of the study area. A negative correlation between the monthly number of days with snow cover and monthly mean temperature was found and its spatial distribution was analysed. A positive correlation between snow depth and precipitation appeared significant only in some areas. The influence of atmospheric circulation, expressed by North Atlantic oscillation (NAO) index values, on snow cover in the particular months was analysed. The correlation between the number of days with snow cover and the NAO index is large and statistically significant only in central Europe and it becomes insignificant to the east of 30degrees lambda E. High values are noted only in the winter months. In autumn and spring, when the range of the 'active' areas moves to the east and the NAO becomes weak, the correlation is very small. Copyright (C) 2004 Royal Meteorological Society.