Snow variability in Romania in connection to large-scale atmospheric circulation



Daily measurements of snow depth, cumulated precipitation and mean temperature from 105 meteorological stations with continuous record over the 1961–2010 period were analysed for trends with the Mann–Kendall nonparametric test. Trends in the number of days with snow cover, and in the mean snow depth are decreasing at 29 and 18% of the stations, respectively. The decrease in snow depth affects the intra-Carpathian region and Northeastern Romania. The most dramatic change concerns the number of snowfall days, which is decreasing at 82% of the locations. There is a slight decrease in precipitation amount, significant at only 8% of the stations. The mean temperature is increasing at 47% of the stations, while the number of days with temperature over 0 °C shows upward trends at 63% of the stations. Overall, the winter season in Romania has changed substantially. All snow-related parameters show significant negative correlations with the North Atlantic Oscillation (NAO) index for winter. The NAO has a strong impact throughout the country suggesting that the winter variability in Romania is driven by the large-scale circulation over the North Atlantic. Copyright © 2013 Royal Meteorological Society