Observed trends in the snow-to-liquid precipitation ratio over Romania

In the regions with temperate climate, solid precipitation usually prevails during the winter time. However, a warming climate could alter the timing of snow accumulation and resulted amounts with major impact on the hydrological cycle. This study analyses the changes in the monthly snow-to-liquid precipitation ratio (SLPR)  over the October-May interval in Romania, based on daily precipitation, air temperature and snow depth data provided by 114 weather stations from the national meteorological monitoring network, over the 1961-2021 period. The observed trends showed a country-wide and significant decline in SLPR. The most notable decline is observed during the late winter and early spring months (February-March), with decreasing trends at over 70% of the weather stations, although only 20% suggest statistically significant changes (p value < 0.05). The autumn months (October and November) depict no statistically trends. The trends observed in the late spring (April and May), show a strong decline in SLPR for most mountain weather stations (above 1,000 m), at rates that could exceed 5% per decade (e.g., Tarcu weather station, 2,200 m, the Southern Carpathians). Evidence of elevation dependency of SLPR trends has been found in spring. The results show that the SLPR declines with altitude, especially in April (R² = .30) and May (R² = .67), when the correlations are statistically significant (p<0.05).

This work was co-funded by the European Social Fund, through Operational Programme Human Capital 2014-2020, project number POCU/993/6/13/153322, project title  “Educational and training support for PhD students and young researchers in preparation for insertion into the labor market”.