CHANGES IN COLD DAYS FREQUENCY IN EXTRA-CARPATHIAN AREAS OF ROMANIA.

The begining of the 21st century has been marked by rising mean temperatures for most stations in Europe. Thus in the north and center of the continent mean temperature values recorded show significant increases in winter (DJF), and in Mediterranean areas there is an increase in summer (JJA), warming of the land surface is manifested in synchronous altitude. In this context this research focuses on detecting and highlighting the changes in the number of cold days (TG 10thpercentile) in the lower troposphere (under 700 hPa), above the extra Carpathians area of Romania. For each selected level, respectively: ground level, 925, 850 and 700 hPa was calculated index frequency and statistical significance of the trend by using nonparametric Mann-Kendall test. The results showed a decrease in variable frequency with regional differences set by particularities of the lower troposphere movements. [ABSTRACT FROM AUTHOR]