SOME CHARACTERISTICS OF MAXIMUM ANNUAL AND SEASONAL QUANTITIES OF RAINFALL REGISTERED IN 24 HOURS IN ROMANIA.

The paper analyzes some characteristics of annual and seasonal amounts of rainfall recorded in 24 hours in Romania. Annual and seasonal frequency distribution of rainfall quantities registered in 24 hours, air circulation type regarding these events, and the return periods of the absolute maximum values have been analyzed. Annual and seasonal values of maximum 24-hour precipitation amount from 23 weather stations from Romania, located between 3 and 661 m, have been considered over a period of 55 years (1961-2015). First, the data sets were tested using homogeneity distribution test at 99 % of significance level provided by XLSTAT software. HYFRAN software and HYSPLIT model have been employed in order to calculate statistics based on frequency analysis and to identify the atmospheric circulation type, respectively. The main findings are: absolute maximum annual rainfall quantities vary between 65.3 and 224.0 mm, with the highest values (over 120 mm) in the east and south-east part of the country; most of the weather stations have the highest annual frequency between 25- 50 mm, while winter, spring, and autumn are characterized by high frequency of 0-25 mm amounts; for the winter season, the maximum 24-hour precipitation has never exceeded 75 mm, in spring and autumn they are under the 125 mm threshold, while in summer locally exceeded 200 mm; the return periods of maximum annual quantities of rainfall are generally ranging between 32.2 and 387 years, highlighting the continental climate of some regions of the country; four types of air circulation have been detected, more frequent from south and southwest part of the Europe, bringing warm and moist air masses. [ABSTRACT FROM AUTHOR]