The distribution of the monthly 24-hour maximum amount of precipitation in Romania according to their synoptic causes

Abstract

In the present paper we have analysed the synoptic conditions generating the maximum amount of precipitation within 24 hours in Romania. This study is based on the analysis of daily weather maps from different archived sources and also on the processing of ROCADA data set concerning the daily amount of precipitation in Romania (1961-2013). Some main weather types (WTs) - specific for the occurrence of high amount of precipitation in Romania - were established, and the daily recording of the maximum amount of precipitation for 24 hours at monthly level was assigned to one of the defined WTs. Out of the total of 312 days analysed from the synoptic point of view, a total of 133 days (42.6%) were characterized by high atmospheric instability. The larger part of them (100 days) were determined by cold air advections associated to long-wave troughs propagating from North Atlantic towards the centre of European continent, while the rest of 33 days were generated by cut-off lows identified in the middle and upper troposphere in South-East Europe. As well, 124 days (39.7%) were assigned to Mediterranean cyclones transiting the region of Romania and 55 days (17.7%) were associated with Atlantic cyclones activity. The climatology of each synoptic type is presented. Also, regional and seasonal disparities are described using proper interpolation methods.