| Abstract [eng] |
The aim of this study was the mapping of heavy precipitation in Lithuania and linking it to characteristic meteorological conditions. The research object - spatial patterns of heavy rainfall field during warm part of the year (May-September) of 2011-2018 years. Heavy rainfall episodes – are daily precipitation cases with precipitation rate exceeding 30 mm per day at at least in one Lithuanian meteorological station. It was defined that daily (24-hour period) precipitation episode begins at 6 AM UTC in one day and ends in the second day at the same time - 6 UTC. The main area for analysis – Lithuanian territory. A total number of 31 episodes of heavy rainfall were examined. Primary precipitation rate data were obtained from the Lithuanian Hydrometeorological Service. In addition, daily precipitation data of three different reanalyses, MESCAN-SURFEX, ERA5-land and ERA5 were obtained from the Copernicus Climate Change Service. Further, the Hess – Brezowsky atmospheric circulation classification was used to identify the main large-scale circulation patterns during analysed episodes. The surface analysis of the synoptic conditions during the episodes was done using KNMI Weather map archive, DWD surface analysis archive and UK Met Office Surface pressure charts archive. The maximal total column water vapour, kg m-2, patterns were analysed to determine the moist air advection conditions. The most suitable reanalysis for heavy rainfall analysis appeared to be MESCAN-SURFEX. Most frequent patterns of heavy precipitation located over Ukmergė, Širvintos and Molėtai municipality areas. The synoptic analysis of all episodes shows that heavy precipitation most often in Lithuania is associated with: i) cold front (13 episodes), ii) occlusion front (8), iii) warm front (8), and iv) warm and cold fronts together with the narrow area of the warm sector (2). The moist air responsible for heavy precipitation in Lithuania mostly has been transported from the south (11 episodes), southwest and southeast (6 episodes each). 14 out of 30 Grosswetterlagen (GWL) circulation types accompanying heavy precipitations episodes were defined. Most frequent of them appears to be WZ, NWA, TRM, SWZ and TM. |
