Scholarly record

ANALYSIS OF VARIABILITY AND SEASONAL CLASSIFICATION OF EXTREME LARGE-SCALE PRECIPITATION EVENTS IN BULGARIA

Lilia Bocheva

Abstract

The frequency of extreme meteorological and climatic phenomena in Bulgaria has increased in recent years. Especially since the mid-1990s, a series of disaster meteorological situations have caused serious material damages and human casualties in many regions of Bulgaria. Annual precipitation amounts have increased during the last 10-15 years, mainly due to the contribution of heavy rainfall events. The main objective of present study is seasonal analysis and synoptic classification of extreme precipitation events affecting large areas of the country. Examined period is 1991-2017 with precipitation totals (?60 mm/24 h), measured in meteorological network of the National Institute of Meteorology and Hydrology. We are taking into account all heavy precipitations, which are detected in the same synoptic process in at least 4 Bulgarian districts. The classification of synoptic situations, which are divided in different synoptic circulation types, taking into account pressure fields on 500hPa and sea level, is also presented for each season. For whole period 205 days with such events, which can be described by 96 synoptic situations are identified. Increasing tendency of annual number of days with heavy precipitation is occurred during the 27 years period of investigation. About 74% of all days are during the summer and autumn. They are distributed in 3 main synoptic circulation type groups, which present about 65% of all determined torrential precipitation events for these two seasons. The analysis reveals that more than 80% of cases examined, have caused different degrees of damages and even the death of people.

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