DOI: 10.5593/SGEM2015/B41/S19.137


L. Bocheva, P. Simeonov
Monday 28 September 2015 by Libadmin2015

References: 15th International Multidisciplinary Scientific GeoConference SGEM 2015, www.sgem.org, SGEM2015 Conference Proceedings, ISBN 978-619-7105-38-4 / ISSN 1314-2704, June 18-24, 2015, Book4, 1065-1072 pp

The aim of the study is to present time-space variation of hail events in non-mountainous regions in Bulgaria during the period 1961-2010. Differences in distribution of observed hail fall days in different region of the country are also presented. For this investigation only data from meteorological records of National Institute of Meteorology and Hydrology is used. The annual distribution of number of days with hail fall has a decreasing trend and the maximum value is in the year 1973. There are two factors responsible for the obtained results: cloud seeding for hail supression which began in 1972 with protected area of about 15 600 км² and insufficient density of meteorological stations where this type of phenomenon is recorded. The 75% of all hail days is observed in warm half of the year between April and July. In the same time the significant increase of hail events in all regions from North Bulgaria during the comparatively cold months September, October and March after 1991 is established. During the last 20 years an increase in the number of hail precipitation in winter months is observed in regions from South and East Bulgaria. The regime of wide-spread hail events for 10-days period during the warm half of the year (April-September) is compared for the two periods: 1961-1990 and 1991-2010. The increase in number of those hazardous events during the months from the end of the summer is received.

Keywords: Bulgaria, hail climatology, regional analysis