Scholarly record
LONG-TERM VARIABILITY OF PRECIPITATION IN BULGARIA - COMPARITIVE ANALISIS FOR TWO CLIMATIC PERIODS
Abstract
The main objective of this study is to outline the spatial distribution of precipitation deficit at both monthly and annual scales by comparing precipitation data from two reference periods: 1961–1990 and 1991–2020. To achieve this goal, monthly and annual precipitation normals from 355 meteorological stations throughout the country are calculated in accordance with the World Meteorological Organization's standards. Data post-processing, statistical analysis and spatial interpolation are performed in the R environment using scripts developed for this study. The freely available QGIS software is used to visualize the obtained spatial patterns. The results show that the average annual and, more importantly, most monthly precipitation do not change significantly in the second period compared to the first, due to the opposite signs of change across individual regions. Notably, the largest deviations in average precipitation, both positive and negative, are observed in autumn: September (+34%), October (+43%), and November (-13%). Although in most of the country the differences in monthly precipitation between the two periods are generally within ±10%, some significant regional changes in the precipitation regime are evident. In the mountains, annual precipitation decreases significantly (by 20-30% in high-altitude areas), while in Northeastern Bulgaria, it increases by 30-40% in some places.
Publication details
References15
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