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B ulgarian Academy of Sciences N ATIONAL INSTITUTE OF METEOROLOGY AND HYDROLOGY. A Case Study on Utilization of Precipitation Indices in Bulgaria V esselin Alexandrov B . Dubuisson *, J.M. Moisselin *, K.Koleva Ohrid, 2006. *. OBJECTIVES. to explore various (> 40) STARDEX
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Bulgarian Academy of Sciences NATIONAL INSTITUTE OF METEOROLOGY AND HYDROLOGY A Case Study on Utilization of Precipitation Indices in Bulgaria Vesselin Alexandrov B.Dubuisson*,J.M.Moisselin*, K.Koleva Ohrid, 2006 *
OBJECTIVES to explore various (> 40) STARDEX precipitation indices Core precipitation indices: prec90 - 90th percentile of rainday amounts R5d - greatest 5-day total rainfall SDII - simple daily intensity CDD - max number of consecutive dry days R90T - % of total rainfall from events > long- term 90th percentile R90N - number of events > long-term 90th percentile
Weather stations in Bulgaria with long-term records, used in the study
HOMOGENIZATION METHOD The currently used in Météo-France homogenization procedure, which does not require computation of regional reference series, was applied The Caussinus-Mestre method, with a double-step procedure was used to detect multiple breaks and outliers in the previously controlled average precipitation long-term series A two factor linear model was applied for break correction in the precipitationseries
Anomalies of annual precipitation in the weather stations, used in the study, during application of data quality control
- missing - break - outlier Homogenization of monthly precipitation data in weather station Boshurishte – first detection of breaks (triangles) and outliers (A)
validated breaks and then corrected Homogenization of monthly precipitation data in weather station Boshurishte – break correction
annual variability: 90th percentile of rainday amounts (1951-2000)
Annual prec90 trends (1951-2000) by applying the Spearman test; dark red arrows – significant increasing trend; red arrows – increasing trend; blue arrows – decreasing trend; dark blue arrows – significant decreasing trend
Annual R5d trendstrends (1951-2000) by applying the Spearman test; dark red arrows – significant increasing trend; red arrows – increasing trend; blue arrows – decreasing trend; dark blue arrows – significant decreasing trend
Annual SDIItrends (1951-2000) by applying the Spearman test; dark red arrows – significant increasing trend; red arrows – increasing trend; blue arrows – decreasing trend; dark blue arrows – significant decreasing trend
Annual CDDtrends (1951-2000) by applying the Spearman test; dark red arrows – significant increasing trend; red arrows – increasing trend; blue arrows – decreasing trend; dark blue arrows – significant decreasing trend
Annual R90Ttrends (1951-2000) by applying the Spearman test; dark red arrows – significant increasing trend; red arrows – increasing trend; blue arrows – decreasing trend; dark blue arrows – significant decreasing trend
Annual R90Ntrends (1951-2000) by applying the Spearman test; dark red arrows – significant increasing trend; red arrows – increasing trend; blue arrows – decreasing trend; dark blue arrows – significant decreasing trend
CONCLUSIONS The trends (1951-2000) in the core STARDEX precipitation indices, are weak and are not significant in general. The significant trends were observed in separate weather stations or areas only. The trends in most cases are with low spatial coherence. Additional work is planned to be done. Further analysis of precipitation related indices is needed as well as comparison of the results with the ones obtained in different European regions.