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Heavy Precipitation Forecasting using Neural Networks. A Flash Flood Event in Bulgaria in s ummer 2005 (case study). Ivan Tsonevsky , Weather Forecasting Department, National Institute of Meteorology and Hydrology , BULGARIA. Constanta, 20-26 August, 2006. ANNs in meteorology.
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Heavy Precipitation Forecasting using Neural Networks. A Flash Flood Event in Bulgaria in summer 2005 (case study) Ivan Tsonevsky, Weather Forecasting Department, National Institute of Meteorology and Hydrology, BULGARIA Constanta, 20-26 August, 2006
ANNs in meteorology ANNs for classification problems: • MLP; • RBF; • Kohonen; • PNN; • Linear.
Input Hidden layer Output MLP
Novo selo Silistra Vidin Ruse Lom Oriahovo Belene Svishtov Shabla Dobritch Razgrad Kneja Montana Pleven Kaliakra Vratza Varna Lovetch V. Turnovo Dragoman Sliven Sofia Karnobat Kazanluk Burgas Kiustendil Pazardjik Chirpan Plovdiv Elhovo Ahtopol Blagoevgrad Kurdjali Sandanski ANNs for precipitation forecasts Bulgaria was divided into 6 regions.
ANNs for precipitation forecasts A number ofMLPs were trained: • winter - threshold = 10 mm/12h • summer - threshold = 15 mm/12h • training set: 1998-2004 • 27 input variables from NWP models • 1 output – class of the case (above or below the threshold)
Case study • 1-4.07.2005 Geopotential height at 500 hPa 1.07/00 UTC 2.07/00 UTC 4.07/00 UTC 3.07/00 UTC
Case study • 1-4.07.2005 Mean sea level pressure 2.07/00 UTC 1.07/00 UTC 3.07/00 UTC 4.07/00 UTC
Case study • 1-4.07.2005 Accumulated precipitation amount
207 % 228 % 77 % 80 % 144 % 79 % 167 % 249 % 128 % 43 % 80 % 149 % 169 % 24 % 169 % 124 % 30 % 128 % 40 % 58 % 138 % 261 % 110 % 77 % 47 % 24 % 292 % 150 % 79 % 194 % 85 % 102 % 16 % 21 % 91 % 30 % Case study • 1-4.07.2005 Precipitation rate: Pacc.(1-4.07)/Pmonthly mean
Central part of North Bulgaria; Northeast of Bulgaria; Central part of South Bulgaria. Case study Floods occured and many damages were reported. The most affected areas were:
Case study ANNs:
Case study ANNs:
Case study ANNs:
Conclusions • Neural Network techniques can be applied successfully in Meteorology for classification, analysis and weather forecasts. • In Bulgaria a number of Neural Networks have been trained successfully for regional classification of precipitation events during the cold and the warm half of the year. • Satisfactory results obtained for the extremely wet 2005 by using Neural Networks confirm the benefits from the usage of Neural Networks techniques when severe weather warnings ought to be issued.