عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In order to achieve risk management to reduce losses caused by extreme rainfall in the West of country and to identify the thermodynamic conditions of this phenomenon during a period of 50 years (2010-1961), Skew-T log P climate graphs extracted from the website of the University of Wyoming America were used. Moreover, atmospheric instability indices, SI, LI, Sw, KI, C.T, V.T, T.T, PWC, of Kermanshah province station, in order to full coverage of the region (about 21 cases of extreme precipitation), were used and the results of all the indicators above the standards of atmospheric instability were compared and evaluated. In this study, discrepancies between observed and predicted values were observed and finally regional instability indices have been determined as it follows: Si ≤ ،71/20 LI ≤ ،63/16Sw ،25/16 ≤ KI ،23/1 ≤ C.T ،50/8 ≤ V و 90/18≤ T.T33≤ the increase of SW, KI, C.T, V.T and T.T to larger numbers than what were listed in the table and the reduction of SI and LI to smaller numbers are a representative of an extreme increase of instability and probability of extreme precipitation. The results showed that the conditions of potential instability in the event of extreme precipitation on the vertical profile of the atmosphere had become dominant. Also, the western system during periods of extreme precipitation is associated with a Mediterranean low-pressure system on the ground and trough in the upper level that is an appropriate model for extreme rainfall and provides humidity for precipitation.