RESEARCH OF GEOGRAPHIC STRUCTURE AND EARTHQUAKE In Press RESEARCH OF GEOGRAPHIC STRUCTURE AND EARTHQUAKE Climatological Aspects of Extreme Precipitation Events over Central Plateau of Iran – A Synoptically Point of View

This paper describes the results of an analysis of extreme rainfall events in the central plateau of Iran.To study the extreme events, daily records of eighteen stations ’ rainfalls in the region for different initial dates up to 2005 gathered from the bureau of meteorology.Then, the extreme rainfall threshold was calculated for each individual station using the statistical index of Gamble type I.Lastly, 22mm was determined as the extreme rainfall value for the entire stations, and eventually 17 out of 169 extreme precipitation events were extracted in accordance with three factors including a) days with precipitation in not less than 50 % of the stations, b) maximum rainfall is 22mm or more in at least one of the stations, and c)mean precipitation of the basin is more than 3mm.In the next step to analyze the synoptic features,the relevant meteorological data i.e. relative vorticity, geopotential height, sea level pressure, u and v wind components, relative humidity, vertical velocity, and precipitable water content at multiple levels of the atmosphere were examined from the NCEP/NCAR reanalysis dataset. The synoptic findings indicate that two patterns of deep trough and high ridge of the eastern Mediterranean were responsible for making the heavy precipitation events over the central plateau of Iran. The most and severest rainfall events occurred via deep tough pattern, which covered 76 % of days with extreme precipitations during the examined period. Furthermore, the results suggest that the main moisture resources,which identified by HYSPLIT model’s outputs and moistur