سرماهاي وزشي ايران (مطالعه موردي: سرماي وزشي بهمن 1361 سنندج)

Cold advection of Iran (Case study Jan-Feb 1983 in Sanandaj station)

In this paper, we have used daily minimum temperature data of Sanandaj station during 1961-2002(1339 to 1381 Persian calendar). 85 days of the period has been considered as cold days with temperatures less than - 20"C. The maps of air temperature, V wind and U wind components of this period have been provided for 500, 700, 800, 850, 925and 1000 hpa levels using Grads. A cold period from 1983/1/26 to 1983/2(1361/11/6 to 1361/11/13 Persian calendar), selected based on the maps. These maps showed that the cold advection was domination in the period. For these days, maps of geopotintial height. air temperature, V wind and U wind components for 500 hpa have plotted. In this period a great part of Iran especially Sanandaj station located at the western part of a deep trough. It seems that this trough leads cold air from higher latitudes to the region and provided cooling in most regions of Iran especially Sanandaj station.