عنوان مقاله [English]
Western of Iran located from point of view atmospheric macroclimate in the moderate zone with four season. This spatial located as well as cause western of Iran affected some main climatic signal and action center and huge atmospheric centers and other side cause atmospheric circulation pattern in per season of western affected by motion of North and South ward sun assign special form.
For per formance this paper temperature upper of forty degree centigrade threshold in summers of Western of Iran and it connection of local pressure or STHP indexes investigated statistic of synoptic stations Khorramabad, Kermanshah, Sanandaj and Hamadan synoptic station of Khorramabad statistic in twenty six annual period(1985-2010)with annual average twenty five day most upper, Kermanshah station with fifteen days, Sanandaj with five days and Hamadan with one day. Are most days with forty degree centigrade threshold and upper are next order.
In this paper use F.A and cluster analysis for classification and determine of synoptic patterns in order that use daily average data in SLP, 850 and 500 HP levels in study period in grid 25 degree. This data take of data set analysis NCEP/NCER. Study limitation surrounded 10-60 degree latitude and 0-90 degree longitude and composite 693 grid with location perceeise geographical 2.5*2.5 degree.
Conclusion of factor analysis indicated that over all three synoptic pattern cause of temperature threshold forty degree centigrade and upper that ninety selected case have three synoptic pattern. That seventeen case in first pattern; forty five in second case and forty eight case are in third case pattern.