ناحيه بندي سينوپتيك دماي منطقه خزر بر مبناي متغيرهاي ترموديناميك ترازهاي فوقاني جو

Synoptic Regionalization of Temperature in the Caspian Sea Region Using Thermodynamic Variables of Up - level Atmosphere

Temperature is one of the most important effective factors on climate and environment. The Caspian Sea, the vast water body in the North Iran, has the important proportion in controlling the fluctuation of temperature. To survey the synoptic conditions and determinate the effect of thermal regions and factors on them in the Caspian Sea, the daily atmospheric data of different levels were cottected from 1994 to 2003 and the indicators of thermal situation such as air temperature, potential temperatured and thermal advection from 1000 to l00hp levels were calculated. Then the maps map of thermal regions for atmospheric columns from 1000 to 100 hp and maps of thermal regions for 300, 500, 700, 850 and l000hp levels were drawn by using principal component and cluster analysis in the Caspian Sea. The results showed that there are seven regions for each the thermal indicator, of which latitude and synoptic systems particularly the Asia high pressure in the cold seasons in the east and north east Caspian Sea decrease temperature and immigrating low and high pressure systems in west and southwest increase temperature are the most important factors effective on separating the thermal regions in different levels. Also the results of comparing the maps of thermal regions (air temperature, potential temperature and thermal advection) showed that land and water areas do not separate Therefore, the role of huge water body for making spatial distribution and thermal regions is weak and probably its effect on local and meso scales is in some specific period of the year by transporting energy and generating breeze of land-sea. Overal there is averagely a temperature difference of 7-10°C between the north and the south, ond 2-3°C between the east and the west, and the coldest region is located hn the north east.