توده هاي هواي موثر بر ايران در دوره سرد سال

The Airmasses Influencing Iran During Clod Seasons

In this research which is based on synoptic Climatology procedures including synoptic maps interpretation and statistical analysis, the air masses influencing Iran, in three stations: Tehran, Shiraz and Kermanshah based on the temperature and dew point, daily upper air data surface, 850,700,500 hecopascal for the years 1981-90 were studied. Also in this research in order to identify the air masses, based on the conservation of air mass properties law, the following parameters: potential temperature, wet bulb potential temperature and mixing ration were selected, and Calculated. statistical analyses such as principal component and cluster analysis were done. Given all the information above the results are as follow: For Tehran station 4 Shiraz 3 and Kermanshah 3 factors were extracted, and based on these factors hierarchical cluster analysis for aggregate days was applied and then mean analysis for all data was done. With comparing the average value of all parameters in each groups and comparing them with the data of Aswan, Ashkhabad and Mediterranean air mass properties, these air masses tmA,cA,cP,mT,cT and med. were determined. And then based on the data of potential temperature and mixing ratio of 500 hectopascal index days was extracted and tephigrams for these days were prepared and their synoptic maps were studied.