Prediction model for Anzali precipitation by using upper levels dynamic and thermodynamic variables in Caspian Sea

Precipitation is one of the most complicated atmospheric phenomena. Condensation nuclei, humidity and uplifting are important in producing cloud and precipitation. Caspian Sea, as an important humidity source in the north of Iran can feed humidity into rain systems. In order to survey the synoptic conditions in Anzali station, daily data in upper levels and daily precipitation were provided and dynamic and thermodynamic variables were calculated in 1000 to 100(hpa) levels in 2003. Then, precipitation prediction models were estimated using multiple regression analysis and stepwise method for each of Caspian region nodes in varies precipitation groups. At last, final prepared for each of precipitation groups. These models show that the first candidate variable in the precipitation group of higher than 50 mm is vorticity(1000 hpa, 8 node), in the precipitation group of higher than 40 mm is omega(600 hpa, 1 node), in the precipitation group of higher than 30 mm is relative humidity(850 hpa, 22 node) and for total precipitation it is geopotential height(925 hpa, 29 node). The maps show that in the most of models, candidate variable particularly uplifting dynamic factors locate on lands. Adjusted for final model is more than %81 for total precipitation.