Temporal Distribution and Regime of Precipitation of Northwest of Iran

Precipitation regime refers to distribution of seasonal- monthly precipitation. By studying this character، it could be find out about the most important parts of mechanism (s) dominant in temporal distribution of precipitation. Precipitation regime can have positive or negative effects on other environmental components performance. In the present research، the monthly data in 73 stations during 1966-2005 have been analyzed to describe precipitation regime in North West of Iran. In order to do the study، three precipitation indices (coefficient of variation، homogeneity Index and seasonal index were used. Indices have shown same characters of precipitation regime. Results show that minimum value of precipitation coefficient of variation and maximum homogeneity occurring in north-east region. This part have homogeneity precipitation regime with a humidity season that showing different precipitation systems are activate. South-east region have a completely temporal-concentration precipitation regime. It refers to more effect of concentrate systems special in a season. There are in 80% of region with seasonal precipitation regime have a short dry season.