شناسايي رژيم هاي بارش ايران به روش تحليل خوشه اي

Recognition of Precipitation Regimes of Iran Using Cluster Analysis

In order to detect different precipitation regimes of Iran monthly precipitation observations from Jan 1951 through Dec 1999 have been analyzed. Using this data set 588 monthly digital maps with a spatial resolution of 15 *15 Km have been calculated. Dividing monthly precipitation over each pixel to annual precipitation of that pixel provide the basic data for detecting precipitation regimes. An agglomerative hierarchical cluster analysis then applied to a random sample extracting from relative precipitation matrix. This analysis shows that there are three main precipitation regimes in Iran: winter regime, winter-spring regime and fall regime. Temporal distribution of precipitation in Iran depends mainly on latitude. Meanwhile local geographical features play a crucial role in secondary characteristics of precipitation regimes.