شناسایی و پهنه‎بندی نواحی دمای فرین سرد ایران

In this study, kriging method applied to mean daily temperature dataset of 663 synoptic and climatic stations from 1961 to 2004 in Iran. So a gridded database of mean daily temperature with 15*15 Km spatial resolution prepared. This database contains 15992 days and 7187 pixels. Based on this grid data extreme temperature database has been calculated using Normalized Temperature Deviation Index. Then extreme temperature database sorted according to Mean Normalize Temperature Deviation Index and extremeness of cold events. The first 500 days that were coldest, most extended and Mean Normalize Temperature Deviation Index ≤-2 selected as samples. Then NTD matrix for these 500 days (500*7187) analyzed to find extreme cold temperature regions of Iran. Cluster analysis by Ward method has been carried out on 500 days of extreme cold temperature days of Iran. The results of cluster analysis showed that Iran may be divided into six different regions. Geographical configuration of these regions is mainly controlled by the neighboring to big water mass and mountain blocks. In the other hand, Geographical configuration of regions explanatory of extreme cold air mass influx toward Iran.