Synoptic Analysis of Farin Colds of Iran

One of the main branches of synoptic climatology is the identifying Farin modes, environmental specifications and determining their inducement circulation patterns.The main objective of this research is the analysis of Farin colds in Iran. For this purpose, the daily statistics of the temperature related to 663 climatic and synoptic stations in the under study area, during the statistical period of 21, March 1962 up to 20 March 2003 (15701 days) were used. Then by the use of Keriking interpolation method with 18 × 18 Km cells, a 15701× 5214 matrix was provided. The average of daily temperature for the given zone (5214 cells) was calculated during the understudy period. The days during which Farin colds has been occurred were recognized by Fomiyaki index. Then the data were ordered based on the cold severity and under cover spectrum. Among the days with Farin colds, the first 500 days were selected as the sample. The selected days were nearly as much as 2 standard deviations lower than their average long term based on Fomiyaki index. The amount of sea level pressure with time- location segregate of 2.5 × 2.5 degree and 6 hours for 500 sample days were derived from Meteorology Organization and Oceanography of the United States of America. By cluster analyzing on Oglidos distances, the amount of sea level for 500 were selected which showed that Farin colds of Iran are the result of 5 circular patterns including: 1-high pressure pattern of Siberia- Europe, 2-High pressure pattern of Siberia, Low pressure pattern of Iceland, 3-High pressure pattern of Siberia, 4-High pressure pattern of North Caspian sea- Siberia, 5-High pressure pattern of Caspian Sea.