Clustering the rainfall of Iran with using new approach based on Singular Value Decomposition Mapping and Fuzzy C-Means Clustering

The aim of this study is clustering of Iran precipitation in order to recognize its spatial differences. Daily data of precipitation, relative humidity, and due point temperature were acquired from 63 stations since the year 1980 till 2013 by national meteorology organization. These primary data by using of the method Singular Value Decomposition (SVD) mapping were compressed to single values and then decreased and prepared as non-linear properties. In addition to these properties, some other properties such as the days with heavy precipitation (greater than or equal to 10 mm), days with much heavy precipitation (greater than or equal to 20 mm), days with precipitation greater than or equal to 25 mm, greatest number of consecutive dry days (CDD), greatest number of consecutive wet days (CWD), and the number of days with precipitation at every season were acquired as linear properties of daily precipitation. In the final step, these linear and non-linear properties were joined together then entered to the fuzzy clustering system. The result of this study showed six precipitation clusters in Iran. The coastal areas of the Caspian Sea, Persian Gulf and Oman Sea, the central very dry, semi-arid, mountainous and semi-mountainous areas were grouped in definite clusters according to Iran topography, Latitude and distance from the sea and water resources. Comparing the results of clustering by this method with other methods that have been done until now, we found that this new approach of clustering can distinguished the stations and clusters regarding its causative agents, significantly high performance.