Classification and analysis Synoptic patterns of the most sever wet year Uremia Lake Basin during 1977-2012

ABSTRACT: The aim of this research is recognizing and Classifying Synoptic patterns of the most severe wet year over Uremia Lake Basin during 1977-2012. After determining rain temporal-local threshold, rainy days spread over Basin were extracted. Then, level 500 HP height data located in a scope of 20-65? northern latitude and 20-65? eastern longitude was formulated as an S-mode matrix for raining days. After that, the synoptic patterns were classified using statistical method of Component Analysis and Ward`s clustering method. Finally, the composite map of each cluster was prepared and analyzed synoptically. The findings show that at the time of the most severe wet year over the catchments area, synoptic patterns prevailed in to three main groups: Short waves trough, Blocking system, Cut-Off Low system synoptic. So that, these systems play an important role in increasing instability and extreme raining in 1993 in the area.