Document Type : Research Paper
Authors
1 Tabriz University
2 The University of Tabriz
3 University of Mohaghegh Ardabili
Abstract
Strong winds are one of natural disasters that sometimes cause enormous Financial and physical damages. Since northwest of Iran and specially Ardabil Province is one of windy regions, this study tried to identify synoptic patterns which bring strong winds. Through considering equal and threshold wind speeding over 28 knots per second, 783 days identified as wind crashing days in Ardabil province. Then by data component- based analysis of 500hPa geo-potential height of the 783-days detected seven components which explain 92% of variance. Finally by clustering seven components identified ten patterns as synoptic patterns that are responsible for Strong wind of Ardabil province. The survey of topographic arrangement of these patterns indicates the rise of trough and ridge levels to these patterns. This means that the patterns consists of, mainly, trough, ridge, or combination of both and aren’t observed other systems such as cut off, block systems, etc. Although mentioned systems may be observe in individual patterns of each of the 783 days, but the systems aren’t responsible for the dominance and influence. The temporal distribution patterns show that two patterns, 6 and 7which occurs in the summer, has a similar system at 1000 hPa level when it compares with other models which occur in winter, spring, fall. What's notable, reversal of location position of pressure systems, 1000 hPa, in two patterns of summer, so that a low pressure instead of high pressure is over the Zagros and a high pressure instead of low pressure is over the Caspian Sea.
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