Ecology, Environment and Conservation Paper

THE STUDY OF WIND SPEED MONTHLY CHANGES TREND IN WEST OF IRAN

Ahmad Rajabi, Saeid Shabanlou and Fariborz Yosefvand

Abstract

Regarding the recent wind speed fluctuations due to global warming and the effect of wind speed on the wind erosion and evapotraspiration, studying wind speed trend seems necessary. This study makes use of wind speed average data of 4 synoptic stations in west of Iran at monthly and yearly time scale in 1951- 2005 time period. The study of wind speed data trend was carried out by making use of Mann-Kendall and Spearman’s Rho tests and linear regression analysis. According to the results, the area is not a homogeneous one during the data period regarding wind speed. The results of the two tests, Mann-Kendall and Spearman’s Rho are the same. In the mentioned stations, there are both increasing and decreasing trends in the monthly and yearly wind speed data. Yearly increasing trend is in Hamedan station and yearly decreasing trend is in Kermanshah station. Wind speed yearly trend is not significant in Khoramabad and Sanandaj stations. Yearly average wind speed increased in most of stations from about 1997. The highest monthly increasing trend was in Hamedan station in May to October. The highest decreasing trend was in Kermanshah station in March, April, September and October.