On the relationship between zonal wind variations and precipitation of southern regions of Iran

Subject Areas : Article frome a thesis

Amin Shirvani ¹ , Noushin Ahmadi Baseri ²

1 - Shiraz University
2 - فارغ التحصیل کارشناسی ارشد هواشناسی کشاورزی، بخش مهندسی آب، دانشکده کشاورزی، دانشگاه شیراز، ایران.

Received: 2014-10-01 Accepted : 2019-02-27 Published : 2019-02-20

Keywords: Iran, precipitation, Principal components analysis, Empirical orthogonal functions, Zonal wind,

Abstract :

In this study, the relationship between the precipitation over the southern areas of Iran and zonal wind over the Middle East was investigated. The monthly zonal wind data at 200hPa over the Middle East was selected from reanalysis NCEP-NCAR. The principal components analysis was applied to extract the signal modes of the winter (JFM) wind variations. The first empirical orthogonal function was spatially plotted and those grid points with high loading, which had the important role in the first principal component, were determined. These grid points are located in 15 to 22.5 and 27.5 to 42.5. The average of zonal wind within this area was considered as a regional index and the relationship between this index and winter precipitation for 11 synoptic stations in the south of Iran for 1968-2010 was investigated. The results indicated that there is a positive significant correlation at 5% level between wind index and precipitation over the most stations. The constructed wind index has stronger relationship with precipitation over the study area in comparison with southern oscillation index and Persian Gulf sea surface temperature.

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