A thirty year catalogue of mid tropospheric circulation patterns over Iran and its vicinity

Document Type : علمی- پژوهشی

Author

• Sayyed Abolfazl Masoudiyan

https://doi.org/10.22067/geography.v4i7.4176

Abstract

A PCA has been applied to covariance matrix of NCEP/NCAR daily hgt data at 12 GMT from 1974 to 2003 for a region bounded between zero to seventy degree east and ten to sixty north. This analysis showed that thirteen PCs explain about 96 percent of variance in standardized hgt data. Applying a cluster analysis using world’s method on PC scores reveals nine separate circulation patterns. Some of these patterns show seasonal signals and frequency of the patterns change annually. It is likely that seasonal and annual changes of climate of Iran could be explained in terms of temporal behavior of these circulation patterns.

Keywords: Synoptic climatology, circulation patterns, 500 hpa geopotential height, catalogue of circulation pattern.