Spatiotemporal Variations of Total Cloud Cover and Cloud Optical Thickness in Iran

A knowledge of cloud properties and spatiotemporal variations of clouds is especially crucial to understand the radiative forcing of climate. This research aims to study cloudiness in Iran using the most recent satellite data, powerful databases, and regional and seasonal analyses. In this study, three data series were used for the spatiotemporal variations of cloudiness in the country: A) Cloudiness data of ۴۲ synoptic stations in the country during the statistical period from ۱۹۷۰ to ۲۰۰۵, B) Cloud Optical Thickness (COT) of Terra and Aqua MODIS sensors for ۲۰۰۳-۲۰۱۵, and C) Total Cloud Cover (TCC) of ECMWF Database, ERA-Interim version, for ۱۹۷۹-۲۰۱۵. The values obtained in the country were located via the kriging geostatistical method by RMSE. The results showed that the highest TCC occurs during the winter months. At this time of the year, the cloud cover is reduced from North to South and from West to East. Besides, COT showed that in the cold months of the year, the highest COT is observed in January and the lowest in March. The west and central Zagros highlands have the highest COT. Incorporating COT and TCC results showed that the two factors of height and approximation and access to moisture sources contribute significantly to the regional differences of cloudiness in Iran.

Keywords:

COT , TCC , ECMWF database , MODIS Sensor , Iran