University of Tehran Press Journal of the Earth and Space Physics 2538-371X 44 4 2018 12 22 Spatiotemporal Variations of Total Cloud Cover and Cloud Optical Thickness in Iran Spatiotemporal Variations of Total Cloud Cover and Cloud Optical Thickness in Iran 145 164 67759 10.22059/jesphys.2018.248041.1006956 FA Mahmoud Ahmadi Associate Professor, Department of physical geography, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran 0000-0001-8546-0361 Abbasali Dadashiroudbari Ph.D. Student, Department of physical geography, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran Hamzeh Ahmadi Ph.D. Student, Department of physical geography, Faculty of Geography and Environmental Sciences, Hakim Sabzevari University, Iran Journal Article 2018 01 06 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 42 synoptic stations in the country during the statistical period from 1970 to 2005, B) Cloud Optical Thickness (COT) of Terra and Aqua MODIS sensors for 2003-2015, and C) Total Cloud Cover (TCC) of ECMWF Database, ERA-Interim version, for 1979-2015. 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. 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 42 synoptic stations in the country during the statistical period from 1970 to 2005, B) Cloud Optical Thickness (COT) of Terra and Aqua MODIS sensors for 2003-2015, and C) Total Cloud Cover (TCC) of ECMWF Database, ERA-Interim version, for 1979-2015. 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. https://jesphys.ut.ac.ir/article_67759_a2006a1aaf922ab17b6c856a48ce34c9.pdf