Assessment of trends and spatial pattern seasonal and annual cloudiness in Iran

The water cycle and the formation of clouds in different climates are very important. Cloudiness and trends in the spatial distribution days to decide and environmental strategies are important. The aim of this study was to investigate the temporal and spatial variations days of annual changes in cloudiness is based on geostatistical methods. Methods based on data cloudy days were 43 synoptic stations from 1970 to 2010. In order to determine the spatial pattern of different methods of geostatistical interpolation was used. The measurement accuracy of the methods of validation criteria MAE, MBE and RMSE and to assess the trend of Kendall and least squares method was used. The results showed that from North to South and from West to East, Iran, the number of cloudy days is reduced and large spatial differences in the number of day's cloudiness in the country. Distribution Spatio-temporal cloudy days in the country is subject to component location and latitude factor is most effective. Results Criteria validation showed that for cloudiness Annual methods GPI and C / K and in winter interpolation method C / K, in the spring of IDW, in the summer LPI and autumn approaches RBF and EBK greater performance in the spatial distribution cloudiness of Are. The cloudy days in the country was further reduced so that more than half of the stations studied, show the significant decreasing trend. Since the introduction of cloudiness is precipitation, results in the management of risks disasters awareness and management of water resources are important.