Satellite Estimation of Precipitable Water Vapor (PWV) in Iran Atmosphere of Iran and the Analysis of its Spatial Correlation with Meteorological Variables

Precipitable Water Vapor (PWV) is one of the most important quantities in meteorology, atmospheric physics, hydrology and climate change studies, which its estimation is useful in predicting precipitation, flood occurrence and other hydrological parameters. Today, satellite imagery is widely used to estimate PWV and analyze its correlation with other meteorological Variables. The objective of this study was to estimate the amount of PWV and to investigate its relationship with six climatic variables such as; temperature, pressure, relative humidity, cloudiness ratio, precipitation and wind speed in the geographical area of Iran using satellite-based data.The proposed data with monthly time steps and 1°*1° spatial resolution were selected in the climatic range of Iran's atmosphere for the period of 2003-2019. Pearson correlation coefficient was used to investigate the relationship between PWV and the above mentioned climatic variables. Digital data extracted after qualitative control and pre-processing were used by specialized software such as ENVI, ArcGIS and Grads to build raster layers based on the geographical boundary of Iran.  According to the results, the average PWV in the atmosphere of Iran is 12.7 mm, which shows a lower amount as compared to the global average (21.6 mm). On the other hand, the amount of PWV in the Atmosphere of Iran does not have a temporal and spatial homogeneous distribution. So that the highest amount of PWV is concentrated in the coastal area of south and north and the lowest amount is concentrated over the Zagros mountain range, parts of northeast and east of Iran and in the next priority in the desert areas of central Iran. The Pearson correlation coefficients between PWV and the meteorlogical variables were 86% for air temperaure, - 89% for pressure, - 88% for relative humidity, - 32% for cloudiness ratio, - 64% for precipitation and  67% for wind speed.