Evaluation and Comparison of the Efficiency of the Total Precipitable Water Vapor Algorithm of MODIS and AMSR2 over Land in the Western Part of IRAN

Total Precipitable Water Vapor is one of the important parameters in meteorology and hydrology. The aim of this study is the evaluation of remote sensing algorithms to estimate TPW over land using microwave and optical wavelengths in the western part of Iran. In this regard, the algorithm of TPW estimation in the microwave wavelength range by using Advanced Microwave Scanning Radiometer 2 (AMSR2) data on cloudy and clear sky days as well as the product of near infrared TPW of Moderate Resolution Imaging Spectroradiometer (MODIS) MOD05 in clear sky days were evaluated. MOD05 product does not work on cloudy days. The evaluation results based on radiosonde data on clear sky days showed that MOD05 product had higher precision than AMSR2 algorithm, so that the coefficient of determination (R2) derived from AMSR2 and MOD05 were 0.516 and 0.650, respectively. Moreover, the Root Mean Square Error (RMSE) of AMSR2 and MOD05 were acquired as 5.129 and 4.542 mm, respectively. On cloudy days R2 and RMSE of the obtained TPW from AMSR2 algorithm were 0.284 and 7.367 mm, respectively. Overall, on cloudy and clear sky days, the value of R2 and RMSE of estimated TPW from AMSR2 was 0.420 and 5.976 mm, respectively.