Gangwar, RK; Thapliyal, PK (2020). Retrieval of total precipitable water from thermal infrared observations of INSAT-3D imager over the ocean. CURRENT SCIENCE, 119(2), 382-389.

The present study aims to develop a retrieval algorithm for total precipitable water (TPW) over the ocean using Indian geostationary satellite INSAT-3D observations. The algorithm computes TPW as the sum of two broad layers using thermal infrared observations of the Imager for clear sky and upper tropospheric humidity (UTH) products. First, the differential absorption of the atmospheric water vapour in split-window channels is exploited to estimate atmospheric water vapour concentration from surface to mid-troposphere. Secondly, the contribution from UTH products available from the INSAT-3D Imager is added to estimate TPW. The algorithm performance has been assessed by comparing the INSAT-3Dretrieved TPW with collocated TPW products from radiosonde, INSAT-3D Sounder and Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua satellite for the year 2018. The standard deviation of the error was found to be around 0.5 cm for each of the months.