Restoring Wet Troposhere Data in Retrieving Water Level from Minor Track of SRAL Over Srisailam Reservoir, India

Satellite altimetry has made significant studies in recent times and is now proving to be a highly effective tool for monitoring inland water bodies. Srisailam Reservoir, a crucial multipurpose reservoir situated on the Krishna River in India, is of particular interest. The Sentinel-3A (S3A) satellite, equipped with SRAL (Synthetic Aperture Radar Altimeter) incorporating $K_{\mathbf{u}}$ and C-bands, assists in accurately recording range values and conducting atmospheric corrections. The S3A includes two pass tracks over this reservoir, with the main pass situated close to the dam site, effectively covering a significant portion of the footprints. This main pass has exhibited successful results with minimal error, as documented in the DAHITI database. This study centres on retrieving water levels from a minor track located at a considerable distance from the major track. The methodology outline involves calculating water levels by subtracting the range and associated corrections from the altitude in relation to the mean sea level (MSL). Among the various atmospheric distortions, wet tropospheric correction (WTC) stands as a major concern due to the impact of moisture in the path of the atmospheric signal. Individual analysis of WTC is carried out to overcome data loss. With this implementation, this study achieved WL retrieval with successful data retrieval. The correlation error between retrieved WL and Filed WL (Central Water Commission of India) is quantified as 0.98.