INSAT-3D and MODIS retrieved sea surface temperature validation and assessment over waters surrounding the Indian subcontinent

The INSAT-3D imager (4 km) and Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on-board Aqua and Terra space-platforms level-2 (1 km) sea surface temperature (SSTskin) product accuracy has been analysed over waters surrounding the Indian subcontinent by indirect comparison method using collocated bulk in-situ measurements (SSTdepth) for 3 years (October 2013-October 2016). Statistical results show that root mean square error of all the three satellites is in range of around 0.600.70 degrees C. Retrieval error is found to be slightly more in case of validation against iQuam data set. INSAT-3D is showing more underestimation with bias ranging from about -0.16 degrees C to -0.20 degrees C than MODIS sensor having bias in range of about 0.06 degrees C to -0.12 degrees C. All the three missions are slightly underestimating over open-ocean with bias ranging in 0-0.17 degrees C. INSAT-3D is significantly underestimating in-situ observations over the Arabian Sea (approximate bias = 0.27 degrees C). Seasonal validation analysis reveals relatively high retrieval error during monsoon season than premonsoon and post-monsoon seasons. MODIS sensor is showing significant underestimation during monsoon with bias ranging from approximately -0.29 degrees C to -0.58 degrees C. Overall, all the three missions are performing similarly well over the study area.