Estimation and validation of enhanced resolution brightness temperature products of SCATSAT-1

Abstract

The brightness temperature (Tb) is considered a fundamental climate data record that governs the radiance traveling towards the satellite from the top of the atmosphere. It is used to derive the wind speed, cloud liquid water and sea surface temperature. The optical sensors play a vital role in the retrieval of Tb but also affected by the clouds and different solar illuminations. On the other hand, scatterometer offers the day/night data delivery even in cloudy conditions and insensitive towards solar illuminations. Scatterometer Satellite (SCATSAT-1) based on Ku-band (13.5 GHz), is launched by ISRO (Indian Space Research Organization) on 26th September 2016. Besides backscattering coefficients (sigma-naught and gamma-naught), SCATSAT-1 also provides the Tb for slices and footprints that are derived from scatterometer noise measurement, expressed in units of the temperature (deg. K). The SCATSAT-1 Level 4 Tb product is available at two different polarization modes i.e. HH and VV. The main objective of this study is to retrieve the Tb at HH and VV over a part of Western Himalayas (Himachal Pradesh, India) using the SCATSAT-1 backscattering and validating the results using MODIS (Moderate Resolution Imaging Spectroradiometer) data. Based on similarity measures, it is found that SCATSAT-1 achieved the well-correlation [R squared 0.8311 (for VV) and 0.8343 (for HH)] with MODIS Tb. This study can be utilized in many remote sensing applications in flood detection or other natural disasters.