Indian National Satellite (INSAT) 3A was launched in the year 2003 with communication and remote sensing payloads. The later payloads contain very high resolution radiometer (VHRR) and charge coupled devices (CCD) camera. In this paper, post-launch calibration of INSAT 3A CCD is discussed. A cross radiometric calibration was carried out with well calibrated advanced wide field of view sensor (AWiFS) of Indian Remote Sensing Satellite (IRS P6). Three concurrent scenes of December, January and February were used in this study. Calibration was carried out under different land cover classes such as snow, vegetation, forest, water and cloud. Regression analysis suggests correlation coefficient of 0.95, 0.92 and 0.60 for Red, NIR and SWIR channels with slope values 1.839, 1.589 and 2.232, respectively. New calibration coefficients were used to estimate at-sensor radiance and reflectance in all the three channels. Dynamic range of reflectances was found to be improved by using new calibration coefficients. Normalized difference snow index and vegetation index (NDSI and NDVI) have shown an improvement with new coefficients and were found closer to represent in situ data of different land covers and cloud.
Volume 131, 2022
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