Publications

Parihar, S; Mitra, AK; Bhatla, R (2022). Stability of ground site for calibration and validation activities of INSAT-3D for weather application. JOURNAL OF EARTH SYSTEM SCIENCE, 131(3), 193.

Abstract
In-situ vicarious calibration method for INSAT-3D imager visible (550-750 nm) has been carried out for characterizing the radiometric uniformity of the site. The field campaigns were conducted over two sites Thar Desert, Jaisalmer and Bhuj, Gujarat, during 2013-2017. The measurements of ground reflectance using a Spectroradiometer (spectral ranges 350-2500 nm), aerosol optical depth (AOD) using a sunphotometer and total column ozone using an Ozonometer, respectively, and other meteorological variables were obtained. Based on these measurements, simulations of radiance reaching the top of the atmosphere (TOA) was carried out using radiative transfer model 6S (second simulation of satellite signal in solar spectrum). Calibration coefficients of INSAT-3D were estimated by linear regression analysis based on INSAT-3D measured and 6S simulated radiance for both the sites. For the Jaisalmer site, the results suggested a very high relative error between INSAT-3D measured and 6S derived radiance with high spectral variability in ground reflectance and less statistical correlation. Whereas, for the Bhuj site, close agreement was observed between INSAT-3D measured and 6S derived radiance with uniform ground reflectance for all the days of the campaign. The mean difference in the relative errors is <3% over the Bhuj site. In addition, to check its suitability, the temporal and spectral stability of the Bhuj site was also analyzed using moderate-resolution imaging spectroradiometer (MODIS) and advanced very high-resolution radiometer (AVHRR) data. The analysis suggested that the Bhuj site has been preferred for post-launch vicarious calibration of the optical sensor of INSAT-3D/R satellites as well as the upcoming geostationary INSAT satellite series.

DOI:
10.1007/s12040-022-01925-x

ISSN:
0973-774X