Vicarious calibration of KOMPSAT-3A with ground tarp and meteorological measurements

Abstract:

The KOrea Multi-Purpose SATellite-3 (KOMPSAT-3A) developed by Korea Aerospace Research Institute (KARI) is the first sub-meter optical satellite of South Korea with IR sensor. This paper describe the first radiometric characteristics of KOMPSAT-3A by carrying out vicarious calibration with reference to well-known surface tarps. The field campaigns are performed to measure spectral of surface tarps with hand-held ASD spectroradiometer. When performing field measurement, KOMPSAT-3A multispectral images are acquired at same time to reduce atmospheric and observation geometric discrepancies. The estimated spectral of surface reflectance from tarps are used as input values of 6S radiative transfer model to predict radiance at sensor level. The present study, 6S radiative transfer model is used by inputting various initial parameters such as spectral response function of KOMPSAT-3A, atmospheric condition, and relative sensor-target-solar geometry. In the case of atmospheric products, multifilter rotating shadowband radiometer (MFRSR) measurements and MODIS atmospheric products such as aerosol optical depth, water vapor and amount of ozone are used for interpreting solar radiation scattering and absorption effects. For first field campaign, the gain coefficients from each of multispectral bands are estimated by comparing predicted radiance at sensor level and digital number (DN) of KOMPSAT-3A based on leaner least square fit. To analysis firstly estimated radiometric calibration, surface reflectance of tarps in second field campaign is used as reference target to validate its radiometric characteristics. And second field campaign measurements are also used to upgrade KOMPSAT-3A DN to radiance coefficients. Reliable radiometric values are suggested by using surface tarps, MFRSR and MODIS products, indicating those information are useful for KOMPSAT-3A user group for continuous variables of quantitative applications.