Investigating the Effect of Relative Spectral Response on the Estimation of Atmospheric Parameters: A Case Study of Landsat 8 (OLI) and Sentinel 2 (MSI)

Accurate estimation of atmospheric parameters is crucial for accurate atmospheric correction as well as aerosol retrieval. While spectral responsivity within a spectral band is much higher at central wavelength, the sensor is sensitive across the entire bandwidth, thereby increasing the possibility of differences in atmospheric parameters estimated using only the central wavelength as compared to that using the relative spectral response (RSR). In the present study, an attempt has been made to investigate the differences in the values of different atmospheric parameters and the consequent impact it has on surface reflectance (SR) estimation and aerosol optical depth (AOD) retrieval from Operational Land Imager (OLI) sensor onboard Landsat 8 and Multispectral Imager (MSI) onboard Sentinel 2. The SR has been estimated from the top-of-atmosphere signals using the Simplified and Robust Surface Reflectance Estimation Method (SREM). AOD has been thereafter, retrieved using a simplistic physics-based approach in single scattering approximation. The results suggest that though the difference in RSR and central wavelength derived parameters is quite small in absolute terms, the effect of RSR is more evident in case of green spectral band for Landsat 8 and in blue band for Sentinel 2. The difference in retrieved AOD is more pronounced in case of OLI as compared to MSI, with difference being more in green band for the former and in blue band for the latter.