Evaluation of radiometric performance of MODIS visible bands using the Rayleigh scattering method

Abstract

The Moderate Resolution Imaging Spectroradiometer (MODIS) has provided a large number of high-quality remote sensing data for Earth observation since its launch. Although the reflectance data is calibrated by on-board calibrators, it also needs to be verified by other independent methods in order to ensure the accuracy and reliability of the data. Thus, the Rayleigh scattering method is used to evaluate the MODIS/Aqua reflectance data in our study. In order to obtain high-precision Rayleigh scattering calculation results, the atmospheric and oceanic parameters (AOPs) corresponding to the local time and place, such as wind speed, aerosol optical depth, ozone amount, chlorophyll concentration, and seawater salinity, are put into a radiative transfer model to calculate after a series of screening. The current research selects the pixels with strong Rayleigh scattering characteristics in four days from a global ocean scene. The simulated reflectance is compared with the MYD021KM reflectance product in five visible bands, which presents the total uncertainties as, respectively, 1.39% (412 nm), 0.14% (469 nm), −0.18 % (488 nm), −0.47 % (531 nm), −0.41 % (551 nm). The verification results prove that the MODIS reflectance product remains at a high level of precision without significant deviation after having operated in orbit for 16 years, and the MODIS product has high interband self-consistency. The sensitivity analysis shows that the wind speed and chlorophyll concentration perturbed more to the simulated reflectance than other AOPs of the selected samples. It is believed that the methodology can be applicable to other visible light sensors for validating their reflectance product accurately.