Remote Sensing of Aerosols and Water-Leaving Radiance from Chinese FY-3/MERSI Based on a Simultaneous Method

Abstract

In this paper, a new simultaneous retrieval method of the SIRAW algorithm is introduced and carried out on FY3D/MERSI-II satellite images to obtain the aerosol optical thickness (AOT) and normalized water-leaving radiance (WLR) over the ocean. In order to improve the operation efficiency of SIRAW, a machine learning solver is developed to improve the speed of forward radiative transfer computation during retrieval. Ground-based measurement data from AERONET-OC and satellite products from VIIRS are used for comparative verification. The results show that the retrieved AOT and WLR from SIRAW are both in good agreement with those of AERONET-OC and VIIRS. Further, considering the degradation of the MERSI sensor, a new calibration scheme on 412 nm and 443 nm is adopted and an evaluation is carried out. Inter-comparison of derived WLR between MERSI and VIIRS indicates that the new calibration scheme could effectively improve the WLR retrieval accuracy of MERSI with better consistency to the official data of VIIRS. Therefore, this paper confirms that a simultaneous retrieval scheme combined with effective calibration coefficients can be used for high-precision retrieval of real aerosol and water-leaving radiation.

Methane Retrieval from Hyperspectral Infrared Atmospheric Sounder on FY3D

“…The medium resolution spectral imager type II (MERSI-II) mounted on FY3D integrates the functions of the original two imaging instruments (MERSI and a visible infrared scanning radiometer (VIRR)) of the Fengyun-3 satellite, and the spectral channels have been expanded from the original 20 channels to 25 channels [31]. Among these, there are 6 visible bands, 10 visible infrared bands, 3 short-wave infrared bands and 6 medium-tolong-wave infrared bands, the spectral coverage range is 470~12,000 nm, and the spatial resolution is 250 m to 1 km [32].…”

“…This is the first imaging instrument in the world that can obtain data regarding the global 250 m resolution infrared split window region. It can obtain global true color images, with 250 m resolution every day without gaps, and the retrieval results for atmospheric, terrestrial and oceanic parameters, such as clouds, aerosols [31], water vapor, surface characteristics [33] and ocean water color, achieved a high accuracy. It provides scientific support for China's ecological management and restoration, environmental monitoring, and protection.…”