Atmospheric correction scheme for GLI with absorptive aerosol correction

Abstract

The present study proposes an atmospheric correction scheme for Advanced Earth Observation Satellite II (ADEOS-II)/Global Imager (GLI) ocean color retrieval that corrects for the atmospheric absorptive aerosol effect. Radiative transfer simulations were conducted assuming a non-absorptive model aerosol with a soot-type aerosol at various mixture ratios. The results indicate that while the spectral dependency of aerosol reflectance does not change in the longer (>550 nm) wavelength region, the reflectance at shorter wavelengths is highly variable and depends on the mixture ratio. The influence of aerosol absorption was also investigated using GLI data from ocean areas adjacent to Japan in the presence of absorptive Siberian fire smoke aerosol in the spring of 2003. The spectral curvature of the aerosol was estimated from the data obtained. An empirical, iterative scheme that detects and evaluates the influence of absorptive aerosols was developed by comparing 380 nm GLI-observed aerosol reflectance with predicted reflectances derived using an in-water optical model. To evaluate the performance of this scheme, satellite-derived normalized water-leaving radiances were compared with those measured from a ferry servicing Nagasaki and Fukue. The results of data acquired on March 20, 2003, indicate that this absorption correction scheme improved root mean square estimation error for normalized water-leaving radiance by approximately 40% in the 380, 400, and 412 nm bands. This atmospheric correction algorithm was used as a part of the second version of the GLI standard ocean color data process system at Japan Aerospace Exploration Agency (JAXA).