The atmospheric correction algorithm for HY-1A/COCTS

Abstract

China has launched the first ocean color satellite HY-1A on May 15, 2002, which carried two remote sensors. The Chinese Ocean Color and Temperature Scanner (COCTS) is the main sensor on HY-1A, and it has not only eight visible and near-infrared bands similar to the SeaWiFS, but also two more thermal infrared bands to measure the sea surface temperature. Therefore, COCTS has broad application potentiality, such as fishery resource protection and development, coastal monitoring and management and marine pollution monitoring. In this paper, the standard atmospheric correction algorithm of COCTS is expatiated firstly, and the reasons why this algorithm and some other atmospheric correction algorithms for turbid waters fail in china coastal and inland water are analyzed. The result shows that not only the non-neglected water leaving radiance at near-infrared bands, but also the error of the aerosol single scattering reflectance between bands 7 and 8 for COCTS. On the base of analyzing the principle of the water-leaving radiance varying with the sediments concentration, we have developed an atmospheric correction algorithm in turbid waters for COCTS, which eliminates the over correction and negative water-leaving radiance at blue wavelength bands in China coastal and inland waters, and the result shows that the normalized water-leaving radiances derived by this algorithm accord with reality much better. By comparing with the SeaWiFS data, it shows that the atmospheric correction algorithm of COCTS is reliable, and the water-leaving radiance derived from COCTS data is consisted with SeaWiFS data.