The atmospheric correction of ROCSAT-1 OCI imagery - Part I: OCITRAN-1

The atmospheric aerosol effect makes an important contribution to the total radiance in the visible and infrared bands, observed by the Ocean Color Imager on the ROCSAT-1 satellite. For better interpretations of OCI data, an accurate aerosol effect correction is necessary. In this study the concept of clear water is adopted to determine the aerosol effect as part of the atmospheric effect correction model, OCITRAN-1. A clear water area is chosen to assess the aerosol condition and remove the aerosol effect. Two SeaWiFS image sets were used to test the accuracy of the OCITRAN-1 model by comparing its result with those obtained by the SeaDAS model. The comparison shows a reasonable consistency between the estimates generated by these two models in low chlorophyll concentration areas, but the water leaving radiance derived by OCITRAN-1 is significantly greater than that derived by SeaDAS, especially when the chlorophyll concentration is higher than 2.0 mg/m³. Therefore, the aerosol effect correction of OCITRAN-1 is most suitably applied in ocean areas of low chlorophyll concentration.