The retrieval of sea fog characteristic from NOAA17 AVHRR3 data

Abstract

Sea fog is considered as a cloud cling the surface and reducing visibility to 1km or less in this paper. For fog or cloud, simulating results show that the reflected radiance in the visible spectral region depends mainly on the fog/cloud optical thickness and the reflected radiance in near-infrared spectral region depends mainly on the fog/cloud particle effective radius. Owing to this, by combining the visible and the near-infrared reflected solar radiation and using the lookup table about the reflectance function for various values of optical thickness and effective particle radius created by the Streamer radiative transfer model, a retrieval algorithm was developed to determine the optical thickness and the effective particle radius of sea fog simultaneously from NOAA17 AVHRR3 data. According to the definition of visibility and liquid water content, the relations and formulas of fog properties (optical thickness, particle effective radius, liquid water content and visibility) are described. Lastly, the other two properties, liquid water content and visibility on known sea fog regions are also estimated. It is those four sea fog properties retrieved from satellite observations that can offer the condition for analyzing and forecasting the time of fog clearance in future.