Surface visibility retrieval with observations from the medium resolution spectral imager (MERSI) onboard the FY-3A meteorological satellite.

Satellites provide an opportunity of obtaining spatially continuous visibility data. This paper develops an algorithm that retrieves visibility from the Medium Resolution Spectral Imager (MERSI) onboard the FY-3A satellite. The visibility retrieval algorithm consists of two basic steps. First, aerosol optical depth (AOD) is retrieved with MERSI observations at the 2.1 μm, 0.47 μm, and 0.65 μm channels based on look-up-table approach. Second, visibility is calculated with the relationship between visibility and aerosol optical thickness and aerosol scale height, which can be derived from the Koschmieder equation. Two sets of aerosol scale heights are tested, one based on climatic statistics and the other on mixing layer height forecasts. Results show that the distribution pattern and the high and low centers of retrieved visibility match well with that of the surface observations. Compared to the results derived based on climatologically aerosol scale heights, the ones based on mixing layer heights deviate less from surface observations. [ABSTRACT FROM AUTHOR]