FY-1C/1D全球海上气溶胶业务反演算法研究

Development of aerosol retrieval algorithm over global ocean using FY-1C/1D data

介绍了基于FY-1C/1D气象卫星数据进行全球海洋气溶胶反演的业务算法,主要论述了海上气溶胶反演的单通道算法基本原理.该算法的核心内容是建立气溶胶光学厚度查算表,该查算表基于6S辐射传输模式,在假定气溶胶模式条件下,卫星的表观反射率是卫星观测几何(太阳卫星角)和气溶胶光学厚度函数,最终由卫星观测表观反射率反演出气溶胶光学厚度.业务反演过程中还考虑到数据质量检验、云检测处理和太阳耀斑区去除等.利用该算法对FY-1C卫星自2001年起的部分资料进行反演试验,并在FY-1D卫星发射后投入业务应用,自2002年8月开始能实时得到每天和每月的全球气溶胶光学厚度产品.从两颗卫星两年多连续反演结果分析可以非常清晰地发现全球气溶胶主要排放源地和全球海上气溶胶分布的季节变化,与国外卫星反演结果十分接近.

An operational algorithm of aerosol retrieval is described based on the FY-1C/1D data over global oceans. A single-channel algorithm is proposed. A look-up table（LUT） for aerosol retrieval is established using a state-of-art radiative transfer model 6S（second simulation of the satellite signal in the solar spectrum）. The LUT shows that the apparent reflectance is the function of observation geometry （solar and viewing angles） and aerosol optical depth. Eventually, the LUT is used to retrieve the aerosol optical depth by the observed apparent reflectance. The data quality checking, cloud mask and sun-glint discrimination are considered during the operation processing. This algorithm has been used to test aerosol retrieval for FY-1C data since 2001 and introduced into the FY-1D operation performing including daily and monthly mean composite aerosol product since 2002. Analysis of the result reveals that all main aerosol sources are located over the global oceans and also reveals season variety in the globally averaged aerosol optical depth. They are nearly close to results of other similar foreign sensors in spatial distribution and numeral quantity.