使用6S模型由GMS5卫星资料反演陆地大气气溶胶光学厚度

Using 6S Model to Retrieve Aerosol Optical Depth above Land from GMS5 Satellite Data

采用每日08、11、14、17时(北京时)地面气象观测资料、卫星资料,应用6S辐射传输模型(second simulation of satellite signal in the solar spectrum)建立一幅晴空条件下4个时次的大气辐射参数背景底图。利用辐射传输理论,在辐射参数(背景底图上)与大气气溶胶光学厚度(aerosol op-tical depth,AOD;任意一天与背景底图同时次)之间建立了闭合一元非线性方程,求解方程得到晴空条件下陆地大气气溶胶光学厚度。选用一月内的GMS5-VISSR可见光通道资料,按上述方法得到选定时间段内的每日08、11、14和17时北京气象观测站位置处的550 nm晴空大气气溶胶光学厚度。反演得到的晴空AOD值可以反映1个月内气溶胶光学厚度的日变化规律。另外,在中国大陆范围内划定反演试验区域,选择试验区域内的气象站所在位置为反演点,制作底图,并求算2002年5月1—17日、7月13日—8月14日站点位置的AOD。由站点值插值到整个反演试验区域内,所得结果反映出任意时次反演试验区内的气溶胶空间分布情况。

Using satellite data and routine meteorological observation data as well as the second simulation of satellite signal in the solar spectrum, the background figures of atmospheric radiation parameters for 08：00,11：00,14：00,17 ： 00 BST of given month, could be constructed, which is composed of the apparent reflectance under the cloudless and dry air condition. Because of the difference in the zenith and azimuth, the hour by hour background figures should be created. Thus some atmospheric parameters of the background figures are possible to be calculated by utilizing the second simulation of satellite signal in the solar spectrum （6S）. Applying these parameters to the radiation transfer equation,the atmpspheric optical depth（AOD） at any time is gained. When validating the above idea, four groups of optical depth at 550 nm above Beijing meteorological station derived from the GMS5 VISSR visible albedo data are calculated at 08.00,11 ： 00,14-00,17 ： 00BST, respectively. When comparing the values obtained by the retrieval method in this article and from the lidar vertical attenuation data, a good agreement could been seen. After defining a test area,AOD values over dozens of meteorological stations within the area in the periods of 1st to 17th May and 13th July to 14th August 2002 are retrieved using the above means. Then the grid values of the retrieved AOD over the whole retrieval test area are gained using a spatial interpolation method. The results show the retrieved AOD is able to reveal the distribution feature of aerosols.