基于EOS/MODIS 的云雾光学厚度和有效粒子半径反演研究

使用SBDART 辐射传输模式模拟EOS/MODIS 可见光和近ö短波红外通道的光学特性, 分析了使用这些通道进行云雾光学厚度和有效粒子半径反演的可行性, 建立了不同条件下的正演模拟辐射数据库, 在此基础上反演云雾光学厚度和有效粒子半径。敏感性研究表明, 不同波长的近/短波红外波段反射率对不同高度上的粒子敏感, 使用不同通道组合反演所得的有效粒子半径反映了云层不同高度上的粒子尺度特征。结合卫星数据和常规资料做了实例分析, 分析结果表明, 反演结果具有合理性。

Remoting Sensing Clouds Optical Thickness and Effective Radius Using MODIS MULTSPECTRAL Data

Cloud microphysical property has great impact on their optical character and the radiation budget of the earth-atmo sphere system. In this paper, the spectrum characteristics of MODIS VIS and NIR/SIR channels are simulated with SBDART radiat ive transfer model, the simulated result shows MODIS VIS channel is sensitive to the optical thickness while NIR/SIR channels are sensitive to the effective radius of cloud. An algorithm is presented for retrieving the optical thickness and effective radius, the database of such channels’ reflectivity is created and used to retrieve. In addition, an instance is presented to approved the rationality of themethod. The theoretical sensitivity study, which is about the distribution of retrieved effective radius changing with the height, demonstrates that retrieving effective radius using different channels represent different particle scale characteristic in different height of the cloud, respectively. For in stance, channel 20 (3. 75 Lm) is sensitive to the particles at the top of cloud and, channel 6 (1. 64 Lm )mainly represent the middle particles’ scale characteristic, and channel 7 (2. 13 Lm ) is sensitive to the particles between channel 20 and channel 6.