Volume Yunguang Scattering Characteristics Research And Reflectivity Inversion

The cirrus cloud is composed of various shapes of ice particles. Because of its important influence on atmospheric radiation budget, remote sensing detection, photoelectric instrument early warning and target recognition, it has been a hot topic in the field of atmospheric optics to analyze the scattered radiation characteristics as well as the remote sensing and retrieval of the cirrus parameters. This dissertation focuses on the optical scattering properties, the remote sensing and retrieval of the cirrus reflectance and some other issues, providing a further analysis on the optical scattering properties of the single nonspherical ice crystal and the cirrus average optical scattering properties, demonstrating the theories such as the retrieval algorithm of the cirrus reflectance, computing the scattering characteristics and retrieving the reflectivity of the cirrus. The main contents were as follows:1. The hierarchical data format（HDF） and the pre-treatment process of the data generated by the MODIS（Moderate Resolution Imaging Spectroradiometer） were analyzed in detail. The single scattering characteristic of the individual ice particle was studied in the Van De Hulst extraordinary diffraction method, and the optical scattering properties of the single ice particle at1.375μm and0.55μm were calculated with this approach.2. The additivity principle of the synthetic scattering wave intensity and the definition of the cirrus average scattering properties were introduced. Based on the definition of the cirrus average scattering properties, the cirrus average scattering property parameters were calculated, which included the average asymmetry factor, the average absorption efficiency factor and the average extinction efficiency factor. The relationship between the effective dimension and the scattering properties of the cirrus at2.75μm,0.55μm and1.375μm were discussed.3. The MODIS data radiometric calibration process and the export procedure of the data derived from radiometric correction were analyzed in the remote sensing information processing software ENVI. The three typical detection algorithms of the cirrus and high cloud were studied. The clouds were detected as an instance by remotely sensing the data and images with the MODIS as well. These calculation results show that the detection consequences of the cloud were affected by the altitude, ice and snow distribution, surface type, climate models and some other factors. And compare with MOD35₂L cloud mask information indicated that the detection consequences were more reasonable.4. The earth-atmospheric system model and the retrieval algorithm of the cirrus reflectance were investigated in detail. A simplified retrieval algorithm was proposed based on the earth-atmospheric system model. The cirrus reflectivity of visible light band was retrieved with the radiometric correction data of the MODIS₁B, and the realization process of the algorithm was described in detail. The results show that the cirrus reflectance was less than0.4392for most of the pixels in the corresponding sixteenth pieces of subgraph. And by analyzing the realization process of the algorithm, six possible uncertainties were obtained.