Cirrus Scene Simulation And Experiment In Strong Absorption Band

In the infrared earth observation scene,the atmospheric top entrance pupil radiance of cirrus is similar to that of the target,and it has a similar gray value to the target in the infrared image,so the existence of cirrus will interfere with the detection and tracking of targets,and the research on cirrus scene simulation is of great significance.The cirrus albedo is crucial since the reflected radiation of cirrus is an important component of cirrus cloud radiance.In addition,radiative transfer is affected by atmospheric absorption and scattering.Therefore,based on the radiative transfer equation,this thesis proposes a simulation model of cirrus scene with strong absorption band based on the virtual underlying surface with the data of MODIS,FY3 C and FY3 D.The main research contents of this thesis are as follows:（1）The theory of optical radiative transfer in cloud-free atmosphere is studied.In this thesis,the absorption and scattering effects of atmospheric particles are researched,and the atmospheric optical radiative transfer modeling is realized for single-layer medium and multi-layer medium.This part is the core theory of this thesis.The atmospheric top entrance pupil radiance of each pixel in the scene is calculated by the radiation transfer equation,and then converted into an infrared image to obtain the final simulation result.（2）An atmospheric profile generation model is proposed.Due to the low time resolution of the atmospheric profiles provided by MODTRAN,the relevant data of FY3 D is used to obtain the atmospheric profiles of different latitude bands each month,which provides data support for the simulation of earth-atmosphere background without clouds and cirrus scenes in the strong absorption band.（3）The simulation of earth-atmosphere background without clouds in the strong absorption band is realized.For a earth-atmosphere background without clouds,the albedo of different land cover types is obtained first,and then the radiative transfer equation is solved to complete the simulation of earth-atmosphere background without clouds in the strong absorption band which provides services for the background part of the simulation of the cirrus scene in the following.（4）The optical properties of cirrus are studied.In this thesis,the DISORT model is used to solve the albedo of cirrus by combining parameters such as solar zenith angle,optical depth,effective scale,single scattering albedo,and asymmetric factor.Cirrus albedo is an important parameter for the calculation of cirrus reflected radiance.（5）A simulation model of cirrus scene with strong absorption band based on virtual underlying surface is proposed.In the model,cirrus is regarded as the virtual surface,and the radiation penetrating the cirrus is ignored.Simulation results show that the average radiance of cirrus is much larger than the average radiance of the ground surface in the2.7（25）2.8μm band,which achieves a good simulation effect.