Study On Brightness Temperature Simulation Of Lunar Surface Based On DEM

The thickness of lunar regolith is one of the four scientific objectives, and it isindispensable to develop a precise microwave radiative brightness temperature (TB)model to retrieve the thickness of lunar regolith. Firstly, this paper introduces theevolution of the lunar surface microwave transfer model in detail, and discusses severalimportant factors, such as terrain, neighbor scatter and micro-sacle roughness. Then, thispaper integrates DEM into existing microwave transfer model. What’s more, the newmodel can simulate TB of any place at any time in theory, which is the most significantdifference between the new model and former model.In order to generate DEM by CCD images, this paper introduces the common processof the generation of DEM based on three-line CCD images, and takes Hercules crafter asan instance, finding that gross error thread and gross error cluster exists in the result. Thecharacteristic of these two gross errors is discussed. Local affine transformation isproposed to restrain the gross error cluster caused by mismatch which is mainly inducedby gray-scale saturation, and classic intersection algorithm is replaced by pyramidalgorithm to decrease the influence of the error of control points on DEM and thus restrainthe gross error. At last, it is found that simulated effective solar irradiance image based oncorrected DEM can efficiently reflect contour of DEM, and some conclusion about grosserror thread is deduced.After obtaining DEM, effective solar irradiance can be calculated by terrain reviseand shadowing effect. It’s proved that terrain revise can really bring local irradianceenhancement and local irradiance attenuation, and shadow area accords with CCD images.After the iterative stable condition of thermal conduction formulation is analysed, adaptivestratification method is proposed to solve the problem that existing thermal conductionformulation can’t apply to random thickness of lunar regolish.After computing the temperature of all the grids, normalizd simulated TB is obtainedafter normalizd metho based on antenna pattern formulation is adopted, which can makesimulated data approach observational data, and simulated TB is with the same time andthe same covering area as observational data is obtained. Aim at the phenomenon thatobservational TB of Hercules crafter at daytime and nighttime both present largefluctuations, TB of Hercules crafter at the two times is simulated, and TB of flat area at thetwo times is simulated. The result shows that the trend of simulated TB agrees withobservational TB’s, proving that terrain can have a significant influence on TB. What’smore, this paper analyses emission angle and antenna pattern formulation, and some conclusion is deduced.