【摘要】：月球表面是粗糙面，既存在地形起伏的大尺度粗糙度，也存在微小尺度的粗糙度。目前國內(nèi)外關(guān)于微尺度粗糙月面對(duì)月壤微波輻射亮溫的影響的研究都基于幾何光學(xué)方法，但幾何光學(xué)只適用于探測波長比散射表面的曲率半徑小得多的情況。幾何光學(xué)模型的一個(gè)缺陷是缺乏亮溫改變對(duì)探測波長的顯式依賴關(guān)系。在一些地形比較平坦的地區(qū)如月海地區(qū)，月壤表面可以視為微粗糙表面。本文中，月海地區(qū)的月壤被視為多層煤質(zhì)，表面為微粗糙面，下面各層界面為平面。溫度剖面由熱傳導(dǎo)方程解出。本文采用非相關(guān)方法計(jì)算媒質(zhì)的發(fā)射率。采用二階微擾法計(jì)算頂層粗糙面對(duì)亮溫的影響。然后基于所建立的亮溫模型，本文仿真分析了不同微粗糙度條件下的Apollo12地區(qū)亮溫。結(jié)果表明，，月面微粗糙度將會(huì)增加或降低月表的微波亮溫，這取決于微粗糙度、入射角、頻率、極化的情況。對(duì)CE-1和CE-2微波輻射計(jì)而言，其入射角為0°，微粗糙度將會(huì)增大月壤亮溫。 另一方面，國內(nèi)外關(guān)于大尺度粗糙度對(duì)月壤輻射亮溫影響的研究比較少。為考慮其影響，本文利用月球軌道激光測高儀（Lunar Orbiter Laser Altimeter,LOLA）的全月高程數(shù)據(jù)，將CE-2衛(wèi)星探測時(shí)的天線月面足印內(nèi)的地形視作一個(gè)本地傾斜基準(zhǔn)面和該基準(zhǔn)面上二維粗糙度的疊加，根據(jù)傾斜、遮蔽等特點(diǎn)推導(dǎo)有效太陽輻照度的計(jì)算公式，然后代入熱傳導(dǎo)方程，通過改進(jìn)其數(shù)值解法，求解出更加準(zhǔn)確的月壤溫度剖面，最后將溫度剖面代入分層亮溫模型，結(jié)合月壤分層亮溫模型計(jì)算了三個(gè)典型月陸地區(qū)，Apollo15、Aristoteles撞擊坑、Hercules撞擊坑地區(qū)的月壤亮溫，最終與CE-2實(shí)測亮溫進(jìn)行對(duì)比，從而分析地形起伏的大尺度粗糙度對(duì)月壤亮溫的影響。結(jié)果表明，大尺度粗糙面模擬亮溫隨緯度的變化規(guī)律與實(shí)測亮溫保持一致，這與平面模型相比有很大的改善，從而說明了在計(jì)算有地形起伏的亮溫時(shí)必須考慮大尺度粗糙度的影響。
[Abstract]:The surface of the moon is a rough surface, which has not only the roughness of large scale but also the roughness of small scale. At present, the research on the effect of micro-scale rough moon on the bright temperature of lunar soil microwave radiation is based on geometric optics method, but geometric optics is only suitable for the case where the detection wavelength is much smaller than the curvature radius of the scattering surface. One defect of the geometric optical model is the lack of explicit dependence of the brightness temperature on the detection wavelength. In some flat terrain areas such as the Moon Sea, the surface of lunar soil can be regarded as a slightly rough surface. In this paper, the lunar soil in the Yuehai area is regarded as a multi-layer coal with a surface of slightly rough surface and a plane at the bottom of each layer. The temperature profile is solved by the heat conduction equation. In this paper, the emissivity of the medium is calculated by non-correlation method. The second order perturbation method is used to calculate the effect of the top roughness on the brightness temperature. Then, based on the established bright temperature model, the brightness temperature in Apollo12 region under different micro-roughness conditions is simulated and analyzed. The results show that the surface roughness will increase or decrease the microwave brightness temperature, which depends on the micro-roughness, incidence angle, frequency and polarization. For CE-1 and CE-2 microwave radiometers, the incidence angle is 0 擄, and the micro-roughness will increase the bright temperature of lunar soil. On the other hand, there are few studies on the effect of large-scale roughness on radiative bright temperature of lunar soil at home and abroad. In order to consider its influence, the full moon elevation data of lunar orbit laser altimeter (Lunar Orbiter Laser Altimeter,LOLA) are used in this paper. The topography in the footprint of the lunar surface of the antenna during the CE-2 satellite detection is regarded as a local tilt datum and the superposition of the two-dimensional roughness on the base level. The effective solar irradiance calculation formula is derived according to the characteristics of tilt and obscuration. Then the heat conduction equation is introduced, and a more accurate temperature profile of lunar soil is solved by improving its numerical solution. Finally, the temperature profile is added to the stratified bright temperature model, and the three typical lunar land regions, Apollo15, are calculated in combination with the stratified bright temperature model of lunar soil. The light temperature of lunar soil in Aristoteles crater and Hercules crater area is finally compared with the measured light temperature of CE-2, so as to analyze the influence of the large scale roughness of topographic fluctuation on the light temperature of lunar soil. The results show that the variation of brightness temperature with latitude in large scale rough surface simulation is consistent with the measured brightness temperature, which is greatly improved compared with the plane model. It shows that the influence of large scale roughness must be taken into account in calculating the bright temperature with topographic fluctuation.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：P184

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