本文選題：微波遙感　切入點(diǎn)：輻射與散射　出處：《華中科技大學(xué)》2012年博士論文　論文類型：學(xué)位論文

【摘要】：上世紀(jì)六十年代開始,人類通過(guò)各種方式展開了對(duì)月球的探測(cè),希望通過(guò)研究月球地形、地貌、內(nèi)部結(jié)構(gòu)和物質(zhì)組成等信息,了解月球及其它星球的形成和演化歷史,并帶動(dòng)一系列相關(guān)學(xué)科的創(chuàng)新和發(fā)展。在探月過(guò)程中,微波遙感技術(shù)是探測(cè)全月球表層土壤內(nèi)部結(jié)構(gòu)和物質(zhì)組成的重要手段。由于對(duì)月探測(cè)的成果無(wú)法像對(duì)地遙感那樣直接取樣驗(yàn)證,因此探測(cè)結(jié)果的正確性依賴于對(duì)遙感數(shù)據(jù)的認(rèn)識(shí)、處理和分析。在這個(gè)過(guò)程中,月壤模型的建立和分析尤為關(guān)鍵,也成為探月中的重要研究方向。 雖然月球距地球十分遙遠(yuǎn),但微波輻射理論和電磁散射理論為月壤輻射與散射特性的研究提供了強(qiáng)有力的理論基礎(chǔ),而計(jì)算機(jī)性能的提高以及高性能、集群式工作站的出現(xiàn)更是為定量計(jì)算月表輻射亮溫和散射系數(shù)等特性提供了硬件基礎(chǔ)。通過(guò)這種數(shù)值計(jì)算的方式,可以有效地研究不同月壤模型的輻射與散射特性,并在此基礎(chǔ)上提出月表探測(cè)方案及月壤相關(guān)參數(shù)的反演方法。將理論分析結(jié)果與實(shí)測(cè)數(shù)據(jù)對(duì)比,有利于正確闡釋遙感數(shù)據(jù)中的月壤特征,認(rèn)識(shí)月壤內(nèi)部的真實(shí)結(jié)構(gòu)。因此,本文圍繞月表輻射和散射的數(shù)值計(jì)算展開了相關(guān)研究工作,主要包括： 首先對(duì)微波輻射測(cè)量和電磁散射計(jì)算的基礎(chǔ)理論進(jìn)行了介紹,在總結(jié)月壤相關(guān)研究(如月表粗糙度、月壤溫度剖面、月壤模型等)的基礎(chǔ)上,結(jié)合月壤次表面結(jié)構(gòu)和水冰探測(cè)的需要,提出了包含月表粗糙性的多層物理模型,為研究粗糙月表的輻射與散射特性打下基礎(chǔ)。同時(shí),為減少數(shù)值計(jì)算的復(fù)雜度,采用高斯隨機(jī)粗糙面,研究了一維粗糙面和二維粗糙面間的差異。研究結(jié)果表明,當(dāng)二維粗糙面在兩個(gè)維度上具有相同的粗糙度時(shí),可以采用一維粗糙面進(jìn)行模擬仿真,有利于降低數(shù)值計(jì)算的復(fù)雜度。 其次,基于多層月壤物理模型,研究了月表輻射亮溫和散射特性的計(jì)算方法。對(duì)于輻射亮溫,提出了微波輻射傳輸理論與矩量法相結(jié)合的混合方法,用于研究粗糙月表的輻射亮溫,并對(duì)方法的有效性進(jìn)行了驗(yàn)證。研究結(jié)果表明：月表粗糙度會(huì)對(duì)輻射亮溫產(chǎn)生影響,且與輻射計(jì)極化狀態(tài)和觀測(cè)角有密切關(guān)系；通過(guò)調(diào)整輻射計(jì)觀測(cè)角,在垂直極化狀態(tài)下能夠?qū)⒋植诙鹊挠绊懡抵凛^低水平,從而利于月壤參數(shù)的反演。對(duì)于月壤散射特性,研究了次表面回波與表面回波的相干性,并在此基礎(chǔ)上提出了采用步進(jìn)頻率雷達(dá)進(jìn)行次表面結(jié)構(gòu)探測(cè)的方案。結(jié)合矩量法計(jì)算結(jié)果,對(duì)探測(cè)方案的性能進(jìn)行了討論,結(jié)果表明：步進(jìn)頻率信號(hào)能提供更豐富的散射信息,使該方案在月表粗糙度較大情況下,仍然能夠?qū)Υ伪砻娼Y(jié)構(gòu)進(jìn)行探測(cè),但需要分層面上下媒質(zhì)的介電常數(shù)差異足夠大。在數(shù)值計(jì)算方法研究的基礎(chǔ)上,對(duì)月壤中可能存在的水冰帶來(lái)的影響進(jìn)行了分析。當(dāng)月壤中含有水冰時(shí),會(huì)引起發(fā)射率增加、輻射亮溫升高等現(xiàn)象,但單一的探測(cè)手段不足以對(duì)水冰的存在及含量進(jìn)行判斷,需借助多遙感設(shè)備進(jìn)行復(fù)合探測(cè),并對(duì)月壤參數(shù)進(jìn)行聯(lián)合反演。 再次,為了配合月表散射特性計(jì)算,針對(duì)月壤模型的大尺度、多層粗糙面等結(jié)構(gòu)特點(diǎn),提出了廣義帶狀矩陣迭代(GBMIA)算法,并用矩量法對(duì)新算法的精確度進(jìn)行了檢驗(yàn)。結(jié)果表明：GBMIA既降低了存儲(chǔ)量,又節(jié)省了計(jì)算時(shí)間,并且不會(huì)對(duì)計(jì)算結(jié)果帶來(lái)太大誤差,適合研究月表散射特性。 最后,研究了系統(tǒng)空間分辨率的增強(qiáng)算法。采用信號(hào)處理方式等效于減小天線波束覆蓋范圍,從而降低月壤模型的計(jì)算規(guī)模。仿真和實(shí)驗(yàn)結(jié)果表明,本文通過(guò)改進(jìn)高頻提升法,使系統(tǒng)空間分辨率進(jìn)一步提高,而且反演結(jié)果更準(zhǔn)確。
[Abstract]:In the beginning of 60s, humanity has launched the lunar exploration through a variety of ways, hope through the study of lunar topography, landform, internal structure and material composition information, understand the formation of the moon and other planets and the evolution history, and promote the innovation and development of a series of related disciplines. In lunar exploration process, microwave remote sensing technology is an important means to detect the whole lunar surface soil internal structure and material composition. Because the moon exploration results not as verification of remote sensing as a direct sampling, so the correctness of the results depends on the knowledge of remote sensing data, processing and analysis. In this process, the lunar regolith model construction and analysis has become particularly critical, an important research direction of lunar exploration.
Although the moon is very far from the earth, but provides a strong theoretical basis on the theory of microwave radiation and electromagnetic scattering theory of lunar radiation and scattering properties, and the improvement of computer performance and high performance, appearance of the cluster workstation is to provide a hardware based shot brightness temperature and scattering coefficient characteristics for the quantitative calculation of the lunar radiation. Through the numerical calculation, the radiation and scattering characteristics can effectively study different lunar soil model, based on the inversion method of lunar regolith scheme and related parameters. The comparison between theoretical analysis results and the measured data are lunar features for the correct interpretation of remote sensing data, know the real structure of July the soil inside. Therefore, the calculation carried out the relevant research work of this paper focuses on numerical lunar radiation and scattering, including:
The basic theory of microwave radiation first measurement and calculation of the electromagnetic scattering are introduced in the related research summary of lunar regolith (surface roughness, such as lunar regolith model of temperature profile, etc.) on the basis of combining with the need of lunar subsurface structure and detection of water ice, which contains the physical model of surface roughness of multilayer and lay the foundation for the radiation and scattering characteristics of rough surface. At the same time, to reduce the complexity of numerical calculations, the Gauss studies the one-dimensional random rough surface, rough surface and rough surface. The difference between the results of the study show that, when the two dimensional rough surface in two dimensions with the same roughness. The one-dimensional rough surface is simulated. To reduce the complexity of calculation.
Secondly, based on the physical model of multilayer regolith, calculation method of the surface radiation brightness temperature and scattering characteristics. The brightness temperature, proposes a hybrid method combining microwave radiative transfer theory and the method of moments, for the study of rough surface radiation brightness temperature, and the effectiveness of the method was verified. The results of the study show that the surface roughness will affect the brightness temperature, and radiometer polarization state and observation angle are closely related; perspective angle by adjusting the radiation, the effect of roughness can be reduced to a lower level in the vertical polarization, thus contributing to the inversion of lunar regolith parameters. The scattering characteristics of lunar regolith, research the coherence time surface echo and surface echo, and on the basis of the step frequency radar surface structure detection scheme. The calculation results with the method of moments, the detection scheme of can The discussion shows that the stepped frequency signals can provide more information of scattering, the scheme on the lunar surface roughness is larger, can still detect the surface structure, but need to face layered medium dielectric constant difference is large enough. Based on the numerical method research, influence water ice may exist in lunar regolith have been analyzed. The soil containing water ice, will cause the emission rate increased, the brightness temperature rising phenomenon, but a single means is not enough to exist and content on the ice to judge, to compound detection by means of multi remote sensing equipment, and the lunar regolith parameters were combined inversion.
Again, in order to cope with the surface scattering characteristics for large scale calculation, regolith model, multilayer rough surface structure characteristic, proposed a generalized banded matrix iterative (GBMIA) algorithm, and test the accuracy of the new algorithm using the moment method. The results show that GBMIA not only reduces the amount of storage, but also saves computing time not too much, and the error of calculation results, suitable for surface scattering characteristics research.
Finally, the system spatial resolution enhancement algorithm. By using the signal processing method is equivalent to reduce the antenna beam coverage, so as to reduce the calculation scale of lunar soil model. The simulation and experimental results show that the improved high-frequency lifting method, the spatial resolution of the system further improved, and the accuracy of the inversion results.

【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2012
【分類號(hào)】：P184

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本文編號(hào)：1583431