本文關(guān)鍵詞：星載L波段一維綜合孔徑輻射計海洋鹽度探測任務(wù)仿真　出處：《中國科學院國家空間科學中心》2016年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 一維綜合孔徑輻射計 系統(tǒng)仿真 G矩陣 太陽干擾 月亮干擾 銀河干擾

【摘要】：全球大約有71%的面積被海洋覆蓋,海表面鹽度是研究全球天氣預(yù)報及氣候變化的重要示蹤因子,它的分布及變化對研究海洋氣候系統(tǒng)起著關(guān)鍵性作用。但是海洋鹽度遙感的發(fā)展速度遠遠落后于對其應(yīng)用的需要。相比于采樣船等現(xiàn)場測量鹽度的方法,太空遙感更能實現(xiàn)大面積、長時間的觀測,這對于工程建設(shè)、資源開發(fā)以及科學研究等領(lǐng)域都具有至關(guān)重要的作用。在這樣的背景下,中國科學院國家空間科學中心提出了主被動聯(lián)合探測鹽度計劃,用于觀測全球土壤濕度和海表面鹽度。利用高靈敏度、高穩(wěn)定度的L波段推帚式(push-broom)輻射計,能夠?qū)θ蚝１砻纣}度分布進行高精度觀測;利用共用反射面天線的L波段散射計,同步獲取海面粗糙度信息,改進鹽度測量精度,其中,輻射計是整個系統(tǒng)中最重要的部分。輻射計為綜合孔徑體制,天線陣列有8個天線,排成一維陣列,工作頻率為1.4135GHz。與歐空局SMOS衛(wèi)星的二維綜合孔徑輻射計系統(tǒng)相比,采用一維方案可以降低系統(tǒng)的復(fù)雜度。與采用真實孔徑的美國Aquarius衛(wèi)星相比,一維綜合孔徑可以實現(xiàn)更好的空間分辨率及刈幅指標。本文基于Matlab平臺搭架一維綜合孔徑輻射計仿真系統(tǒng),根據(jù)星載一維綜合孔徑輻射計的系統(tǒng)組成結(jié)構(gòu)及工作過程建立模型,主要實現(xiàn)目標場景生成、輻射計系統(tǒng)仿真、亮溫重構(gòu)的功能。目標場景生成模塊主要模擬衛(wèi)星獲得觀測亮溫的過程,即輸入海表面溫度、海表面鹽度、風速等數(shù)據(jù),結(jié)合軌道參數(shù),輸出衛(wèi)星在任意一個軌道位置所觀測到的視場亮溫圖像。輻射計系統(tǒng)仿真模塊模擬的是綜合孔徑輻射計空間頻率域采樣過程,主要根據(jù)綜合孔徑輻射計的測量原理并結(jié)合一維綜合孔徑輻射計天線陣列排布,對目標場景生成模塊的觀測亮溫進行頻域采樣,生成可見度函數(shù)。亮溫重構(gòu)模塊根據(jù)一維天線陣列的特點,提出一種高精度的亮溫重構(gòu)算法,將可見度函數(shù)轉(zhuǎn)化為空間域的亮溫,滿足設(shè)計需求。利用一維綜合孔徑輻射計仿真系統(tǒng),評估外部誤差源,包括銀河、月亮、太陽直射對亮溫的影響。首先根據(jù)天文知識并結(jié)合軌道參數(shù),對外部誤差源在觀測視場內(nèi)的位置進行建模;然后根據(jù)外部誤差源亮溫及其在視場中的位置變化,仿真得到銀河、月亮、太陽直射對系統(tǒng)X、Y極化亮溫影響的年際變化規(guī)律。本文所做的工作為后續(xù)綜合孔徑輻射計系統(tǒng)的進一步優(yōu)化和設(shè)計提供仿真平臺,也為接下來海表面鹽度探測的硬件系統(tǒng)指標設(shè)計以及應(yīng)用反演提供參考依據(jù)。
[Abstract]:About 71% of the world is covered by the ocean. Sea surface salinity is an important tracer for global weather forecasting and climate change. Its distribution and variation play a key role in the study of marine climate system, but the development speed of marine salinity remote sensing is far behind the need of its application. Space remote sensing can achieve large area, long time observation, which is very important for engineering construction, resource development and scientific research. In this context. The National Space Science Center of the Chinese Academy of Sciences has proposed a joint active and passive salinity detection program for the observation of global soil moisture and sea surface salinity with high sensitivity. The L-band push-broom radiometer with high stability can accurately observe the salinity distribution of the global sea surface. The L-band scatterometer of common reflector antenna is used to acquire the sea surface roughness information synchronously and improve the measuring accuracy of salinity. The radiometer is the most important part of the whole system. The radiometer is a synthetic aperture system. The antenna array consists of eight antennas arranged in a one-dimensional array operating at a frequency of 1.4135 GHz compared with the two-dimensional synthetic aperture radiometer system of the ESA SMOS satellite. One dimensional scheme can reduce the complexity of the system, compared with the American Aquarius satellite with real aperture. One-dimensional synthetic aperture can achieve better spatial resolution and cut index. This paper builds a one-dimensional synthetic aperture radiometer simulation system based on Matlab platform. According to the system structure and working process of spaceborne one-dimensional synthetic aperture radiometer, the model is established, which mainly realizes the target scene generation and radiometer system simulation. The target scene generation module mainly simulates the process of satellite obtaining observed brightness temperature, that is, input sea surface temperature, sea surface salinity, wind speed and other data, combined with orbital parameters. The radiometer system simulation module simulates the sampling process of synthetic aperture radiometer in spatial frequency domain. According to the measurement principle of synthetic aperture radiometer and the arrangement of antenna array of one-dimensional synthetic aperture radiometer, the observation brightness temperature of target scene generation module is sampled in frequency domain. According to the characteristics of one-dimensional antenna array, a high-precision brightness temperature reconstruction algorithm is proposed to transform the visibility function into the bright temperature in spatial domain. To meet the needs of the design. Using a one-dimensional synthetic aperture radiometer simulation system to evaluate the external error sources, including the Milky way, the moon, the direct solar radiation on the bright temperature. First, according to astronomical knowledge and combined with orbital parameters. The position of the external error source in the field of view is modeled. Then according to the light temperature of the external error source and its position change in the field of view, the system X is simulated. The work done in this paper provides a simulation platform for the further optimization and design of the integrated aperture radiometer system. It also provides reference for hardware system index design and application inversion of sea surface salinity detection.
【學位授予單位】：中國科學院國家空間科學中心
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：P715.7

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