星载L波段一维综合孔径辐射计海洋盐度探测任务仿真

发布时间：2018-01-02 09:39

本文关键词：星载L波段一维综合孔径辐射计海洋盐度探测任务仿真　出处：《中国科学院国家空间科学中心》2016年硕士论文　论文类型：学位论文

【摘要】：全球大约有71%的面积被海洋覆盖,海表面盐度是研究全球天气预报及气候变化的重要示踪因子,它的分布及变化对研究海洋气候系统起着关键性作用。但是海洋盐度遥感的发展速度远远落后于对其应用的需要。相比于采样船等现场测量盐度的方法,太空遥感更能实现大面积、长时间的观测,这对于工程建设、资源开发以及科学研究等领域都具有至关重要的作用。在这样的背景下,中国科学院国家空间科学中心提出了主被动联合探测盐度计划,用于观测全球土壤湿度和海表面盐度。利用高灵敏度、高稳定度的L波段推帚式(push-broom)辐射计,能够对全球海表面盐度分布进行高精度观测;利用共用反射面天线的L波段散射计,同步获取海面粗糙度信息,改进盐度测量精度,其中,辐射计是整个系统中最重要的部分。辐射计为综合孔径体制,天线阵列有8个天线,排成一维阵列,工作频率为1.4135GHz。与欧空局SMOS卫星的二维综合孔径辐射计系统相比,采用一维方案可以降低系统的复杂度。与采用真实孔径的美国Aquarius卫星相比,一维综合孔径可以实现更好的空间分辨率及刈幅指标。本文基于Matlab平台搭架一维综合孔径辐射计仿真系统,根据星载一维综合孔径辐射计的系统组成结构及工作过程建立模型,主要实现目标场景生成、辐射计系统仿真、亮温重构的功能。目标场景生成模块主要模拟卫星获得观测亮温的过程,即输入海表面温度、海表面盐度、风速等数据,结合轨道参数,输出卫星在任意一个轨道位置所观测到的视场亮温图像。辐射计系统仿真模块模拟的是综合孔径辐射计空间频率域采样过程,主要根据综合孔径辐射计的测量原理并结合一维综合孔径辐射计天线阵列排布,对目标场景生成模块的观测亮温进行频域采样,生成可见度函数。亮温重构模块根据一维天线阵列的特点,提出一种高精度的亮温重构算法,将可见度函数转化为空间域的亮温,满足设计需求。利用一维综合孔径辐射计仿真系统,评估外部误差源,包括银河、月亮、太阳直射对亮温的影响。首先根据天文知识并结合轨道参数,对外部误差源在观测视场内的位置进行建模;然后根据外部误差源亮温及其在视场中的位置变化,仿真得到银河、月亮、太阳直射对系统X、Y极化亮温影响的年际变化规律。本文所做的工作为后续综合孔径辐射计系统的进一步优化和设计提供仿真平台,也为接下来海表面盐度探测的硬件系统指标设计以及应用反演提供参考依据。
[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.
【学位授予单位】：中国科学院国家空间科学中心
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P715.7

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