高海况下卫星雷达高度计参数反演的影响因素分析研究

发布时间：2018-07-10 05:00

本文选题：雷达高度计 + 降雨和白沫　；参考：《华中科技大学》2016年硕士论文

【摘要】：台风飓风暴雨等极端大气和海面状况(或高海况)导致海面波浪破碎,从而在海表面上产生大量白帽和泡沫(统称白沫)。在通常海况下,雷达高度计会接收到比较有规则的海面回波波形,依据海洋模型(Brown模型)都能比较精确的反演出海面参数,能满足工程实践需求。然而,当高海况时,由于白沫和降雨对微波信号衰减和散射作用,致使高度计接收到的微波信号十分微弱,甚至失锁,这大大影响高度计海面参数的反演及其精度。本论文主要研究了高海况下白沫和降雨对高度计海洋参数反演的影响。首先分析了卫星雷达高度计海面参数测量模型和基本原理。其次,详细分析和研究了降雨对高度计参数反演影响。主要研究了降雨对微波衰减作用,Mie散射理论,辐射计测量降雨量、液态水原理,在此基础上讨论了降雨对高度计后向散射系数反演的影响,从而分析了白沫对海面风速反演的影响。随后,详细研究了白沫对高度计参数反演的影响:(1)基于大气-白沫-海水三层介质模型,运用电磁场理论计算和分析了该模型的电磁波入射反射特征,从而得到白沫对海面反射率的影响特性,以及白沫对海面后向散射系数的影响规律和误差校正值。(2)在此基础上,根据白沫覆盖率与风速的经验关系、风速与后向散射系数的关系,讨论了白沫对高度计海面风速反演的影响。(3)白沫对有效波高的反演影响分析是从高度回波波形出发,讨论了白沫对海面高度概率密度函数的影响、回波波形的影响,通过最小二乘法拟合反演出有效波高,得到白沫对有效波高反演的影响特性及其误差校正值。最后,采用海洋二号卫星测得的数据通过一定的算法分别对存在降雨和白沫时测量的后向散射系数及风速进行校正。本论文研究结果在高度计高海况参数反演与校正工作中具有较好的参考价值和应用意义。
[Abstract]:Extreme atmospheric and sea surface conditions such as typhoons, hurricanes and torrential rains (or high sea conditions) cause waves to break, resulting in a large amount of white caps and foams (collectively called foams) on the sea surface. Under normal sea conditions, radar altimeters receive regular sea surface echo waveforms. According to the ocean model (Brown model), the sea surface parameters can be accurately inverse, and can meet the engineering needs. However, when the sea is high, the microwave signal received by altimeter is very weak or even unlocked due to the attenuation and scattering of microwave signal by foam and rainfall, which greatly affects the inversion and accuracy of sea surface parameters of altimeter. In this paper, the effects of foam and rainfall on the inversion of altimeter ocean parameters are studied. Firstly, the sea surface parameter measurement model and basic principle of satellite radar altimeter are analyzed. Secondly, the influence of rainfall on altimeter parameter inversion is analyzed and studied in detail. The Mie scattering theory of rainfall on microwave attenuation, the measurement of rainfall by radiometer and the principle of liquid water are studied. Based on this, the influence of rainfall on the inversion of backscattering coefficient of altimeter is discussed. The effect of foaming on the retrieval of sea surface wind speed is analyzed. Then, the effects of foaming on the inversion of altimeter parameters are studied in detail. (1) based on the three-layer model of atmosphere, foaming and seawater, the electromagnetic wave reflection characteristics of the model are calculated and analyzed by using electromagnetic field theory. The influence characteristics of foaming on sea surface reflectivity, the influence law and error correction value of foam backscattering coefficient on sea surface are obtained. (2) based on the empirical relationship between foam coverage and wind speed, The relationship between wind speed and backscattering coefficient is discussed. The influence of foaming on the inversion of sea surface wind speed of altimeter is discussed. (3) the effect of foaming on the inversion of effective wave height is analyzed from the angle of height echo waveform, and the influence of foaming on the probability density function of sea surface height is discussed. The effect of echo waveform on the inversion of effective wave height is simulated by least square method, and the effect of foaming on the inversion of effective wave height and its error correction value are obtained. Finally, the backscattering coefficient and wind speed measured in the presence of precipitation and foaming are corrected by using the data obtained from the Ocean 2 satellite. The results of this paper have good reference value and application significance in the inversion and correction of altimeter sea condition parameters.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P714

【参考文献】