星载激光测高仪海面回波的仿真与分析

The Simulation and Analyses of Received Waveform from Ocean Surface Based on Satellite Laser Altimeter

星载激光测高仪发射的1 064 nm波长激光被波动海洋表面反射,系统接收的时间波形与瞬时海面波浪分布相关。而海面波浪又直接受海面风速影响,因此可以通过观测激光测高仪回波变化监测不同风速下海态变化。本文依据激光雷达方程,利用蒙特卡洛法模拟不同风速下的海面波浪分布,通过光线追击建立海面回波波形仿真器;以地球科学激光测高系统（geo-science laser altimeter system,GLAS）参数为输入,仿真得到不同风速下的海面回波：发现当海面风速在3~10 m/s之间时,回波呈单峰高斯波形,与GLAS发布的实际回波相符;且回波脉宽,以及有效能量反射率（即有效回波能量与发射能量之比）与实测参数误差小于10%。进一步分析可知,回波特征参数与海面风速之间存在显著关联,为利用激光测高仪大规模精确反演海洋表面风速奠定了基础。

The transmitted pulse at 1 064 nm wavelength by Satellite Laser Altimeter can be reflected by fluctuant ocean surface. There is close relation between received waveform characteristic and instantaneous distribution of sea wave. At same time,the wind speed above sea surface makes an effect on sea state. Because of this reason,through observing the different received waveforms can monitor various sea states under different wind speeds. This paper makes use of Monte Carlo to show the distribution of sea wave,and builds received waveform model according to laser radar equation; Taking the parameters of Geoscience Laser Altimeter System（ GLAS） as input,calculating and simulating the received waveform at different wind speed,the results show that when wind speed is from 3 m/s to 10 m/s,the return waveform is approximately single Gaussian,whose shapes is similar to real waveforms,and the errors of root mean square（ RMS） width and the radio of the energy between received and transmitted is not more than10%,which have great coherence with real waveforms. For further analyses,waveform characteristic are close link to sea wind speed,these results make contributions to inverse wind speed in great scale and precisely from waveform characteristic next stage.