分子散射对星载测风激光雷达Mie通道的影响

多普勒测风激光雷达利用大气中粒子的后向散射信号谱测量风速,但分子和气溶胶后向散射强度和光谱宽度差异较大,所以在实际测量中需要根据分子和气溶胶的垂直分布情况选择不同的信号。当选择气溶胶散射信号反演风速时,会受到分子散射信号的影响。本文研究了分子散射对星载多普勒测风激光雷达Mie通道风速反演的影响问题,并进行了仿真模拟,结果表明,当直接利用探测器接收到的原始信号进行风速反演时,分子散射信号会增大反演误差;因此基于探测器所有通道上光子数最小的一个通道上的光子全部来自于分子散射的假设,提出了一种减小分子散射信号对Mie通道风速反演干扰的方法,通过模拟表明,利用该方法后,对流层内风速反演精度明显提高,相对误差从原来的20%～30%减小到10%以内,除近地层以外的相对误差小于5%;但平流层内的误差几乎不发生变化。

Influence of molecular scattering on Mie channel of spaceborne wind lidar

Doppler wind lidar uses the spectrum of backscattering signal of particles in atmosphere to measure the wind velocity,but the intensities of molecular and aerosol backscattering are quite different. Therefore,in practice,different signals need to be selected according to the vertical distribution of molecules and aerosols. Molecular scattering signal will have interference when the aerosol scattering signal is selected to calculate the wind velocity. In this paper,the influence of molecular scattering to calculated wind velocity of Mie channel of spaceborne Doppler wind lidar is analyzed. The simulation results show that when the original signal received by the detector is directly used for calculatingwind velocity,molecular scattering signal will increase the error of calculated wind velocity. Therefore,a method to eliminate the interference of molecular scattering signals is proposed,bases on the assumptionthat all the photons on the channel that the number of photons is minimum,come from molecular scattering. The simulation shows that the accuracy of calculated wind velocity in the troposphere increases obviously. The relative error dropped from 20%~30% to 10%. Then,the method is further developed,the relative error in the troposphere is less than 5% except for the near-surface layer. However,the error in the stratosphere hardly changes.