Simulation Of Spaceborne Wind Lidar Technology Based On Mie Scattering

Wind is one of the basic variables describing the state of the atmosphere.The accurate measurement of the global wind field is of great importance for numerical weather prediction.Lidar has a high spatial and temporal resolution,and it has developed rapidly in recent decades.It plays an increasingly important role in earth observation,especially in the detection of atmospheric wind field.The spaceborne doppler wind lidar can accurately measure the global wind field.On August 24,2018,the world's first spaceborne doppler wind lidar was launched in France,but the lidar is still in the debugging stage.It is an important task to use simulation system to study how to improve the measurement accuracy of wind before the data was released.Doppler wind lidar uses the backscattering signal of particles(molecular and aerosol)in the atmosphere to measure wind velocity.However,the backscattering intensity and backscattering spectrum of molecules and aerosols are different.In the actual measurement,it is necessary to invert the wind field with different signals based on the vertical distribution of molecules and aerosols.When the wind velocity is retrieved using the aerosol backscatter signal,it is affected by the molecular scattering signal.This paper focuses on the simulation of the Mie channel of spaceborne doppler wind lidar and the effect of molecular scattering signal on the wind velocity retrieval of the Mie channel.Firstly,the intensity and spectral distribution models of echo signals at different heights are established,and Brillouin scattering is considered when establishing the molecular scattering model.The backscattering coefficient,extinction coefficient and atmospheric transmittance profile of molecules and aerosols were calculated based on the RMA data and the 1976 U standard atmospheric model.The wind profile dataset was established based on the high-resolution sounding data of Nanjing in 2015.Then the different wind velocity retrieval algorithms of the fringe imaging technique were analyzed and compared.At the same time,for the Gaussian method,a wind velocity retrieval checklist is established.On this basis,the signal received on different bins of the Mie channel of spaceborne doppler wind lidar is caculated,and the influence of molecular scattering on wind velocity retrieval of the Mie channel of spaceborne doppler wind lidar Mie channel was studied.The results show that the molecular scattering signal will increase the retrieval error when the original signal received bythe detector is directly used for wind velocity retrieval,and the existence of the molecular scattering signal makes the retrieved wind velocity smaller than the real wind velocity.Therefore,a method to eliminate the interference of molecular scattering signals is proposed,bases on the assumption that all the photons on the channel that the number of photons is minimum come from molecular scattering.The simulation results show that the method can effectively reduce the influence of molecular scattering signal on the wind velocity retrieval of Mie channel,and it can improve the wind velocity retrieval accuracy of Mie channel.