| Spaceborne Doppler wind lidar is one of the most effective equipments to obtain global wind field information,which has become a hot field for scientists in space research.Domestic scientific institutions have proposed the spaceborne wind measurement project,which combines the direct detection and the coherent detection.It aims to realize 3D wind field observations during the height range of 0km～30km.In this paper,the direct receiver of the combined system is developed based on the requirements of spaceborne wind measurement.And a technique to retrieve horizontal wind vectors in real time based on the coherent detection data is proposed for the project.A spaceborne wind lidar optical receiver is developed in this paper.The altitude of the satellite orbit is 400km.The F-P interferometer is designed specially to eliminate the influence on Doppler frequency analysis caused by satellite operation.The performance of the receiver is simulated based on the special design and the results show that the wind speed error is 2.8m/s with maximum wind speed at the height of 30km.The structure of the receiver is stable,reliable,and highly integrated with the size of 50mm×300mm×80mm,adapting to the spaceborne requirements of stability and small scale.The main optical elements of the receiver are connected by molecular force and reversely inserted into the fillister of the receiver shell.The prototype of the direct detection receiver is set up based on the theoretical analysis,and the performance of the receiver is tested and analyzed then.Real-time wind vectors obtained by Doppler lidar are usually calculated by the geometric method under additional assumptions.To obtain global wind vectors,the assimilation interpolation technology of microwave radar is optimized and applied to the lidar data for real-time inversion of horizontal wind vectors.The wind vector on the analysis point is calculated point-by-point.The wind speed influence of other observation points on the analysis point is measured by the error covariance function based on the distance between the two points,which improves the calculation accuracy compared with the geometric method.Different wind fields are simulated to verify the accuracy of the assimilation interpolation technology.The results show that the assimilation interpolation technology is reliable and can display the detailed characteristics of the wind field in real time.Further,the observation data of Lanzhou Airport from August 2019 to March 2020 are processed by assimilation interpolation technology.Several wind shear cases are obtained accurately based on the horizontal wind vectors,and the wind shear information is in good agreement with the airport reports,which further verifies the reliability of the assimilation interpolation technology in real-time inversion of lidar horizontal wind vectors. |
