Aeolus星载测风激光雷达进展综述

Review of the progress of Aeolus space-borne wind measurement lidar

大气风场是气象中十分关键的要素之一,星载多普勒测风激光雷达能够实现大范围、高精度、不间断的风场测量,对于数值天气预报精度提升、气候研究和环境保护都有重要的意义。星载测风激光雷达的研究自20世纪至今已经有近30余年,在这个过程中,Aeolus是目前唯一成功发射的星载测风卫星。文中从Aeolus计划的提出开始,回顾了Aeolus的有效载荷ALADIN原理样机的地面试验,机载原型研发和机载试验的过程;对卫星发射至今的主要数据验证活动以及结果进行了总结,阐述了Aeolus产品出现误差的原因;针对Aeolus数据产品的实际应用,总结了星载测风数据对于气象研究的重要性和必要性;结合Aeolus的方案进行优化和模拟仿真,展示了仿真的结果。最后分析了Aeolus的数据特点,结合我国星载测风研究进程和气象领域的测风需求,提出了几点可以参考的内容和需要提高的技术,同时分析了三种不同的星载测风体制,其中混合体制的星载测风激光雷达具有优势,可作为我国未来研制星载测风卫星的主要方向。

Significance Atmospheric wind field is a crucial element in meteorology and a primary driving factor for global carbon cycling,aerosol transport,energy exchange,and weather changes.Although satellite-based atmospheric observations have a history of several decades,progress in measuring the global 3D wind field has been slow.A clear need for improving this situation is to establish a globally covered,high-resolution atmospheric wind observation system.Currently,the primary observation method for wind profiles is by using radiosondes,but it is impossible to obtain corresponding sounding data for regions where instruments are difficult to install and maintain,such as oceans or deserts.Therefore,wind measurement in these regions is usually performed by carrying sounding instruments on flights or ships,which is costly and subject to the conditions of detection.Satellite-based Doppler wind lidars can achieve wide-range,high-precision,and uninterrupted wind field measurements,which are not affected by terrain and time compared with ground-based and airborne detection.Satellite-based wind measurement is of great significance for improving numerical weather forecast accuracy,long-term climate research,pollutant transport,and environmental protection.Research on satellite-based Doppler wind lidars has been underway for nearly 30 years since the last century,and Aeolus is currently the only successfully launched satellite for satellite-based wind measurement.Progress In the 1980s,research on laser radar technology was conducted in space,followed by some research on coherent wind measurement in the 1990s.However,due to its technical difficulty,it has not been successfully applied so far.In the 1990s,the ADM-Aeolus project was proposed.Starting in 2000,EADS-Astrium,a subsidiary of the European Aerospace and Defense Group,and more than 30 European companies jointly conducted research and development on the ALADIN payload principle prototype(Fig.2).In 2001,ESA developed a direct-detection lidar simulator for the ADM-Aeolus instrument.The simulator has a resolution of 15 m and incorporates the latest design of ALADIN in real-time.Before the official launch,ESA conducted six airborne testing activities to observe atmospheric wind profiles for various atmospheric scenarios(Tab.2)and to test,verify,optimize the data quality control algorithm,evaluate the measurement error of line-of-sight wind speed,and propose a series of data inversion optimization schemes for different situations.Aeolus was successfully launched in France in August 2018.Conclusions and Prospects This paper summarizes the main data verification activities and results of the Aeolus satellite since its launch.Until April 2022,the global random error of the L2 B data product for the Rayleigh channel is about 6 m/s and for the Mie channel is about 3.3 m/s.However,in long-term experiments,the L2 A product has significant errors in the backscatter coefficient under 2 km due to cloud interference and other factors including but not limited to low laser emission energy,calibration defects,and fluctuations in thermal pixels.This paper focuses on the practical application of the Aeolus data product and quantifies the improvement of numerical weather forecast accuracy,advancement of atmospheric dynamics research,and progress on pollutant and environmental research.Based on the Aeolus design,parameter optimization and simulation were conducted,and the simulation results were presented.Finally,the data characteristics of Aeolus were analyzed,and seven factors that need improvement were proposed based on China's research progress in satellite-based wind measurement and wind measurement requirements in the meteorological field,including laser emission energy,data inversion,and equipment development.The paper also analyzed the characteristics of coherent lidar wind measurement and hybrid lidar wind measurement schemes.Among them,the hybrid lidar wind measurement scheme has advantages in the accuracy and quantity of the detection data,and can be considered as the main direction for China's future development of satellite-based wind measurement.