Multi-Channel Improvement Of The Sodium Temperature/Wind Lidar For Initial Results Of Heat Flux And Sodium Flux

With the improvement of the comprehensive national power and the scientific level of our country,lidar has become an indispensable means of atmospheric detection.With the development of scientific theories,we are increasingly in need of observations from technologically advanced multi-channel LiDAR to support theoretical studies.The multi-channel LiDAR is able to achieve all the science missions of the dual?channel LiDAR and can further provide unprecedented observations for the theoretical research of the middle and upper atmosphere.The content of this paper includes two parts:the principle of atmospheric detection of multi-channel sodium LiDAR and the improvement plan and results of the multi-channel LiDAR.Firstly,I introduced the vertical structure of the atmosphere,the interaction mechanism between the atmosphere and the laser,the detection principle of the LiDAR,and especially the theoretical basis of the sodium LiDAR.Then,a multi-channel improvement plan is proposed with the consideration of the actual situation and needs.The LiDAR channel expansion performance is also improved to simplify the follow-up LiDAR channel expansion work.A new main focus reception telescope structure and a cage fiber coupling mechanical structure are adopted to effectively improve the optical reception efficiency.The main pulse circuit is redesigned to improve the performance of the photoelectric conversion circuit.As a consequence,the rising edge of the output pulse is optimized from?150us to?60ns.We also redesigned the subsequent optical path and improved the light-shielding performance of the optical path.In addition,the feedforward proportional integral differential control method effectively improves the stability of the echo signal chopper.The results of the improved multi-channel LiDAR show that the data consistency of the multiple channels is very good.Using the newly developed multi-channel LiDAR data,I studied the heat and sodium fluxes in Hefei(31.9°N,117.17°E)from July 2017 to March 2018.The vertical heat flux is generally downward and the heat flux reaches a maximum of?-1.7 K m/s at the height of approximately 100 km.The transport direction of the vertical sodium flux is generally downward,reaching a maximum of-90 m/s/cm~2 at?93 km.