Simulation And Experimental Research Of Airborne CO₂ Measurement Lidar

The increasing concentration of greenhouse gases,for example CO₂,is considered to be one of the main factors affecting the climate and its change of the earth.Accurate measurements of atmospheric greenhouse gases?GHG?make people a better understand global climate change,in particular the exchange of greenhouse gases among atmosphere,biosphere and the oceans,and verify the accuracy of greenhouse gases detection satellites.This will effectively limit greenhouse gases emissions.Firstly,this paper briefly introduces the research background of active and passive remote sensing to detect carbon dioxide and the related developments at home and abroad.The working principle and inversion method of integral path differential absorption lidar are also introduced.The effects of surface reflectance and aerosol optical depth on the echo power,signal-to-noise ratio and relative random error of spaceborne/airborne lidar are discussed in detail.The results show that under the given parameters of spaceborne lidar system,the single pulse echo power range is 0.299 nW to 321 nW;The signal-to-noise ratio of the single pulse echo detector is more than 23,and after accumulating 148?land?/296?ocean?pulses,the signal-to-noise ratio of the detector is above 26dB.The sea area near the Sahara desert and the Arabian Peninsula contributes the largest relative random error due to the low surface reflectance and higher aerosol optical depth,and the maximum relative random error occurs in spring of the Northern Hemisphere from the seasonal point of view.It reaches 0.22%?0.88ppm?,which meets the requirement of 1ppm maximum random error detection.We establish an airborne scaling model for spaceborne lidar to demonstrate the spaceborne system.Under the given parameters of airborne lidar system,the single pulse echo power ranges from 2.1nW to 502.5 nW.The signal-to-noise ratio of single pulse echo detector is more than 41 while the detector signal-to-noise ratio of 148times?land?/296times?ocean?pulse is more than 27dB.From the seasonal point of view,the maximum relative random error in spring is the largest,reaching 0.15%?0.6 ppm?,which can be used to verify spaceborne system.The measurement performance of the Lidar system parameters in the global range is preliminarily evaluated,and the reference data for the related research are given.From the end of 2018 to the beginning of 2019,airborne experiments were carried out in Xi'an and Shanhaiguan,and a part of the leveling stage of a 7km flight test at Shanhaiguan was analyzed.The preliminary inversion results show that the value of differential absorption optical thickness?DAOD?is 0.4337,and the concentration of CO₂ column is 419±2 ppm,the standard deviation is 3.7687 ppm.