| For decades,human activities have caused a dramatic increase in the concentration of greenhouse gases and pollutants in the atmosphere.The large increase in greenhouse gases,especially carbon dioxide,has had a major impact on the global climate.At present,people have reached consensus on the view that the greenhouse effect of carbon dioxide is an important factor that causes global change.Therefore,it is of great significance to strengthen the scientific observation and understanding of the global carbon cycle.However,the lack of accurate and reliable data on carbon flux measurement in terrestrial ecosystems has greatly hampered human understanding of the carbon cycle mechanism and makes it difficult for countries to reach consensus on carbon reduction issues.Therefore,only the accurate and complete measurement of man-made and natural source sinks of carbon dioxide gas and long-term and effective observation data can support subsequent analysis and induction research in order to obtain the most accurate understanding of the global carbon cycle.With regard to the existing technical means,the detection accuracy of the ground or airborne measurement stations is high but the distribution is sparse,and the carbon flux estimation results for the interior of the continent based on the atmospheric transmission model have a high degree of uncertainty.Passive satellite remote sensing(SCIAMACHY,TES,AIRS,IASI,GOSAT,OCO-2,and TANSAT)can obtain dense CO2 observation data,which has improved human understanding of global CO2 distribution to a certain degree,but also exposed some obvious defects.The differential absorption lidar technology detects atmospheric composition gas,can effectively compensate for the observational defects of passive satellites in the detection mechanism,and can provide a more accurate estimation of carbon flux,making a more important contribution to carbon cycle research.However,at present,the development of the main satellite remote sensing is still at a preliminary stage in the world.The development of the prototype of the airborne multi-wavelength differential absorption laser radar system developed by the US NASA advanced technology has achieved relatively successful experiments,but the development of the spaceborne laser radar system is difficult and difficult.The inversion process produces errors due to changes in the distribution of atmospheric temperature pressure.Based on this,this paper mainly did the following work:(1)A validation and comparison method for the observation of atmospheric CO2 concentration data by passive satellites is proposed.Due to the limitation of the detection mechanism of satellites GOSAT and OCO-2 in orbit,the accuracy of data retrieval of XC02 data needs to be considered.Based on the differences in the distribution characteristics of XC02 concentration in different latitudes and different surface conditions,a complete verification and comparison work was conducted using the TCCON observation network data of the foundation,and the passive satellites were observed under different observation patterns,latitudes,and different surface coverages.Accuracy and accuracy of data atmospheric carbon dioxide concentration,accurate assessment data were obtained.At the same time,multi-source remote sensing data(re-analysis of meteorological data,MODIS ground parameters,etc.)are used to analyze the sensitivity of satellite detection of carbon dioxide and accuracy for various parameters of the atmosphere and the ground,and to provide effective data for providing data correction methods.(2)A method for inversion of atmospheric carbon dioxide concentration by a spaceborne multi-wavelength differential absorption lidar is proposed.Based on the technology of dual-wavelength differential absorption lidar to detect atmospheric carbon dioxide,an improved multi-wavelength differential absorption lidar inversion method is proposed.This inversion method can inversion obtain high-precision carbon dioxide column concentration and layered profile concentration on the signal-to-noise ratio and the number of wavelengths that satisfy certain conditions.By modifying the signal-to-noise ratio and the number of experimental wavelengths and comparing the results of simulation experiments,the performance of the improved multi-wavelength differential absorption lidar inversion method was evaluated.The simulated data inversion accuracy is within 0.07 ppm.Compared with other multi-wavelength inversion algorithms,there are more accurate and accurate experimental results.(3)Combining a variety of environmental remote sensing parameters,this paper proposes a causal analysis of the spatial distribution and variation of satellite atmospheric carbon dioxide concentration data.First,the observational data of GOSAT and OCO-2 satellites during the observation period were compared.Analyze the differences in the distribution of atmospheric carbon dioxide concentration detected by the two satellites globally,including spatial coverage and deviations from different surface observations.Then,using the long-term satellite observation data,the global carbon dioxide concentration distribution and changes were analyzed.Finally,combined with the satellite chlorophyll fluorescence data retrieved by satellites,and other multi-source remote sensing data(such as land cover,total vegetation productivity,etc.),the characteristics of temporal and spatial distribution of carbon dioxide and seasonal changes were analyzed at the global scale and in China,and the carbon dioxide concentration and vegetation were analyzed.Fluorescence changes and other correlations between the parameters that reflect the vegetation.(4)Finally,summarizing all the work of this paper,and based on the research content,put forward new requirements and prospects for the next phase of the study of active and passive satellites combined with CO2 observation. |
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