A Study Of Atmospheric CO₂ Spatial-temporal Distribution And Its Influencing Factors In China Based On Satellite Observation

Global warming and extreme weather events have gradually been confirmed by lots of scientific studies.Carbon dioxide became one of the most crucial anthropogenic greenhouse gas because of absorbing the long wavelength radiation of the earth.The relationships between CO₂ increase and climate change have been paid wide attentions.Therefore,the study of surface measurements,spatial-temporal characteristics,and influence mechanism of CO₂ has become an important research field of atmospheric science.Remote sensing of CO₂ from space is capable of acquiring global observation data.This paper has focused on atmospheric CO₂ concentration of China' s land area.Satellite-based CO₂ concentrations from near-surface and mid-troposphere were used.To evaluate CO₂ from satellite observation,we compared CO₂ from satellite with data from ground-based stations.Then,we analyzed the spatial-temporal characteristics of GOSAT and AIRS satellite data from 2010 to 2012.We compared the differences between near-surface and mid-troposphere CO₂.According to the time sequence characteristics of surface CO₂,we explored the distribution difference in China by using clustering analysis.Combined with the carbon source-sink,meteorogical conditions and social economic factors,the driving factors of spatial-temporal variation were analyzed.The result of this study may provide more information about the influencing mechanism of CO₂ and deepen the recognition for carbon cycle.Major results of this study were as follows:?1?Satellite-based CO₂ has showed consistent time fluctuations with ground observation.The amplitude of ground observation was higher than that of satellite observation.Regional background station verification had higher correlation coefficient.The correlation coefficients between GOSAT-CO₂,AIRS-CO₂ and station CO₂ in Waliguan station were 0.85 and 0.59,respectively.GOSAT-CO₂ has better sensitivity to concentration changes from surface CO₂ emission and absorption compare with AIRS-CO₂.?2?The spatial distribution of near-surface and mid-troposphere CO₂ concentrations were unveiled in China.The average concentration of near-surface CO₂ from 2010 to 2012 was higher in the southeast China than northwest.The highest concentration of near-surface CO₂ concentration was 392.37 ppm.There were two centers of high CO₂ concentrations in central-China and south Yunnan Province.The latitude zonal distribution showed higher value in the south,maximum peak value appeared on the 29°N parallel circle.On the other hand,mid-troposphere CO₂ concentrations were higher in the north as contrary to near-surface concentrations.The highest and lowest concentrations in the mid-troposphere were 393.7 ppm and 389 ppm,respectively.The latitude zonal distribution showed higher value in the north,maximum peak value appeared on the 44° N parallel circle.The study area was devided into 7 subregions with similar near-suface concentration fluctuation characteristic by using clustering analysis.As comparison between Koppen-Geiger climate zones and identified subregion clusters revealed very good spatial overlapping.?3?The temporal variation of near-surface and mid-troposphere CO₂ concentrations were unveiled in China.The annual growth rate was about 1.8?2.2 ppm/a.There was a significant seasonal CO₂ variation with peak concentration in spring and the lowest concentration in summer for near-surface CO₂.The spring-summer CO₂ concentration was higher than that of autumn-winter season for mid-troposphere CO₂.There were significant time lag effect of AIRS-CO₂ because of the vertical atmospheric gas mixing.Temporal variation of typical cities and subregions showed different results due to various environmental factors such as geographical position.?4?Atmospheric CO₂ concentrations had significant positive correlation with carbon emissions on a regional scale?R2=0.87,p<0.01?.The temporal variation of near-surface CO₂ could be explained by vegetation and temperature,showing negative correlations in most of China.Grading statistic of altitude and CO₂ concentration results showed two high-value region in less than 1 km and 1.5-2 km,same with the elevation distribution trend of the population and GDP.Dilution rate was not a statistically significant influence factor of CO₂ temporal variation.?5?The quantitative analysis on the relationship between atmospheric CO₂ concentrations and various influence factors were investigated based on GWR?Geographically Weighted Regression?analysis.As a result,carbon emissions,vegetation,altitude,temperature,population density,GDP,and dilution rate were contained in GWR model as independent variables.Simulation results of GRW?R2=0.83,p<0.01?were increased comparing to OLS?Ordinary Least Squares?results?R2=0.73,p<0.01?.Consequently,the most universal factors were carbon emissions and vegetation.The influence of temperature,altitude,and social economic factors was also widespread.Effects of dilution rate on CO₂ concentration appeared only in autumn.Artificial carbon emissions effect on CO₂ concentration showed promoting relationship in east China.