Analysis Of Carbon Flux In China Based On Inversion Of Short-wave Infrared Radiation Data From GOSAT

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change?IPCC?noted that carbon dioxide?CO₂?is one of the major greenhouse gases causing global warming.The global warming has a serious impact on the global ecosystem,political,and economic.The monthly average global CO₂ concentration monitored by the GOSAT has reached 405 ppmv in December 2017,an increase of approximately40%compared with 1870.Since the reform and opening up,China has become a high value area for CO₂ emissions due to the rapid economic development.Therefore,it has great significance to study the temporal and spatial distribution of CO₂ concentration and the distribution of carbon sources and sinks in China.In this paper,CO₂concentration and carbon flux of terrestrial ecosystems in China were analyzed by usingCO₂ concentration and carbon flux data from GOSAT and ground monitoring,respectively,as well as the auxiliary data sucuch as population density and vegetation distribution in different provinces provided by the“2014 China Statistical Yearbook”and Arcgis geographic statistical analysis method.The results showed that:?1?GOSAT data and ground observation data had good consistency,and CO₂concentration of them had obvious seasonal variation.?2?From 2011 to 2015,CO₂ concentration had obvious seasonal variation characteristics in China From 2011 to 2015.It was low in summer,and was high in spring,and the annual increase was about 2 ppm.Nevertheless,the annual growth rate of CO2 concentration in summer was higher than that in spring,it was 0.5425%in summer and was 0.46%in spring,which was contrary to the seasonal variation of CO₂concentration.In the spatial distribution,CO₂ concentration was low in the northwest and was high in the southeast.It was greater in the east and south China than that in other regions.The growth rate of CO₂ was 2.8 ppm in the northwest and was 3.42 ppm in the southeast.?3?The carbon fluxes of terrestrial ecosystems in China in 2014 had obvious seasonal variations.It was carbon sinks from April to September.It was carbon sinks in summer,which was about-1.38gCm^-2day^-1 in July.It was carbon source in other months.It was carbon source in winter,which was about 0.64 gCm^-2day^-1in November.The change of carbon flux was more drastically in summer.In summer,the high value areas of carbon sinks were mainly concentrated in the eastern region,while the high value areas of carbon sources were mainly concentrated in the western region.In winter,weak carbon sinks were mainly concentrated in the northwestern region,while most of the eastern regions showed carbon sources,which were contrary to the distribution of carbon sources and sinks in summer.Monthly carbon fluxes changes in coastal areas were more violently than that in inland areas.?4?In terrestrial ecosystems,the carbon storage capacity was strongest in the forest ecosystem,the follow was grassland ecosystem,and it was weakest in the desert ecosystem.With the increase of latitude,the annual carbon flux in forest ecosystems gradually changes from carbon sinks to carbon sources.The carbon sink value was largest in subtropical evergreen broad-leaved forests.The carbon sink value was larger in summer if the forest coverage rate was larger when in the same forest vegetation area.In autumn and winter,the carbon sink value was smaller if the forest coverage rate was larger in subtropical evergreen broad-leaved forests,which is contrary to the situation in warm-temperate deciduous broad-leaved forests and cold temperate coniferous and broad-leaved mixed forest.