Simulation Of CO2Source, Sink And Concentration Temporal And Spatial Distributions Over East Asia

In this study, the observations of atmospheric CO2concentrations at9background stations in East Asia were collected, the variations of CO2and the differences between stations were discussed on the impacts of the underlying surface, source and sink, and the seasonal variations and diurnal variations of CO2concentrations were also studied. Then the greenhouse gas CO2has been imported into the RAMS-CMAQ model, and the model has been improved by the accessions of processes of emission, diffusion, and transport. The vegetation photosynthesis and respiration model has been designed and coupled into model to represent carbon dioxide exchange between atmosphere and surface, and the RAMS-CMAQ model can simulate CO2accurately. Therefore the improved model can analogue both the processes of transport and diffusion and the processes of photosynthesis and respiration of vegetation. The surface CO2flux and spatial and temporal distribution of CO2concentration over East Asia in2007have been simulated by the improved model. The results have been evaluated with satellite data and ground-based observations, and the characteristics of spatial and temporal distributions of atmospheric carbon dioxide in China were analyzed. The results indicate as follows.(1) The results of atmospheric CO2concentrations at9background stations in East Asia revealed that the temporal and spatial variations in atmospheric CO2are analyzed. Analysis results revealed that the CO2concentrations at the observation stations exhibit strong seasonal variations and diurnal variations. There are inverse relationships between the mean CO2concentration and the vegetable amount of underlying surface, and between the range of the concentration daily variation and the vegetable amount, respectively. The annually averaged CO2concentration rose constantly from2004to2008at Mt. Waliguan, one of global background stations, with an increase rate of2.28ppmv/a.(2) The CO2exchange between surface and atmosphere model—VPRM model were designed, and the spatial and temporal distributions of GPP (Gross Primary Production) simulated by the VPRM model conformed to the seasonal variation characteristics of short wave radiation, temperature, precipitation and distributions of vegetation in East Asia. The results generally reproduced the seasonal variation of GPP at observation stations, and presented linear correlativity with the observations, and correlation coefficients were above0.9.(3) The greenhouse gas CO2and the CO2model had been imported into the RAMS-CMAQ model, and the model has been improved by the accessions of processes of emission, diffusion, transport and exchange between surface and atmosphere. The temporal and spatial distributions of CO2concentration over East Asia in2007were simulated and compared with observations, the results generally reproduced the seasonal variation of atmospheric carbon dioxide in East Asia, especially in the stations which are slightly affected by anthropogenic random emission, the correlation coefficients of observed and modeled CO2concentration are more than0.8. In general, the source data, the CO2flux simulated by CO2model, and the transport and diffusion of atmospheric carbon dioxide simulated by CMAQ in the model system are accurate.(4) The temporal and spatial distributions of CO2concentration over East Asia in2007were analyzed, and result revealed the spatio-temporal variations of carbon dioxide concentration are severe in lower atmosphere, and light in higher layer. There are positive relationships between surface CO2concentrations and anthropogenic source amount, and influences of anthropogenic source, respectively. There are inverse relationships between surface CO2concentrations and atmospheric vertical diffusibility.(5) The results of comparisons show that CO2concentrations in the first model level had higher frequency variations relative to the modeled averaged column concentration. So the column CO2inversed from satellite cannot reproduce precisely the variations of atmospheric CO2concentration in boundary layer.