SEASONAL CHANGING TREND OF CO_2 CONCENTRATION RESPONSING TO CARBON ABSORPTION OF VEGETAION OBSERVED BY SATELLITES

摘要

It is not exactly known how the seasonal variations of CO_2 concentration such as its seasonal peak and amplitude etc., are influenced by vegetation carbon absorption. This paper presents the seasonal changing trend of CO_2 concentration affected by the seasonal activity of vegetation carbon absorption observed by Greenhouse Gases Observing Satellite (GOSAT). We extracted the seasonal changing characteristic values of CO_2 concentration using the global mapping of column-averaged CO_2 dry-air mole fraction (XCO_2) retrievals from GOSAT observing data during June 2009 to May 2014. The seasonal changing characteristic values of CO_2 concentration mainly include the amplitudes, the peak and its time of XCO_2 seasonal variations. As a result, it is found that the amplitude of XCO_2 seasonal variation is spatially corresponding to that of the normalized difference vegetation index (NDVI) from Moderate Resolution Imaging Spectroradiometer (MODIS) which could indicate the magnitude of vegetation carbon absorption. Additionally the seasonal variation of XCO_2 is strongly correlated with the seasonal variation of NDVI over vegetation covers in the northern hemisphere.