Improving Chinese Terrestrial CO2 Flux estimates by Imposing Extra Constraints from Chinese and Asian Surface CO2 Observation
Quantifying the carbon flux in China is essential both for understanding the global and regional carbon balance. However, natural carbon sources and sinks over China’s terrestrial land ecosystems still have an uncertain magnitude.
Recently, Prof. CHEN Baozhang’s group at the Institute of Geographic Sciences and Natural Resources Research (IGSNRR) has presented an estimate of net ecosystem CO2 exchange (NEE) over China for the years 2001–2010 using the CarbonTracker Data Assimilation System for CO2 (CTDAS). Additional Chinese and Asian CO2 observations have used in CTDAS to improve the estimate of China.
The research found the combined terrestrial ecosystems in China absorbed about -0.33 Pg C yr-1 with uncertainty ranging from -0.29 to -0.64 Pg C yr-1(carbon sinks were referred with a negative sign). The peak-to-peak amplitude of inter-annual variability (IAV) of the Chinese terrestrial ecosystem carbon flux is 0.21 Pg C yr-1 (~64% of mean annual average), with the smallest CO2 sink (–0.19 Pg C yr-1) in 2003 and the largest CO2 sink (–0.40 Pg C yr-1) in 2007 corresponding with favorable temperature in spring/winter. Furthermore, we stress that the estimate of Chinese terrestrial ecosystem CO2 uptake based on inverse modeling strongly depends on a limited number of atmospheric CO2 observations used. More observations in China specifically, and in Asia in general are needed to improve the accuracy of terrestrial carbon budgeting for this region.
The study was published in Journal of Geophysical Research in March 2014, entitled “Net terrestrial CO2 exchange over China during 2001-2010 estimated with an ensemble data assimilation system for atmospheric CO2”.
