Improving Chinese Terrestrial CO₂ Flux estimates by Imposing Extra Constraints from Chinese and Asian Surface CO₂ Observation

Jun 16, 2014     Email"> PrintText Size

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”.