Nested atmospheric inversion for the terrestrial carbon sources and sinks in China

Abstract

In this study, we establish a nested atmospheric inversion system with a focus on China using the Bayesian method. The global surface is separated into 43 regions based on the 22 TransCom large regions, with 13 small regions in China. Monthly CO₂ concentrations from 130 GlobalView sites and 3 additional China sites are used in this system. The core component of this system is an atmospheric transport matrix, which is created using the TM5 model with a horizontal resolution of 3° × 2°. The net carbon fluxes over the 43 global land and ocean regions are inverted for the period from 2002 to 2008. The inverted global terrestrial carbon sinks mainly occur in boreal Asia, South and Southeast Asia, eastern America and southern South America. Most China areas appear to be carbon sinks, with strongest carbon sinks located in Northeast China. From 2002 to 2008, the global terrestrial carbon sink has an increasing trend, with the lowest carbon sink in 2002. The inter-annual variation (IAV) of the land sinks shows remarkable correlation with the El Niño Southern Oscillation (ENSO). The terrestrial carbon sinks in China also show an increasing trend. However, the IAV in China is not the same as that of the globe. There is relatively stronger land sink in 2002, lowest sink in 2006, and strongest sink in 2007 in China. This IAV could be reasonably explained with the IAVs of temperature and precipitation in China. The mean global and China terrestrial carbon sinks over the period 2002–2008 are −3.20 ± 0.63 and −0.28 ± 0.18 PgC yr⁻¹, respectively. Considering the carbon emissions in the form of reactive biogenic volatile organic compounds (BVOCs) and from the import of wood and food, we further estimate that China's land sink is about −0.31 PgC yr⁻¹

Primary estimation of Chinese terrestrial carbon sequestration during 2001–2010

“…And our estimate was significantly higher than that during 1981-2000 based on a variety of ways [25], and was also higher than the sink during 2001-2010 (0.28-0.33 PgC a -1 , Table 8) obtained from atmospheric inversion method [24,83], models [79] and resource inventory method [84,85]. These differences resulted primarily for two reasons.…”

Carbon balance of China constrained by CONTRAIL aircraft CO<sub>2</sub> measurements

“…China has a vast land area of 960 × 10 6 ha, and nearly 80 % of the land areas are covered with various types of vegetation including forest (16.5 %), grass (34.8 %), shrubs (18.5 %), croplands (11.2 %), and other types (Fang et al, 2007). Using the methods of bottom-up (inventory survey and process-based ecosystem model) and top-down (atmospheric inversion) approaches, many studies have been conducted during the past decade to estimate China's terrestrial ecosystem carbon sinks (e.g., Cao et al, 2003;Fang et al, 2007;Piao et al, 2009;Tian et al, 2011;Jiang et al, 2013). Fang et al (2007) estimated the land sinks in China could offset 20.0-26.8 % of its industrial carbon emissions.…”

“…One of the main reasons may be attributed to the lack of enough CO 2 concentration observations. Jiang et al (2013) pointed out that due to lack of sufficient observations, most regions of the country have a low regional and annual uncertainty reduction percentage (< 10 %) by way of atmospheric inversion, especially for South and Southwest China, and the overall uncertainty reduction is relatively lower compared with North America and Europe.…”

A regional carbon data assimilation system and its preliminary evaluation in East Asia

“…biospheric and oceanic) CO 2 emissions at the ecological scale (e.g. Deng et al, 2007;Feng et al, 2009;Peters et al, 2005Peters et al, , 2007Jiang et al, 2013;Peylin et al, 2013).…”