Definitions and methods to estimate regional land carbon fluxes for the second phase of the REgional Carbon Cycle Assessment and Processes Project (RECCAP-2)
Definitions and methods to estimate regional land carbon fluxes for the second phase of the REgional Carbon Cycle Assessment and Processes Project (RECCAP-2)
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DOI：
10.5194/gmd-15-1289-2022
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发表时间：
2022-02-16
影响因子：
5.1
通讯作者：
Zheng, Bo
中科院分区：
文献类型：
--
作者：
Ciais, Philippe;Bastos, Ana;Zheng, Bo
区域陆地碳预算提供了对陆地吸收大气二氧化碳的空间分布的深入了解，可用于评估碳循环模型，并确定陆地额外减缓努力的基线。科学界一直在参与提供基于观测的区域碳预算估计数，办法是将大气CO2观测缩小为具有大气逆温的地表通量，使用陆地生态系统碳储存变化清单，扩大当地实地观测，如具有网格气候和遥感场的通量塔，或整合数据驱动或面向过程的陆地碳循环模型。在RECCAP-1项目中，收集覆盖整个地球仪的九个区域的区域碳预算的第一次协调尝试提供了2000-2009年十年的估计数，但由于不同的定义和报告或省略的组分通量，这些预算在区域之间不具有可比性。最近人们认识到，人类活动和河流造成的碳横向流动将一个地区的二氧化碳吸收与另一个地区的二氧化碳释放联系起来，这也需要更好的定义和议定书，以达成协调一致的区域预算，这种预算可以汇总到地球仪的规模，并与大气二氧化碳增长率和反演结果进行比较。在这项研究中，使用由全球碳项目协调的国际倡议RECCAP-2，其目的是根据覆盖地球仪的10个地区的观测结果更新过去20年的区域碳预算，比前体项目更好地协调，我们提供了使用大气反演结果来匹配自下而上的碳核算和模型的建议，我们定义了负责每个区域的每个研究小组应该报告的净陆地大气碳交换的不同组分通量。特别注意的是横向通量，内陆水通量和土地利用通量。
Regional land carbon budgets provide insights into the spatial distribution of the land uptake of atmospheric carbon dioxide and can be used to evaluate carbon cycle models and to define baselines for land-based additional mitigation efforts. The scientific community has been involved in providing observation-based estimates of regional carbon budgets either by downscaling atmospheric CO2 observations into surface fluxes with atmospheric inversions, by using inventories of carbon stock changes in terrestrial ecosystems, by upscaling local field observations such as flux towers with gridded climate and remote sensing fields, or by integrating data-driven or process-oriented terrestrial carbon cycle models. The first coordinated attempt to collect regional carbon budgets for nine regions covering the entire globe in the RECCAP-1 project has delivered estimates for the decade 2000-2009, but these budgets were not comparable between regions due to different definitions and component fluxes being reported or omitted. The recent recognition of lateral fluxes of carbon by human activities and rivers that connect CO2 uptake in one area with its release in another also requires better definitions and protocols to reach harmonized regional budgets that can be summed up to a globe scale and compared with the atmospheric CO2 growth rate and inversion results. In this study, using the international initiative RECCAP-2 coordinated by the Global Carbon Project, which aims to be an update to regional carbon budgets over the last 2 decades based on observations for 10 regions covering the globe with a better harmonization than the precursor project, we provide recommendations for using atmospheric inversion results to match bottom-up carbon accounting and models, and we define the different component fluxes of the net land atmosphere carbon exchange that should be reported by each research group in charge of each region. Special attention is given to lateral fluxes, inland water fluxes, and land use fluxes.