Global atmospheric CO2 inverse models converging on neutral tropical land exchange, but disagreeing on fossil fuel and atmospheric growth rate
Global atmospheric CO2 inverse models converging on neutral tropical land exchange, but disagreeing on fossil fuel and atmospheric growth rate
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DOI：
10.5194/bg-16-117-2019
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发表时间：
2019-01-16
期刊：
影响因子：
4.9
通讯作者：
Yin, Yi
中科院分区：
文献类型：
--
作者：
Gaubert, Benjamin;Stephens, Britton B.;Yin, Yi
我们已经比较了一套最近的全球CO2大气反演结果，独立的空中观测和彼此之间，以评估其依赖于北方外热带（NET）垂直运输的差异，并确定一些驱动程序的模型传播。我们评估后的CO2浓度分布对从高性能仪器化机载平台环境研究（HIAPER）极点到极点观测（HIPPO）飞机运动在2009-2011年太平洋中部的观测。虽然模型在反演方法，同化观测，以前的通量和运输模式不同，他们广泛的纬度分离的土地通量收敛显着自大气碳循环反演相互比较（TransCom 3）和区域碳循环评估和过程（RECCAP）项目，与模型传播减少了80%，因为TransCom 3和70%，因为RECCAP。大多数模拟的CO2场与HIPPO观测相当吻合，特别是对于北方半球的年平均垂直梯度。北方垂直混合不再是北方与热带（T）年通量差异的主要驱动因素。我们较新的一套模型仍然给出了北方外热带土地的吸收，相对于以前的估计是适度的（Gurney等人，2002; Peylin等人，2013年）和2009-2011年近中性热带土地吸收。考虑到毁林所致排放量的估计数，这意味着相对于历史估计数而言，完整热带森林的持续吸收量很大（Gurney等人，2002; Peylin等人，2013年）。这些模型在其他时间段（2004-2014年，2001-2004年，1992-1996年）的结果以及对TransCom 3 Level 2和RECCAP结果的重新评估证实，几十年来，包括森林砍伐在内的热带陆地碳通量一直接近中性。然而，模式仍然有很大的分歧，海洋-陆地分割。化石燃料（FF）和大气增长率的条款已被认为是最知名的条款在全球碳预算，但我们表明，他们目前限制了我们的能力，以评估区域尺度的陆地通量和海洋陆地分区的模式合奏。
We have compared a suite of recent global CO2 atmospheric inversion results to independent airborne observations and to each other, to assess their dependence on differences in northern extratropical (NET) vertical transport and to identify some of the drivers of model spread. We evaluate posterior CO2 concentration profiles against observations from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) aircraft campaigns over the mid-Pacific in 2009-2011. Although the models differ in inverse approaches, assimilated observations, prior fluxes, and transport models, their broad latitudinal separation of land fluxes has converged significantly since the Atmospheric Carbon Cycle Inversion Intercomparison (TransCom 3) and the REgional Carbon Cycle Assessment and Processes (RECCAP) projects, with model spread reduced by 80% since TransCom 3 and 70% since RECCAP. Most modeled CO2 fields agree reasonably well with the HIPPO observations, specifically for the annual mean vertical gradients in the Northern Hemisphere. Northern Hemisphere vertical mixing no longer appears to be a dominant driver of northern versus tropical (T) annual flux differences. Our newer suite of models still gives northern extratropical land uptake that is modest relative to previous estimates (Gurney et al., 2002; Peylin et al., 2013) and near-neutral tropical land uptake for 2009-2011. Given estimates of emissions from deforestation, this implies a continued uptake in intact tropical forests that is strong relative to historical estimates (Gurney et al., 2002; Peylin et al., 2013). The results from these models for other time periods (2004-2014, 2001-2004, 1992-1996) and re-evaluation of the TransCom 3 Level 2 and RECCAP results confirm that tropical land carbon fluxes including deforestation have been near neutral for several decades. However, models still have large disagreements on ocean-land partitioning. The fossil fuel (FF) and the atmospheric growth rate terms have been thought to be the best-known terms in the global carbon budget, but we show that they currently limit our ability to assess regional-scale terrestrial fluxes and ocean-land partitioning from the model ensemble.