Testing global ocean carbon cycle models using measurements of atmospheric O2 and CO2 concentration
Testing global ocean carbon cycle models using measurements of atmospheric O2 and CO2 concentration
复制标题
使用大气 O2 和 CO2 浓度测量测试全球海洋碳循环模型
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
K. Caldeira
中科院分区：
文献类型：
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作者：
B. Stephens;R. Keeling;M. Heimann;K. Six;R. Murnane;K. Caldeira
我们提出了一种通过测量大气中O2和CO2浓度来测试全球海洋碳循环模型性能的方法。我们结合这些测量来定义一个示踪剂，大气势氧（APO≈O2 + CO2），这是相对于陆地光合作用和呼吸是保守的。然后，我们将APO观测值与使用海洋-模式海气通量和化石燃料燃烧估算值作为下边界条件的大气输送模式的模拟结果进行比较。我们在一个南北样带的10个站点观测了CO2、O2和APO的年平均浓度。APO观测结果显示，半球间梯度向北递减。我们使用来自普林斯顿海洋生物地球化学模型、汉堡海洋碳循环模型和劳伦斯利弗莫尔海洋生物地球化学模型的空气-海洋CO2、O2和N2通量来驱动TM2大气输送模型。组合模式预测的年平均APO的纬度变化与观测值有明显差异。这三种模式都明显低估了半球间APO的差异，这表明它们低估了海洋中O2和CO2的净向南输送总量。模式-观测比较中的不确定性包括与大气测量、大气输送模式以及海洋模式的物理和生物成分有关的不确定性。海洋模式的物理成分可能存在缺陷，而这些缺陷以前曾被认为是造成南大洋异常大的热通量的原因，这可能是造成与APO观测结果不一致的原因之一。这些不足包括对亚格网尺度等压轴涡旋混合参数化不足、缺乏亚格网尺度垂直对流、南极海冰形成过多以及对主温跃层垂直扩散系数的过高估计。
We present a method for testing the performance of global ocean carbon cycle models using measurements of atmospheric O2 and CO2 concentration. We combine these measurements to define a tracer, atmospheric potential oxygen (APO ≈ O2 + CO2), which is conservative with respect to terrestrial photosynthesis and respiration. We then compare observations of APO to the simulations of an atmospheric transport model which uses ocean‐model air‐sea fluxes and fossil fuel combustion estimates as lower boundary conditions. We present observations of the annual‐average concentrations of CO2, O2, and APO at 10 stations in a north‐south transect. The observations of APO show a significant interhemispheric gradient decreasing towards the north. We use air‐sea CO2, O2, and N2 fluxes from the Princeton ocean biogeochemistry model, the Hamburg model of the ocean carbon cycle, and the Lawrence Livermore ocean biogeochemistry model to drive the TM2 atmospheric transport model. The latitudinal variations in annual‐average APO predicted by the combined models are distinctly different from the observations. All three models significantly underestimate the interhemispheric difference in APO, suggesting that they underestimate the net southward transport of the sum of O2 and CO2 in the oceans. Uncertainties in the model‐observation comparisons include uncertainties associated with the atmospheric measurements, the atmospheric transport model, and the physical and biological components of the ocean models. Potential deficiencies in the physical components of the ocean models, which have previously been suggested as causes for anomalously large heat fluxes out of the Southern Ocean, may contribute to the discrepancies with the APO observations. These deficiencies include the inadequate parameterization of subgrid‐scale isopycnal eddy mixing, a lack of subgrid‐scale vertical convection, too much Antarctic sea‐ice formation, and an overestimation of vertical diffusivities in the main thermocline.