Testing model estimates of recent ocean carbon uptake and deoxygenation using atmospheric and oceanic data

使用大气和海洋数据测试近期海洋碳吸收和脱氧的模型估计

• 批准号: 1130976
• 负责人: Ralph Keeling
• 金额: $ 48.06万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-10-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1130976&HistoricalAwards=false
• 关键词: Testing; model; estimates; recent; ocean

Model studies suggest that global warming may reduce the ocean uptake of CO2 via changes in ocean circulation and carbon chemistry and lead to reductions of dissolved O2 in the ocean interior, causing an expansion of O2 minimum zones. These processes are possibly already underway in response to warming and wind changes over the past few decades. In this project, researchers at the Scripps Institution of Oceanography will test ocean model simulations of air-sea O2 and CO2 exchange using an approach emphasizing constraints from combined measurements of atmospheric O2/N2 ratio and CO2 concentrations and ocean measurements of chloro-fluorocarbons (CFCs). The approach is based on computing tracer "atmospheric potential oxygen" (APO), which is effectively the weighted sum O2 + 1.1CO2. By construction, APO is insensitive to land biospheric exchanges of CO2 and O2. Observations by the Scripps and Princeton O2 programs show that APO has decreased over the past two decades at a precisely measured rate. Two components of the APO decrease are well understood: (1) a fossil-fuel component and (2) a component related to uptake of anthropogenic CO2 by the oceans, which can be estimated based on ocean observations of CFCs. These two components can both be precisely quantified, and together appear to overestimate the observed APO decrease. The residual APO change constrains the air-sea exchanges of O2 and CO2 not counted as anthropogenic, i.e. due to climate impacts on the oceans. The APO trend is thus directly relevant to quantifying ongoing changes in ocean CO2 and O2. A core activity of this proposal will involve developing and applying data targets for model validation based on the observed APO changes. Working closely with four ocean modeling groups, the Scripps researchers will acquire output of model runs that simulate air-sea exchange of O2 and CO2 over the past few decades in response to climate changes and rising CO2. They will test not only the ability of the models to account for the long-term trends in APO but also for the seasonal cycles, which relate to the processes controlling O2 exchange at middle and high latitudes. Broader Impacts: This work will help to solidify the scientific understanding of two looming and related environmental threats: climate amplification of rising CO2 and ocean deoxygenation. It will also complement ongoing measurement activities of the Scripps O2 program by sustaining a small but viable modeling component. The project will enable dissemination of cutting edge research to the public at large through public presentations and will help foster young talent through support for a young scientist and a graduate student.

模型研究表明，全球变暖可能会通过海洋环流和碳化学的变化减少海洋对二氧化碳的吸收，并导致海洋内部溶解的O2减少，导致O2最小区的扩大。这些过程可能已经在进行中，以应对过去几十年的变暖和风的变化。在这个项目中，斯克里普斯海洋学研究所的研究人员将使用一种强调大气O2/N2比率和CO2浓度的综合测量和海洋氯氟烃测量的限制的方法，测试海洋模型模拟的海气O2和CO2交换。该方法基于计算示踪剂“大气潜氧”（APO），其实际上是O2 + 1.1CO2的加权和。通过构造，APO对陆地生物圈的CO2和O2交换不敏感。斯克里普斯和普林斯顿O2项目的观测表明，在过去的二十年里，载脂蛋白O以精确测量的速度下降。载脂蛋白O减少的两个组成部分是众所周知的：（1）化石燃料组成部分和（2）与海洋吸收人为CO2有关的组成部分，这可以根据海洋对CFC的观测来估计。这两种成分都可以精确定量，并且一起似乎高估了观察到的APO降低。剩余的载脂蛋白O的变化限制了O2和CO2的海气交换，而不计入人为因素，即由于气候对海洋的影响。因此，APO趋势与量化海洋CO2和O2的持续变化直接相关。该提案的核心活动将涉及根据观测到的载脂蛋白O变化制定和应用数据目标，以进行模型验证。与四个海洋建模小组密切合作，斯克里普斯的研究人员将获得模型运行的输出，这些模型模拟了过去几十年来为应对气候变化和二氧化碳上升而进行的O2和CO2的海气交换。他们不仅将测试模型解释APO长期趋势的能力，还将测试与控制中高纬度O2交换的过程有关的季节周期的能力。更广泛的影响：这项工作将有助于巩固对两个迫在眉睫的相关环境威胁的科学认识：二氧化碳上升的气候放大和海洋脱氧。它还将通过维持一个小而可行的建模组件来补充斯克里普斯O2计划正在进行的测量活动。该项目将通过公开演示向广大公众传播尖端研究成果，并将通过支持一名青年科学家和一名研究生帮助培养青年人才。