Collaborative Research: Forced drivers of trends in ocean biogeochemistry: Volcanos and atmospheric carbon dioxide

合作研究：海洋生物地球化学趋势的强制驱动因素：火山和大气二氧化碳

• 批准号: 1948728
• 负责人: Matthew Long
• 金额: $ 6.4万
• 依托单位: University Corporation For Atmospheric Res
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1948728&HistoricalAwards=false
• 关键词: Collaborative; Research; Forced; drivers; trends

The world’s oceans play an important role in the global carbon and oxygen cycles. In addition to their importance in the natural cycling of carbon, the oceans have absorbed approximately 40% of the carbon dioxide that has been emitted by fossil fuel burning. Understanding the processes that cause spatial and temporal variations of ocean carbon and oxygen concentrations is critical to predicting how these ocean cycles will develop into the future. Recent measurement-based estimates and computer models agree that ocean carbon uptake increased significantly in the early 1990s and then slowed over the rest of the decade. Observations and models also indicate significant oxygen variations. One possible driver of these patterns that has not been explored is the influence of large volcanic eruptions, specifically Mount Pinatubo in 1991. With the eruption, small particles were forced to great altitude where they spread through the upper atmosphere, reflected sunlight back to space, and led to a temporary cooling of global climate. This project will explore how this temporary cooling influenced ocean circulation, and air-sea carbon and oxygen exchange, by comparing Earth system model simulations that do and do not include the effects of Mt. Pinatubo’s eruption. Within the framework of NCAR’s Community Earth System Model Large Ensemble (CESM-LE) effort, the team will complete a new experiment that explicitly excludes forcing from Mt. Pinatubo (CESM-LE-NoVolc). By difference from the existing CESM-LE that includes all forcing, the investigators will directly identify the effects of Mt. Pinatubo and put these effects in context with observed carbon and oxygen change. Specifically, they propose to address two hypotheses: Hypothesis 1: Trends in surface fluxes and interior distributions of anthropogenic carbon and oxygen since the 1990s have been significantly impacted by Mt. Pinatubo.Hypothesis 2: After the initial uptake anomaly due to Mt. Pinatubo, thermocline anomalies that are cool and anomalously high in tracers return to the surface. These anomalies suppress air- to-sea fluxes for up to a decade after the eruption. Recent work has also indicated that variability in the growth rate of atmospheric carbon dioxide has a first-order effect on variability of ocean carbon uptake. The investigators will also do preliminary analysis using one new run of the CESM ocean-ice hindcast and a stratified analysis of CMIP6 models to further explore this issue. Specifically, they propose a third hypothesis: Hypothesis 3: By including the seasonal cycle and latitudinal distribution of atmospheric carbon dioxide in simulations, variability of the globally integrated air-sea carbon flux is increased and becomes more comparable to observationally-based estimates. By creating CESM-LE-NoVolc, this work will allow for investigation of the forced impact of Mt. Pinatubo on a wide range of ocean biogeochemical and physical processes. Model runs will be made easily available under the CESM-LE project umbrella. Under this research project, graduate and undergraduate research will be supported. The team will continue to our long-standing efforts to attract underrepresented students to science, and to explain ocean and carbon cycle science to the general public and K-12 students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

世界海洋在全球碳和氧气周期中起着重要作用。除了它们在碳的自然循环中的重要性外，海洋还吸收了大约40％的二氧化碳，这些二氧化碳已被化石燃料燃烧发射。了解导致海洋碳和氧气浓度的空间和暂时变化的过程对于预测这些海洋周期如何发展到未来至关重要。最近的基于测量的估计值和计算机模型同意，海洋碳的吸收在1990年代初显着增加，然后在整个十年的其余时间里放慢了速度。观测和模型还表明氧气变化很大。尚未探索的这些模式的一个可能的驱动因素是大型火山喷发的影响，特别是1991年的皮纳图波山。随着喷发，小颗粒被迫在大气中散布在上层大气中，反射的阳光回到了太空，并导致了全球气候的临时冷却。该项目将通过比较地球系统模型模拟，并不包括Pinatubo山的效果，从而探讨这种临时冷却如何影响海洋循环以及空气碳和氧交换。在NCAR社区地球系统模型大型合奏（CESM-LE）的框架内，团队将完成一个新的实验，该实验明确排除了Pinatubo山（CESM-LE-LE-NOVOLC）的强迫。通过与现有的CESM-LE的差异，包括所有强迫，研究人员将直接识别Pinatubo山的影响，并将这些效果与观察到的碳和氧气变化相同。具体而言，他们建议解决两个假设：假设1：自1990年代以来人为碳和氧的表面通量和内部分布的趋势受到Pinatubo山的显着影响。这些异常抑制喷发后长达十年的空气对海量。最近的工作还表明，大气二氧化碳生长速率的变化对海洋碳吸收变异性具有一阶影响。研究人员还将使用CESM Ocean-Ice Hindcast的一项新运行以及对CMIP6模型的分层分析进行初步分析，以进一步探索此问题。具体而言，他们提出了第三个假设：假设3：通过在模拟中包括季节性周期和大气二氧化碳的纬度分布，全球整合的空气碳通量的变化增加了，并与基于观测的估计值更可比。通过创建CESM-LE-NOVOLC，这项工作将允许Pinatubo山对各种海洋生物地球化学和物理过程的强迫撞击进行投资。在CESM-LE项目的雨伞下，模型运行将易于使用。在该研究项目下，将支持研究生和本科研究。该小组将继续我们长期以来的努力，以吸引代表性不足的学生进入科学，并向公众和K-12学生解释海洋和碳循环科学。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准通过评估来获得的支持。