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循环中发挥着重要作用，除了在碳的自然循环中发挥着重要作用外，海洋还吸收了化石燃料燃烧排放的约 40% 的二氧化碳。导致海洋碳和氧浓度的空间和时间变化对于预测这些海洋循环将如何发展到未来至关重要。最近基于测量的估计和计算机模型一致认为，海洋碳吸收在 20 世纪 90 年代初期显着增加，然后在 20 世纪 90 年代初放缓。休息观测和模型还表明，这些模式的一个可能的驱动因素尚未被探索，那就是大型火山喷发的影响，特别是 1991 年的皮纳图博火山。随着火山喷发，小颗粒被迫到达很高的高度。它们穿过高层大气，将阳光反射回太空，并导致全球气候暂时变冷。该项目将通过比较地球系统模型模拟，探讨这种暂时变冷如何影响海洋环流以及海气碳和氧交换。在 NCAR 的社区地球系统模型大型集合 (CESM-LE) 工作框架内，该团队将完成一项新实验，明确排除皮纳图博山喷发的影响 (CESM-LE)。与包括所有强迫在内的现有 CESM-LE 不同，研究人员将直接识别皮纳图博山的影响，并将这些影响与观测到的碳和氧放在一起。具体来说，他们提出解决两个假设： 假设 1：自 20 世纪 90 年代以来，人为碳和氧的表面通量和内部分布趋势受到皮纳图博山的显着影响。假设 2：在皮纳图博山造成的最初吸收异常之后，温度较低且示踪剂含量异常高的温跃层异常返回地面，这些异常会抑制空气到海洋的通量。最近的研究还表明，大气二氧化碳增长率的变化对海洋碳吸收的变化具有一级影响。研究人员还将使用新一轮的 CESM 进行初步分析。具体来说，他们提出了第三个假设：假设3：通过在模拟中纳入大气二氧化碳的季节循环和纬度分布，全球的变化性可以通过海洋冰后报和CMIP6模型的分层分析来进一步探讨。通过创建CESM-LE-NoVolc，综合空气-海洋碳通量增加，并且与基于观测的估计更具可比性，这项工作将允许调查皮纳图博山对广泛的海洋生物地球化学和物理过程的强制影响。在 CESM-LE 项目的保护下，模型运行将很容易进行，该团队将继续我们长期以来的努力，吸引代表性不足的学生进入科学领域，并解释海洋。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。