mCDR 2023: Multiscale observing system simulation experiments for iron fertilization in the Southern Ocean, Equatorial Pacific, and Northeast Pacific

为了应对气候变化的预期影响，除了减少排放外，还需要积极地从大气中清除二氧化碳。越来越多的人一致认为，至少社会对二氧化碳去除（CDR）的部分需求将不得不来自海洋。天然浮游植物种群的铁施肥是海洋CDR中更有前途的方法之一，但关键问题仍然存在，包括：它有多有效？碳会被封存多久？我们如何测量它？对海洋生态系统的预期和意外后果是什么？过去的海洋铁施肥实验提供了关于短期反应的重要信息，但大多数研究都不够长，也不够大，无法测量流向深海的碳通量的增加。为了解决设计更大规模和更长时间的实地试验所需的问题，该项目将使用海洋模型在被视为铁施肥可能目标的海洋三个关键区域进行观测系统模拟实验（OSSEs）：南大洋、赤道太平洋和亚北极太平洋。更广泛的影响包括通过提高对与地球气候相关的关键物理和生物过程的理解来造福社会，并支持学生的研究。该项目由国家海洋和大气管理局通过国家海洋学伙伴计划共同支持。osse将基于两个最先进的全球海洋生物地球化学模型，具有旋转（0.1-0.125°）分辨率：NCAR群落地球系统模型与海洋生物地球化学库（CESM-MARBL）和GFDL模块化海洋模型6与碳，海洋生物地球化学和低营养物模型（MOM6-COBALT）。高分辨率嵌套区域海洋模拟系统（ROMS）模型将嵌入到这两个全球模型中，以提供三个感兴趣区域的高能涡旋和锋面特征的真实表示。这两个母模型的“集合”将使研究小组能够评估结果对潜在生物地球化学公式的敏感性。有限区域铁施肥试验的远场效应将在全球模式的类似有限区域施肥试验中进行评估。在目标高海拔地区大面积施肥的全球模型的额外运行将解决大规模铁富集的有效性，促进全球观测网络的OSSEs。这些仅针对全球海洋的模拟运行时间尽可能长（30年）。为了研究每年十亿吨碳排放规模下区域铁施肥的长期效果和影响，将以粗分辨率运行100年的全耦合地球系统模型（GFDL的ESM4和NCAR的CESM2）。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In order to combat the expected impacts of climate change, active removal of carbon dioxide from the atmosphere is needed in addition to emissions reductions. There is a growing consensus that at least some of society’s needs for carbon dioxide removal (CDR) will have to come from the ocean. Iron fertilization of natural phytoplankton populations is among the more promising means for ocean-based CDR, yet key questions remain, including: How effective is it? How long will the carbon be sequestered? How can we measure it? What are the intended and unintended consequences to marine ecosystems? Past ocean iron fertilization experiments have provided important information about short-term responses, but most studies were not long or large enough to measure an increase in carbon flux to the deep sea. To address the questions needed to design larger and longer field trials, this project will use ocean models to run Observing System Simulation Experiments (OSSEs) in three key regions of the ocean that are seen as likely targets for iron fertilization: the Southern Ocean, the Equatorial Pacific, and the Subarctic Pacific. Broader impacts include benefits to society via improved understanding of key physical and biological processes relevant to earth’s climate, and support of students in the research. This project is being jointly supported by the National Oceanic and Atmospheric Administration, through the National Oceanographic Partnership Program.The OSSEs will be based on two state-of-the-art global ocean biogeochemical models with eddying (0.1-0.125°) resolution: the NCAR Community Earth System Model with the Marine Biogeochemistry Library (CESM-MARBL) and the GFDL Modular Ocean Model 6 with the Carbon, Ocean Biogeochemistry and Lower Trophics model (MOM6-COBALT). High resolution nested Regional Ocean Modeling System (ROMS) models will be embedded within both global models to provide realistic representation of the energetic eddies and fronts characteristic of the three regions of interest. This “ensemble” of two parent models will allow the team to assess the sensitivity of the results to the underlying biogeochemical formulation. Far-field effects of the limited-area iron fertilization experiments will be assessed with analogous limited-area fertilization experiments in the global models. Additional runs of the global models with fertilization over large areas of the target HNLC regions will address the efficacy of iron enrichment at scale, facilitating OSSEs for a global observing network. These global ocean-only simulations run for as long as practical (30 years). To address the long-term efficacy and effects of regional iron fertilization at the scale of gigatons of carbon per year, fully coupled earth system models (ESM4 at GFDL and CESM2 at NCAR) will be run for 100 years at coarse resolution.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.