Testing the New Oceanic Dimethylsulfide (DMS) Stress / Bloom Regime Hypothesis in a Global Coupled Ecosystem-Biogeochemistry Numerical Model

海洋生产和随后通风到大气中的二甲基硫（DMS）已被认为是一个重要的气候调节器，但到目前为止，关闭DMS气候反馈回路的机制一直是定性和经验。 在这个项目中，伍兹霍尔海洋研究所的研究人员将在全球耦合生态系统-海洋地球化学模型中测试一个新的两种制度（压力/水华强迫）假设。这两个政权的概念模型表明，在应力强迫政权，DMS和二甲基磺基丙酸（DMSP，DMS的化学前体）的浓度被迫由物理环境，如浅混合层和高累积剂量的紫外线辐射所产生的应力。相比之下，在水华强迫制度，表面二甲硫醚浓度的变化与传统的DMSP生产浮游植物物种的单物种水华。该项目的具体科学目标是：1）通过将最先进的海洋生态系统/海洋环流模型与物理，光学和生物强制DMS子模型相结合，开发全球海洋硫地球化学模拟。2)评价新出现的两种海洋DMS概念模型（应力强迫水华强迫）捕捉现场表面DMS数据中发现的空间/季节/年际模式的能力。3)利用现有的反应性大气硫化学/气候模型探索DMS气候反馈机制的强度。这一综合研究计划将提供更好的定量估计、动力学理解和海气二甲基硫醚通量变化的建模能力，并对由此产生的大气化学和气候反馈进行评估。建模工作将使研究小组能够（1）创建表面DMS浓度和海气通量的季节性空间分布图，（2）评估应力/水华强迫状态假设的一般性，以及（3）量化海气DMS通量变化导致的直接和间接辐射强迫。通过耦合模拟，他们将确定通过大气层的海气DMS扰动对海洋物理学、生物学和DMS循环的影响，为评估拟议DMS-气候反馈机制的所有相互作用组成部分的强度奠定基础。 考虑到人为气候变化的直接社会相关性，科学界必须努力缩小围绕未来气候预测的相当大的不确定性，包括灾害管理系统气候反馈的存在和程度。如果一切按预期进行，该项目将产生一个数值模型，这将提高我们评估与这种反馈机制相关的非线性的能力，以及它将如何在未来潜在的气候变化情景中发挥作用。该项目产生的模型模拟将通过网络向研究界和公众开放。这项拟议的研究直接解决了美国和国际表面海洋-低层大气研究（SOLAS）倡议的关键目标之一，将利用和促进SOLAS研究活动的社区，并将纳入正在进行的基于NSF和NASA资助的研究计划的结果。最后，该项目将通过支持一名博士后研究人员将联合收割机教学和研究结合起来，并将加强和扩大与其他机构科学家的互动。

The oceanic production and subsequent ventilation to the atmosphere of dimethylsulfide (DMS) has been suggested as an important climate regulator; but to date, the mechanisms for closing the DMS-climate feedback loop have been qualitative and empirical. In this project, researchers at the Woods Hole Oceanographic Institution will test a new two regime (stress / bloom forced) hypothesis in a global coupled ecosystem-biogeochemistry model. This two regime conceptual model suggests that in the stress forced regime, DMS and dimethylsulfoniopropionate (DMSP, the chemical precursor to DMS) concentrations are forced by stress created by the physical environment such as shallow mixed layers and high cumulative doses of ultraviolet radiation. In contrast, in the bloom forced regime, variability in surface DMS concentrations is associated with mono-species blooms of traditional DMSP producing phytoplankton species. The pecific scientific objectives of the project are to: 1) Develop a global ocean sulfur biogeochemistry simulation by integrating a state of the art marine ecosystem / ocean circulation model with a physically, optically, and biologically forced DMS submodel. 2) Evaluate the ability of the emerging two regime ocean DMS conceptual model (stress forced & bloom forced) to capture the spatial / seasonal / interannual patterns found in in situ surface DMS data. 3) Explore the strength of the DMS-climate feedback mechanism utilizing an existing reactive atmospheric sulfur chemistry / climate model. This integrated research plan will provide improved quantitative estimates, dynamical understanding, and modeling capabilities for air-sea DMS flux variability and an assessment of the resulting atmospheric chemistry and climate feedbacks. The modeling efforts will allow the research team to (1) create seasonally resolved spatial maps of surface DMS concentrations and air-sea fluxes, (2) assess the generality of the stress / bloom forced regime hypothesis, and (3) quantify the direct and indirect radiative forcing resulting from changes in air-sea DMS fluxes. Through the coupled simulations, they will determine the impact of air-sea DMS perturbations through the atmosphere and back on ocean physics, biology, and DMS cycling laying the groundwork to assess the strength of all of the interacting components of the proposed DMS-climate feedback mechanism.This research should have several broader impacts. Given the immediate societal relevance of anthropogenic climate change, it is critical that the scientific community attempt to refine the considerable uncertainties surrounding future climate projections, including the existence and magnitude of the DMS-climate feedback. If all goes as expected, the project should yield a numerical model that will increase our ability to assess the non-linearities associated with this feedback mechanism and how it will play out in potential future climate change scenarios. The model simulations resulting from this project will be made openly available to the research community and public via the web. This proposed research directly addresses one of the key objectives of the U.S. and International Surface Ocean - Lower Atmosphere Study (SOLAS) initiative, will leverage and contribute to a community of SOLAS research activities, and will incorporate results from ongoing field based NSF and NASA funded research programs. Finally, this project will combine teaching and research by supporting a postdoctoral researcher and will enhance and expand interactions with scientists at other institutions.