Quantifying the Effect of the Lunar Nodal Tide on North Pacific Climate Variability

量化月交点潮汐对北太平洋气候变化的影响

• 批准号: 1260680
• 负责人: Andreas Schmittner
• 金额: $ 23.48万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-03-15 至 2018-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1260680&HistoricalAwards=false
• 关键词: Quantifying; Effect; Lunar; Nodal; Tide

Can variations of the moon's orbit around the earth affect climate? Numerous studies have associated bidecadal variability in observations of physical climate and biogeochemical variables with the LNC. Particularly in and around the North Pacific, where diurnal tide constituents are strong, these observations point towards a significant influence of the LNC on temperatures, oceanic and atmospheric circulation and biogeochemical cycles. Model simulations without LNC forcing show strong internal modes of decadal variability in the North Pacific such as the Pacific Decadal Oscillation. LNC forcing could modulate these internal modes by (1) shifting variability into the bidecadal frequency range, (2) generate resonance, or (3) synchronize their phases. This project will test hypotheses relating LNC oscillations in tides to bidecadal variability in climate via modulations of ocean mixing and attendant effects on temperatures and modes of decadal climate variability.A globally consistent parameterization of tidal mixing, that has already been tested in a climate model of intermediate complexity and shown to lead to climatically significant sea surface temperature anomalies, will be implemented in a comprehensive global climate model. This parameterization includes a new scheme of sub-grid scale bathymetry and separately considers four tidal constituents (M2, S2, K1 and O1) and their temporal variations due to the LNC. The model will be used to simulate the effects of LNC oscillations of tidal mixing on diapycnal diffusivities, temperatures, oceanic and atmospheric circulation, and modes of decadal variability in the North Pacific. Model results will be analyzed and compared to existing observations. Satellite altimeter data, now available over one full LNC, will be analyzed with the goal to improve tidal energy dissipation estimates, tidal mixing parameterizations, and the understanding of mechanisms of barotropic energy loss.Broader Impacts:
Understanding forcing mechanisms of climate change is critically important for decadal climate predictability. In recent decades much progress has been made in identifying and incorporating effects of aerosols, solar and volcanic variability in climate models. However, despite a considerable literature describing observations of the 18.6-year lunar nodal cycle in various climate variables its effect is not included in climate models. This project has the potential to improve climate predictions on decadal time scales particularly in the North Pacific region. Implementing the effect of the lunar nodal cycle on ocean mixing in CCSM4, which is one of the models used by the IPCC assessment reports, will contribute to these international reports of significant policy relevance. The model code will be made available to the large user community. Decadal variability in the North Pacific affects ecosystems and societies. Improved predictability of hypoxic events on the continental shelf of the west coast of North America, for example, may benefit society as these events affect living systems in the California Current Large Marine Ecosystem and many commercially important fisheries in the region. Collaboration between a team of three PIs with different expertise, background (global climate modeling, tides, coupled physical- biological regional ocean modeling) and gender diversity will be fostered. A postdoctoral researcher will be trained in climate modeling and data analysis and given teaching opportunities. An undergraduate student will participate through a summer internship. A session on decadal variability in the North Pacific will be organized at the 2014 Fall Meeting of the American Geophysical Union.

月球绕地球轨道的变化会影响气候吗？许多研究将物理气候和生物地球化学变量观测值的十年间变化与 LNC 联系起来。特别是在北太平洋及其周边地区，那里的昼夜潮汐成分很强，这些观测结果表明，LNC 对温度、海洋和大气环流以及生物地球化学循环具有重大影响。没有 LNC 强迫的模型模拟显示了北太平洋年代际变化的强烈内部模式，例如太平洋年代际振荡。 LNC 强迫可以通过以下方式调制这些内部模式：(1) 将变异性转移到二十年代频率范围内，(2) 产生共振，或 (3) 同步它们的相位。该项目将通过调节海洋混合以及对温度和十年间气候变率模式的随之影响，测试潮汐中的 LNC 振荡与十年间气候变率相关的假设。潮汐混合的全球一致参数化已在中等复杂性的气候模型中进行了测试，并被证明会导致气候显着的海面温度异常，将在综合全球气候中实施 模型。该参数化包括亚网格尺度测深的新方案，并分别考虑四个潮汐成分（M2、S2、K1 和 O1）及其由 LNC 引起的时间变化。该模型将用于模拟潮汐混合的 LNC 振荡对北太平洋二重扩散率、温度、海洋和大气环流以及年代际变化模式的影响。模型结果将被分析并与现有观测结果进行比较。卫星高度计数据现已通过一个完整的 LNC 提供，将进行分析，目的是改进潮汐能量耗散估计、潮汐混合参数化以及对正压能量损失机制的理解。更广泛的影响：了解气候变化的强迫机制对于十年间气候的可预测性至关重要。近几十年来，在识别气溶胶、太阳和火山变化的影响并将其纳入气候模型方面取得了很大进展。然而，尽管有大量文献描述了 18.6 年月交点周期在各种气候变量中的观测结果，但其影响并未包含在气候模型中。该项目有潜力改善十年时间尺度的气候预测，特别是在北太平洋地区。在 CCSM4（IPCC 评估报告使用的模型之一）中实施月交点周期对海洋混合的影响，将为这些具有重要政策相关性的国际报告做出贡献。模型代码将提供给广大用户社区。北太平洋的年代际变化影响着生态系统和社会。例如，提高北美西海岸大陆架缺氧事件的可预测性可能会使社会受益，因为这些事件会影响加州海流大型海洋生态系统的生命系统以及该地区许多具有重要商业意义的渔业。将促进由三名具有不同专业知识、背景（全球气候模型、潮汐、物理-生物耦合区域海洋模型）和性别多样性的 PI 组成的团队之间的合作。博士后研究员将接受气候建模和数据分析方面的培训，并获得教学机会。本科生将通过暑期实习参与。美国地球物理联盟 2014 年秋季会议将组织一次关于北太平洋年代际变化的会议。