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.

月球周围围绕地球的变化会影响气候吗？许多研究与LNC的物理气候和生物地球化学变量的观察结果相关。尤其是在北太平洋及其周围的昼夜潮汐成分很强的地方，这些观察结果表明LNC对温度，海洋和大气循环以及生物地球化学周期的重要影响。没有LNC强迫的模型模拟显示北太平洋等太平洋衰老振荡等纪念际变异性的强大内部模式。 LNC强迫可以通过（1）将可变性转移到BideCadal频率范围，（2）产生共振或（3）同步其相位。该项目将通过海洋混合的调节和随之而来的对温度和际气候变化的方式的影响来测试潮汐中的LNC振荡与气候中的bidecadal振荡相关的假设。全球潮汐混合的全球性参数化的参数化已经在全球范围内实现了潮气的潮流模型。 模型。该参数化包括一个新的子网格尺度测深的方案，并分别考虑了四个潮汐成分（M2，S2，K1和O1）及其由于LNC而引起的时间变化。该模型将用于模拟潮汐混合的LNC振荡对北太平洋际变化的潮汐扩散，温度，海洋和大气循环的影响。模型结果将进行分析，并将其与现有观察结果进行比较。卫星高度计数据（现在已在一个完整的LNC上可用）将进行分析，目的是改善潮汐耗散估计值，潮汐混合参数化以及对预压能量损失的机制的理解：肯定对气候变化的强迫机制对预测的强度重要性是重要的。近几十年来，在气候模型中识别和结合气溶胶，太阳和火山变异性的影响方面取得了很多进展。然而，尽管有大量文献描述了在各种气候变量中对18。6年的月球结节周期的观察结果，但其效果并未包括在气候模型中。该项目有可能改善衰老时间尺度的气候预测，尤其是在北太平洋地区。 IPCC评估报告中使用的模型之一将对CCSM4中的海洋混合实施农历淋巴结周期对海洋混合的影响，将有助于这些有关重大政策相关性的国际报告。模型代码将提供给大型用户社区。北太平洋际变异性会影响生态系统和社会。例如，在北美西海岸的大陆货架上的低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利福尼亚州当前大型海洋生态系统和该地区许多商业重要渔业的生活系统。三个具有不同专业知识的PI团队之间的合作，背景（全球气候建模，潮汐，耦合的物理生物学区域海洋建模）和性别多样性将得到培养。博士后研究人员将接受有关气候建模和数据分析的培训，并给予教学机会。一名本科生将通过暑期实习。在2014年美国地球物理联盟的秋季会议上，将组织有关北太平洋际变异性的会议。