Mixing Across the Pacific Equatorial Cold Tongue

跨越太平洋混搭赤道冷舌

• 批准号: 1256620
• 负责人: James Moum
• 金额: $ 199.54万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-03-15 至 2019-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1256620&HistoricalAwards=false
• 关键词: Mixing; Across; Pacific; Equatorial; Cold

The cold tongue in the Equatorial Pacific is an expansive region of net ocean heat uptake. Maintaining these cool sea surface temperatures requires a combination of subsurface mixing or lateral/vertical advection to transport surface heat downward. Whether mixing plays the dominant role is not yet clear, but it has been established that a rich set of fluid dynamical processes in the upper equatorial ocean drives intense turbulence. Evidence from limited observations on the Equator at 140W during the passage a Tropical Instability Wave (TIW) revealed a ten-fold increase in subsurface turbulent heat flux, sufficient to cool surface waters by 2 degree Celsius per month. This suggests the possibility that mixing alone could maintain the equatorial cold tongue, a conjecture supported by climatological evidence that sea surface cooling is enhanced by Tropical Instability Waves.Intellectual Merit: Since 2005, moored mixing measurements on the Equator at 140W using a novel self-contained instrument (chi-pod) provide a more complete temporal assessment of the mixing. These moored records indicate not only considerable variability on short time scales but also significant seasonal variations in turbulence levels that are roughly 90-180° out-of-phase with the annual cycle in Sea Surface Temperature. However, the time-varying part of the spatial structure is completely unknown. Strong cross-equatorial gradients in currents, temperature and salinity imply that gradients in mixing are likely to be strong as well. At present, it is impossible to distinguish temporal cycles from spatial gradients.This project will expand the measurements of mixing on the Tropical Atmosphere-Ocean mooring array along the equator between 140W and 95W. Each of these 4 moorings will be outfitted with 5 chi-pods and the analysis of the data obtained from these moorings will be supplemented by existing data from past process experiments at 140W and a detailed, complementary process experiment at 102.5W. The main goals of he project are to quantify (1) the time- and spatially-varying structure of mixing along and across the cold tongue; (2) the role of mixing in maintaining the cold tongue; (3) the role of TIWs in equatorial mixing; and (4) the role of turbulence in consuming TIW energy.Broader Impacts: A post-doctoral associate will participate in a broad analysis of the Tropical Atmosphere Ocean Array and mixing measurements and be trained in equatorial dynamics. College graduate students will participate in the process experiment. Undergraduate engineering students will be employed in the summer months to help with both electronics and mechanical construction and testing of instrumentation. An undergraduate atmospheric science student will be employed in the summer of 2013 to review and document archived data from the Mary's Peak webcam (http://marycam.coas.oregonstate.edu/index.html) for public dissemination.This project complements ongoing theoretical analyses of Tropical Instability Waves conducted by the lead investigators and several colleagues. Data obtained in the project will be shared with the Climate Process Team on ocean mixing and become part of the archived data sets of the Tropical Atmosphere Ocean Array Program managed by the National Oceanic and Atmospheric Administration. This project is a contribution to the U.S. CLIVAR (CLImate VARiability and predictability) Porgram.

赤道太平洋中的冷舌是净海量吸收的额外区域。保持这些凉爽的海面温度需要地下混合或横向/垂直广告的结合，以向下传输表面加热。混合是否扮演主导作用尚不清楚，但是已经确定，在上方海洋上，一组丰富的流体动态过程驱动着强烈的湍流。在通道中，对赤道的有限观察结果有限，热带不稳定性波（TIW）表明地下湍流磁通量增加了十倍，足以使每月摄氏2摄氏度冷却地表水。这表明单独混合可以维持赤道冷舌的可能性，这是一个由气候学证据支持的猜想，即热带不稳定性波增强了海面冷却，以增强海面冷却，以自2005年以来，自2005年以来，使用新颖的自容器仪表（CHI-POD）在140W时在140W上对赤道进行了备用的混合测量，可提供更完整的临时评估。这些停泊的记录不仅表明在短时间尺度上的考虑变异性，还表明湍流水平的季节性变化大约为90-180°，并且海面温度的年周期。但是，空间结构的时变部分是完全未知的。电流，温度和盐度的强跨备梯梯度表明，混合的梯度也可能很强。目前，不可能将临时循环与空间梯度区分开。该项目将扩大在140W和95W之间的热带大气 - 海系系泊阵列上混合的测量值。这4个系泊设备中的每一个都将配备5个CHI-POD，从这些系泊设备获得的数据分析将通过过去140W的过去过程实验的现有数据补充，并在102.5W时进行了详细的完整过程实验。 HE计划的主要目标是量化（1）沿着冷舌的混合的时间和空间变化的结构； （2）混合在保持冷舌中的作用； （3）TIWS在相等混合中的作用； （4）湍流在消耗TIW能量中的作用。Broader的影响：博士后助理将参与对热带气氛海洋阵列和混合测量的广泛分析，并接受等效动态的培训。大学生将参加过程实验。本科工程专业的学生将在夏季雇用，以帮助电子设备，机械构建和仪器测试。一名本科大气科学专业的学生将在2013年夏季雇用，以审查和记录玛丽峰网络摄像头（http://marycam.coas.oregonstate.edu/index.html）的归档数据，以进行公开销售。这项项目完成了持续的理论分析，该项目的持续理论分析了热带实例的领导者的导演研究员和几项领导者和几项研究。该项目中获得的数据将与气候过程团队共享有关海洋混合的气候团队，并成为由国家海洋和大气管理局管理的热带气氛海洋阵列计划的存档数据集的一部分。该项目是对美国Clivar（气候变异性和可预测性）孔隙的贡献。