Mixing Across the Pacific Equatorial Cold Tongue

赤道太平洋的冷舌是一个广阔的净海洋热吸收区。保持这些凉爽的海面温度需要地下混合或横向/垂直平流的组合，以向下输送表面热量。混合是否起主导作用尚不清楚，但已经确定，赤道海洋上部丰富的流体动力学过程驱动了强烈的湍流。在热带不稳定波（TIW）通过期间，在140 W的赤道上进行的有限观测表明，次表层湍流热通量增加了10倍，足以使表面沃茨每月冷却2摄氏度。这表明的可能性，混合单独可以保持赤道冷舌，气候学证据支持的推测，海面冷却是由Tropical Instability Waves.Intellectual Merit增强：自2005年以来，停泊在赤道上的混合测量在140 W使用一种新的自包含的仪器（chi-pod）提供了一个更完整的时间评估的混合。这些系泊记录不仅表明在短时间尺度上有相当大的变化，而且还表明湍流水平有显著的季节性变化，与海表温度的年周期相差约90-180°。然而，空间结构的时变部分完全未知。洋流、温度和盐度的强烈跨赤道梯度意味着混合梯度也可能很强。目前还无法区分时间周期和空间梯度，本项目将扩大对热带大气-海洋系泊阵列沿着赤道在140 W和95 W之间混合的测量。这4个系泊设备中的每一个都将配备5个chi-pod，从这些系泊设备中获得的数据分析将由过去在140 W下进行的工艺实验的现有数据和102.5 W下进行的详细补充工艺实验进行补充。该项目的主要目标是量化（1）沿沿着和穿过冷舌的混合的时间和空间变化结构;（2）混合在维持冷舌中的作用;（3）TIW在赤道混合中的作用;以及（4）湍流在消耗TIW能量中的作用。一名博士后助理将参加对热带大气海洋阵列和混合测量的广泛分析，并接受赤道动力学方面的培训。大学研究生将参加工艺实验。本科工程专业的学生将在夏季就业，以帮助电子和机械结构和仪器测试。2013年夏天，将雇用一名大气科学本科生，审查和记录玛丽峰网络摄像头（http：//marycam.coas.oregonstate.edu/index.html）的存档数据，供公众传播。该项目获得的数据将与海洋混合气候进程小组分享，并成为国家海洋和大气管理局管理的热带大气海洋阵列方案存档数据集的一部分。该项目是对美国CLIVAR（气候变化和可预测性）的贡献。

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.