Moored Mixing Measurements at the Equator

赤道上的系泊混合测量

• 批准号: 0424133
• 负责人: James Moum
• 金额: $ 167.27万
• 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: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0424133&HistoricalAwards=false
• 关键词: Moored; Mixing; Measurements; Equator

0424133A fundamental problem in understanding ocean dynamics is our inadequate knowledge of how the ocean is mixed. In turn, this means that numerical models used to predict future climate scenarios cannot properly parameterize oceanic mixing, which is a sensitive component of their computations. This is especially true in equatorial regions, where currents are strong, near-surface waters are stratified, mixing is energetic and complex, and feedbacks to the atmosphere are critical. A series of short process experiments between 1984 and 1991 revealed the qualitative nature of small-scale interactions responsible for generating turbulence and thereby mixing at the equator. Most importantly, these revealed that significant variations in mixing occurred on time scales longer than could possibly be sampled in short ship-borne process experiments. Indeed, there are strong hints that variations in mixing rates-weak mixing prior to the 1992-93 El Nino and strong mixing to conclude the 1997-98 El Nino-contribute positive feedback toward modulating equatorial SST on El Nino/La Nina time scales. New ways to measure mixing on time scales longer than a ship-borne process experiment must be found.A self-contained device to measure temperature microstructure using glassbead thermistors will be designed, build and tested locally before being deployed on a deep-water mooring. The objective is to develop a simple, reliable and affordable device to be readily integrated into existing moorings. Specifically, a suite of 10 devices will be deployed on the TAO mooring at 0 140W for an initial period of 6 months. This deployment will be augmented by 4 days of turbulence profiling at the mooring location. The moored devices will provide the data to determine the turbulent diffusivity of heat (or buoyancy) and hence the turbulent heat flux at each sensor location. By deploying many devices vertically, the vertical divergence of the turbulent heat flux, or the heating rate of a parcel of water due to turbulent mixing will be computed. By deploying over a long time period, the influence of turbulent mixing on sea surface temperature changes associated with long time scale events will be assessed. As well, fundamental aspects of the narrowband internal wave field that are closely linked to turbulence at the equator will be investigated - thereby contributing to our understanding of the physical relationship between mixing and internal waves above the core of the Equatorial Undercurrent. Broader Impacts: The successful demonstration of moored mixing measurements will lead to an affordable and reliable community tool that can be used to obtain long records elsewhere in the ocean. This is especially important in determining the role of vertical mixing as a feedback process to longer time scale events such as El Nino and La Nina. This tool will contribute to the measurement suite available for operational observing systems. Development and scientific analysis will contribute to the training of one graduate student, several summer undergraduate students and College engineers.

0424133a理解海洋动力学的基本问题是我们对海洋如何混合的知识不足。反过来，这意味着用于预测未来气候场景的数值模型无法正确地参数化海洋混合，这是其计算的敏感组成部分。在赤道区域尤其如此，在赤道区域，电流很强，近地面水是分层的，混合充满活力且复杂的，并且对大气的反馈至关重要。 1984年至1991年之间的一系列简短过程实验揭示了负责产生湍流并在赤道上混合的小规模相互作用的定性性质。最重要的是，这些表明，混合的显着变化发生在时间尺度上的时间比短船 - 传播过程实验中可能被采样的时间长。实际上，有很大的提示在1992 - 93年的El Nino和强烈混合之前，混合速率混合的变化是结束1997 - 98年的El Nino-Nino占主导地位的正面反馈，以调节El Nino/La Nina时间尺度上的赤道SST。必须找到比船型工艺过程实验更长的时间尺度混合的新方法。将在部署在深水系列上之前，在本地进行本地设计，构建和测试，以测量使用玻璃面板热敏电阻的温度微观结构的设备。目的是开发一种简单，可靠且负担得起的设备，以便容易整合到现有的系泊设备中。具体而言，将在TAO系泊设备上以0 140W的最初时间为6个月，将部署10个设备的套件。该部署将通过停泊地点进行4天的湍流分析来增强。系泊设备将提供数据以确定热量（或浮力）的湍流扩散，从而在每个传感器位置的湍流通量。通过垂直部署许多设备，将计算湍流磁通的垂直差异，或者由于湍流混合而引起的一块水的加热速率。通过长期部署，将评估湍流混合对与长时间尺度事件相关的海面温度变化的影响。同样，将研究与赤道湍流密切相关的窄带内波场的基本方面，从而有助于我们理解赤道潜流核心上方的混合和内部波之间的物理关系。更广泛的影响：成功演示系泊混合测量结果将导致一种负担得起且可靠的社区工具，可用于在海洋其他地方获得长期记录。这对于确定垂直混合作为反馈过程的作用尤其重要，例如El Nino和La Nina等更长的时间尺度事件。该工具将有助于可用于操作观察系统的测量套件。发展和科学分析将有助于对一名研究生，几个夏季本科生和大学工程师的培训。