Collaborative Research: Oceanic Response to Atmospheric Forcing in the Kuroshio Extension

了解近惯性内波的产生和传播是很重要的，近惯性内波被认为有助于深海混合和维持深海分层。中尺度涡旋和洋流影响近惯性波从混合层到海底的次表层路径，并可能使它们偏转、捕获和聚焦。最近的数值模型支持这些预测，但还有很多工作要做，以了解和验证近惯性波是如何在强电流系统中传播并重新分配能量的。由于黑潮伸展期强烈的海气相互作用，海洋变率可能对偏远地区的风和气候产生潜在影响。特别是，亚热带模态水（STMW）被认为是与气候系统密切相关的大型上层海洋热库。冬季地面混合层的非均匀冷却和加深形成了具有高时空变异性的STMW。该项目将利用作为黑潮延伸系统研究（KESS）和黑潮延伸观测站（KEO）计划的一部分收集的海洋和大气观测资料，调查黑潮地区上层和深海对大气强迫的响应。该项目将重点研究风产生的近惯性运动，它们传播和消散的方式和位置，以及它们如何直接影响混合层和STMW的质量和热量收支。2004年5月部署的KESS阵列？2006年6月，包括水下系泊，系泊剖面仪和流速仪，以及配备近海底压力和电流传感器的反向回声测深仪。KEO是一个系泊水面浮标，于2004年首次作为KESS的一部分部署，现在是持续海洋气候观测系统的一部分。KESS阵列由于其垂直、水平、时间分辨率和空间覆盖范围的结合而非常适合进行这些研究。从该项目中获得的理解在测试气候模式中混合的参数化和近惯性波如何被强电流系统携带、捕获和集中的理论概念方面具有广泛的适用性。与海气相互作用形成模态水有关的过程和反馈可能在强风吹过充满锋面和中尺度涡旋的海洋的地区很重要，例如在南大洋周围。这些过程对气候变率非常重要，是气候变率与预测（CLIVAR）项目的重点。KESS从计划阶段就被纳入CLIVAR，其研究结果补充了其他美国CLIVAR研究（例如CLIMODE、SAMFLOC和DIMES）。随着全球海洋模式和风场的分辨率越来越高，从而可以直接模拟近惯性波，因此有资料证明海洋响应的例子，特别是强中尺度流场中的近惯性波对偶发性大气强迫的响应，将是非常重要的。

It is important to understand the generation and propagation of near-inertial internal waves, which are thought to contribute to deep-ocean mixing and maintenance of the abyssal stratification. Mesoscale eddies and currents affect the subsurface pathways of near-inertial waves from the mixed layer to the sea floor, and may deflect, trap, and focus them. Recent numerical models support these predictions, but much work remains to understand and verify how near inertial waves propagate to redistribute their energy in and under strong current systems. Due to the intense air-sea interactions in the Kuroshio Extension, ocean variability can potentially affect the winds and climate in remote regions. In particular, the subtropical mode water (STMW) has been considered as a large upper-ocean heat reservoir closely linked to the climate system. The non-uniform cooling and deepening of the surface mixed layer forms the STMW during winter with high variability in space and time. This project will investigate the upper and deep ocean response to atmospheric forcing in the Kuroshio region using oceanic and atmospheric observations collected as part of the Kuroshio Extension System Study (KESS) and the Kuroshio Extension Observatory (KEO) programs. The project will focus on the generation of near-inertial motions from the wind, how and where they propagate and dissipate, and how they directly affect the mass and heat budget of the mixed layer and STMW. The KESS array, deployed during May 2004?June 2006, comprised subsurface moorings with moored profilers and current meters, and inverted echo sounders equipped with near-bottom pressure and current sensors. KEO, a moored surface buoy, was first deployed in 2004 as part of KESS and is now part of the sustained ocean climate observing system. The KESS array is uniquely suited to conduct these studies due to its combination of vertical, horizontal, and temporal resolution and extent of spatial coverage. Understanding gained from this project has broad applicability in testing parameterizations of mixing in climate models and theoretical concepts of how near-inertial waves can be carried, trapped, and concentrated by strong current systems. The processes and feedbacks related to mode water formation by air-sea interaction are likely to be important in regions where strong winds blow over an ocean full of fronts and mesoscale eddies such as around the Southern Ocean. These processes are of great importance for climate variability, the focus of the Climate Variability and Prediction (CLIVAR) program. KESS has been included in CLIVAR from its planning phase and its findings complement other U.S. CLIVAR studies (e.g., CLIMODE, SAMFLOC, and DIMES). As global ocean models and wind fields achieve increasingly high resolution, allowing direct simulation of near-inertial waves, it will be important to have documented examples of the oceanic response in particular of the near-inertial waves in a strong mesoscale flow field to episodic atmospheric forcing.