Decadal Upper Ocean Variability in the North Pacific: Mechanisms, Impact and Prediction

近年来，中纬度北太平洋的年代际变率由于其对海洋生态系统和北美大陆气候异常的影响而受到相当大的关注。虽然有零散的证据表明，海洋动力学有助于增加北太平洋中纬度海洋-大气系统在十年时间尺度上的变化和持续性，但仍然缺乏对该系统如何运作的详细了解。为了提高对中纬度太平洋气候变率的预测能力，更好地了解上层海洋动力和热力过程的相互作用是至关重要的。由于行星β效应，风应力引起的上层海洋异常倾向于向西传播并在黑潮延伸区积累。黑潮延伸区将温暖的热带海水输送到中纬度地区，也是最大的海气热交换及其变化发生的地方。西边界海流环流变化的非线性性质可使随时间变化的上层海洋信号进一步复杂化。在这项研究中，Qiu博士和他的同事们基于现有的现场/卫星观测和高分辨率OGCM后报输出，研究了观测到的上层海洋变化的过程。该建议的科学目标是：（1）从上层海洋动力和热力过程相互作用的角度全面描述中纬度北太平洋的年代际变化;（2）发展关于海洋动力在决定海表温度变化中的作用的可检验的假说;黑潮延伸系统是地球气候系统的重要组成部分，特别是北太平洋海盆，它的存在对气候系统的研究具有重要意义。它对中纬度风暴和北太平洋海洋生态系统的强度和轨迹的影响，以及它对美国西北海岸天气模式的影响，具有重要的社会意义。本研究旨在更好地了解海洋动力学在决定北太平洋气候系统十年和更长时间尺度变率中的作用。这种改进的理解可能会扩大我们预测十年海洋状态的能力。虽然研究的重点是具体的KE系统，许多科学问题，如斜压Rossby波的海洋调整的作用，内循环环流的变化，西部边界流出和底部地形之间的相互作用，以及上层海洋环流变化对区域SST的影响，适用于其他西部边界流系统以及。更好地了解KE系统的变化可以作为一个有用的步骤，阐明海洋的中纬度海气耦合的作用。

Decadal variability in the midlatitude North Pacific Ocean has received considerable attention in recent years because of its impact upon the marine ecosystems and the weather anomalies over the North America continent. While scattered evidence exists suggesting the ocean dynamics works to contribute to an increase in variance and persistence of the North Pacific midlatitude ocean-atmosphere system on decadal timescales, a detailed understanding of how the system works is still lacking. In order to improve our ability to predict the midlatitude Pacific climate variability, a better understanding of how the upper ocean dynamic and thermodynamic processes interact is of fundamental importance.The mid-latitude North Pacific Ocean is subject to both buoyancy and momentum flux forcing at the sea surface. Because of the planetary beta effect, the wind stress-induced upper ocean anomalies tend to propagate westward and accumulate in the Kuroshio Extension region. By transporting warmer tropical-origin water to the mid-latitudes, the Kuroshio Extension is also where the largest air-sea heat exchange and its variability take place. The non-linear nature of the western boundary current circulation variability can further complicate the time-varying upper ocean signals. In this study, Dr Qiu and colleagues examine the processes underlying the observed upper ocean variability based on available in-situ/satellite observations and a high-resolution OGCM hindcast output. The scientific goals of the proposal are (1) to provide a comprehensive description of the decadal variability in the midlatitude North Pacific from the perspective of the upper ocean dynamic and thermodynamic process interaction, (2) to develop testable hypotheses about the role of ocean dynamics in determining the sea surface temperature changes, and (3) to explore whether the long memory of the ocean dynamics can be utilized for improved prediction.The Kuroshio Extension system is an important component of the earth's climate system, particularly in the North Pacific basin. Its influence upon the intensity and tracks of the midlatitude storms and the North Pacific marine ecosystems, as well as its impact on the weather patterns of the U.S. northwest coast, are of important societal relevance. This study aims to gain a better understanding of the roles of ocean dynamics in determining the decadal and longer timescale variability in the North Pacific climate system. This improved understanding could potentially expand our capacity to predict the decadal oceanic state. While the focus of the study is on the KE system specifically, many of the scientific questions, such as the roles of the oceanic adjustment through baroclinic Rossby waves, the intrinsic recirculation gyre variations, the interaction between the western boundary outflow and the bottom topography, and the impact of the upper ocean circulation changes upon the regional SSTs, apply to the other western boundary current systems as well. A better understanding of the KE system variability could serve as a useful step in elucidating the ocean's roles in the midlatitude air-sea coupling in general.