Collaborative research: Deep eastern ocean boundary currents from local submesoscale potential vorticity dynamics to global climate implications

在所有南半球海洋盆地的观测研究中反复出现了大量的深东部边界流的证据。这些向极地流动的核心携带着经向翻转环流的重要组成部分。这些深向极流发生在以赤道表层流和向极潜流为特征的上升流系统下方的一些地区。这些流动影响着南大洋的水团形态，是深海环流的重要组成部分。然而，它们的动态并没有被很好地理解，在气候模型中它们要么表现得很差，要么根本没有表现出来。这项研究将首次尝试了解深东部边界流的动力学及其对气候模拟和预测的影响。该项目包括培训两名研究生，一名博士后研究员，并通过万维网向公众宣传。本项目利用不同观测资料的分析、贝叶斯逆模式和高分辨率区域海洋模式研究深东部边界流。高分辨率海洋模式可以解析可能参与这些深边界流位涡动力学的中尺度和亚中尺度涡动过程。反演模式和高分辨率区域海洋模式的结果将用于建立一个理想化的理论模式和对深东部边界流的理解。拟议的研究还将检查全球耦合模式中深东部边界流的模拟，以及它们对气候模式的不良模拟的后果。大尺度动力学和未来气候预测。虽然在上升流系统中，深东部边界流与上层海洋潜流完全不同，但本研究将受益于对此类潜流的研究，有助于确定相关的动力过程。其中包括：β效应、风旋度、底部坡度、产生和消散罗斯比波的亚中尺度涡旋、涡-地形相互作用、梯度上升涡动量通量、位涡流入条件、位涡输送和亚中尺度涡旋和垂直混合过程的混合、亚中尺度和准地转中尺度涡旋对深层分层的影响、与内部地形有关的纬向海洋流动为东部深部边界流提供补给。

Evidence for substantial deep eastern boundary currents emerges repeatedly from observational studies in all southern hemisphere ocean basins. The core of these poleward flows carries a significant component of the meridional overturning circulation. These deep poleward flows occur in some areas well beneath upwelling systems characterized by an equatorward surface current and a poleward undercurrent. These flows affect the Southern Ocean water mass configuration and are an important part of the deep general circulation. Yet their dynamics are not well understood, and they are either poorly represented or not represented at all in climate models. This study will be the first attempt to understand the dynamics of deep eastern boundary currents and their consequences to climate simulation and projections. The project includes training of two graduate students, one postdoctoral researcher, and outreach to the public via the World Wide Web.This project studies deep eastern boundary currents using an analysis of varied observations, a Bayesian inverse model, and a high resolution regional ocean model. The high resolution ocean model can resolve mesoscale and submesoscale eddy processes that may participate in the potential vorticity dynamics of these deep boundary currents. The results of the inverse model and high resolution regional ocean model will be used to develop an idealized theoretical model and understanding of deep eastern boundary currents. The proposed study will also examine the simulation of deep eastern boundary currents in global coupled models, and the consequences of their poor simulation on the climate models? large scale dynamics and future climate projections. While deep eastern boundary currents are completely distinct from upper-ocean undercurrents in upwelling systems, this study will benefit from work done on such undercurrents, helping identify relevant dynamical processes. These include: beta effect, wind curl, bottom slope, submesoscale eddies generating and dissipating Rossby waves, eddy-topography interactions, up-gradient eddy momentum fluxes, potential vorticity inflow conditions, potential vorticity transport and mixing by submesoscale eddies and by vertical mixing processes, submesoscale and quasi-geostrophic mesoscale eddy effects on the deep stratification, and interior topography-related zonal ocean flows feeding deep eastern boundary currents.