Deep ocean mixing and circulation in subpolar seas

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。该项目是对海洋环流和混合的实验研究，特别关注高纬度的深海。首席研究员提议利用华盛顿大学地球物理流体动力学实验室最近开发的几种新技术，研究高纬度海洋的分层旋转环流，特别是针对混合效应、地形效应和密集溢流环流与周围海洋的连通。这项工作将访问一个独特的数据集，从一个相关的NSF资助的领域计划在拉布拉多-格陵兰岛-冰岛-挪威部门的次极地大西洋。在气候模式情景中，预测的全球海洋翻转环流的下降对高纬度环流和混合的参数化物理敏感。密集羽流的下沉发生在复杂的地形山脊、通道和盆地，这些都是非常难以用数值模拟的。例如，随着稠密的水从法罗群岛岸道溢出进入大西洋，最近观察到了强烈的混合、夹带和变异。在100公里的范围内，水团被稀释，它在全球大气环流中的位置也发生了很大的变化。将根据这些观测结果进行以下具体实验：（一）地形复杂盆地中深层密集边界流的路径和不稳定性;（二）深层流的混合和夹带，以及两个推测性实验：（三）极锋的环流和混合;（四）内波与速度和密度锋的相互作用。在这一领域的实验室实验是罕见的，但我们相信有很多原因与真实的流体实验：无论是在嵌入在气候模型中的微观物理（如相变及其对动力学的影响，湍流混合），并在模拟复杂的三维循环的旋转分层流体与复杂的地形。除了气候研究之外，这项关于基本位涡动力学的工作还有助于理解大气环流和其他行星的大气。更广泛的影响：了解海洋气候系统对全球变暖这一更大的问题及其减缓全球海洋环流的预期影响至关重要。该实验室一直是我们领域的学生，研究全球环境的年轻本科生的灵感来源，并通过公开讲座，向公众。华盛顿大学的GFD实验室经常被用作教学工具，并定期为电视制作拍摄科学片段。该项目涉及若干国际合作：（a）与纪念大学的Afanasyev教授，纽芬兰，加拿大，关于应用“光学测高术”和光学厚度技术在拟进行的实验中绘制正压和斜压环流图;（B，GFD l关于下坡流的实验（E. Darelius大学的卑尔根，挪威），密集的羽流在山谷中，如法罗银行渠道，和（c）与GFD实验室实验的博士。挪威特罗姆瑟的Nøst，关于高纬度盆地深环流的路径。该项目是对美国CLIVAR（气候变化和可预测性）计划的大西洋经向翻转环流主题的贡献。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This project is an experimental investigation of oceanic circulation and mixing, particularly focused on the deep ocean at high latitude. Using several new technologies recently developed in the Geophysical Fluid Dynamics (GFD) laboratory at University of Washington the Principal Investigator propose to study the stratified, rotating circulations of the high latitude oceans, particularly aiming at mixing effects, topographic effects and the communication of dense overflow circulations with the surrounding ocean. This work will access a unique data-set from a related NSF-funded field program in the Labrador-Greenland-Iceland-Norway sector of the sub-polar Atlantic Ocean. The predicted decline of the global oceanic overturning circulation, in climate model scenarios, is sensitive to parameterized physics of high-latitude circulation and mixing. The sinking of dense plumes occurs with complex topographic ridges, passages, and basins which are extremely difficult to model numerically. As dense water spills from the Faroe-Bank Channel into the Atlantic for example, intense mixing, entrainment and variability have been recently observed. Over a space of 100 km the water mass is diluted and its place in the global general circulation is greatly altered. Specific experiments, motivated by these observations, will be conducted: (i) pathways and instability of deep, dense boundary currents in topographically complex basins;(ii) mixing and entrainment in deep currents, together with two speculative experiments:(iii) circulation and mixing at the polar front(iv) interaction of internal waves with velocity and density fronts.Intellectual Merit: Research in climate dominantly involves by observations and numerical models. Laboratory experiments in this area are rare, yet we believe there are many reasons for experimenting with real fluids: both in the micro-physics embedded in climate models (like phase change and its effect on dynamics, and turbulent mixing), and in simulation of complex three-dimensional circulations of rotating stratified fluids with complex topography. Beyond climate research, this work on basic potential vorticity dynamics helps in understanding circulations of the atmosphere, and the atmospheres of other planets.Broader impacts: Understanding the ocean climate system is of importance to the larger problem of global warming and its predicted effect in slowing the global ocean circulation. The laboratory has been a source of inspiration for students in our field, for young undergraduates studying the global environment and, through open lectures, to the general public. The University of Washington GFD laboratory is constantly in use as a teaching tool, and is regularly a site of filming science segments for television productions. The project involves several international collaborations: (a) with Professor Afanasyev of Memorial Univ., Newfoundland, Canada on the application of 'optical altimetry' and optical thickness techniques in mapping barotropic and baroclinic circulations in the proposed experiments; (b, with GFD l experiments on downslope flows (Dr. E. Darelius of Univ. Bergen, Norway), dense plumes in valleys like the Faroe Bank Channel, and (c) with GFD laboratory experiments of Dr. O-A. Nøst of Tromsø, Norway, on the pathways of deep circulation in high-latitude basins.This project is contribution to the Atlantic Meridional Overturning Circulation theme of the US CLIVAR (CLImate VARiability and predictability) program.