Atmospheric Forcing of Marginal-Sea Overflows

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。其主要动机是需要制定更好的参数化的边际海流出的所有规模，并从观察北欧海溢出显示相当大的年际变化的运输和水温，可能与北大西洋涛动（NAO）。观测到的变化很难单独用标准水力学模型来解释，但可以用结合了大气强迫、水力过程和考虑边缘海环流的联合收割机模型来捕捉。作为第一步，将建立一个新的边缘海外流分析模式，其中包括大气强迫和时间依赖性。该模式将预测下层外流特性的两层交换的强迫和上层流入的温度和盐度。它应适用于从地中海/直布罗陀系统到北欧海的各种尺度的边缘海和海峡，并应上级某些大气环流模式中使用的现有参数化。一个层次的数值模拟使用理想化和现实的水深测量将进行检查大气强迫，如NAO，对溢出的影响，并确定机制负责的时间和幅度观察到的溢出的变化。数值模拟部分将集中在北欧溢出。北欧海上空的大气强迫是北欧海溢出年际变化的主要原因的假设将进行测试。还将研究监测深度溢出的替代方法。最终目标是了解溢出和大西洋经向翻转环流（AMOC）如何响应气候变化。智力优势：这项研究将推进我们对北欧海洋溢出及其对气候强迫的响应的理解，提供一个比几个气候模式中使用的Price-Yang版本更先进的气候响应边缘海边界条件（MSBC），帮助理解模式模拟中的AMOC变率，并帮助提高AMOC对气候变化响应的可预测性。更好地了解深层外流对不断变化的强迫的反应，最终将有助于预测全球变暖、冰川融化和北欧地区其他环境变化的影响。在推广活动方面，研究员普拉特在当地一所学校（科德角学院）为高中生做了演讲。这个项目的主题材料（边缘海，溢出和深海环流）应该是迷人的那个年龄的学生，我们计划回到教室，并谈论它。计划是通过凯茜Cetta，助理校长和教师在CCA协调。研究员普拉特还计划通过开发在线辅助工具，如额外的家庭作业练习和电影，建立他的教科书的教育影响。该项目是对美国CLIVAR（气候变化和可预测性）计划下的大西洋经向翻转环流研究主题的贡献。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The atmospheric forcing of marginal-sea overflows will be investigated. The main motivation is the need to develop better parameterizations of marginal sea outflows of all scales and also from observations of the Nordic Seas overflows showing considerable interannual variability of transport and water temperature, possibly linked to the North Atlantic Oscillation (NAO). The observed variations would be difficult to explain using standard hydraulics models alone, but could be captured in models that combine atmospheric forcing, hydraulic processes and a consideration of the circulation in the marginal sea. As a first step, a new analytic model for a marginal sea outflow that includes atmospheric forcing and time dependence will be developed. The model will predict the lower layer outflow properties of the two-layer exchange given the forcing and the upper layer inflow temperature and salinity. It should be applicable to marginal seas and straits of scales varying from the Med/Gibraltar systems to the Nordic Seas and should be superior to existing parameterizations used in some general circulation models. A hierarchy numerical modeling simulations using both idealized and realistic bathymetry will be conducted to examine the impacts of atmospheric forcing, such as NAO, on the overflow, and to identify mechanisms responsible for the timing and amplitude of observed changes of the overflow. The numerical modeling component will be focused on the Nordic overflows. The hypothesis that the atmospheric forcing over the Nordic Seas is the primary cause for interannual Nordic Seas overflow variability will tested. Alternative ways of monitoring the deep overflows will also be investigated. The ultimate goal is to understand how the overflow and the Atlantic Meridional Overturning Circulation (AMOC) respond to a changing climate.Intellectual Merit:This study will advance our understanding of the Nordic Seas overflow and its responses to climate forcing, provide a climate-responsive marginal-sea boundary condition (MSBC) that is more advanced than the Price-Yang version used in several climate models, help understand AMOC variability in model simulations, and help improve the predictability of AMOC's responses to a changing climate.Broader Impacts:The Nordic Seas region is an important player in the global ocean climate puzzle. A better understanding of the response of the deep outflows to changing forcing will ultimately help predict the global effects of warming, glacier melt, and other environmental changes in the Nordic regions.In terms of outreach activities, investigator Pratt has given presentations to high school students at a local school (Cape Cod Academy). The subject material of this project (marginal seas, overflows, and the abyssal circulation) should be fascinating to students of that age and we plan to go back into the classroom and talk about it. Plans are coordinated through Cathy Cetta, assistant headmaster and teacher at CCA. Investigator Pratt also plans to build on the educational impact of his text book by developing online aids such as additional homework exercises and movies.This project is a contribution to the Atlantic Meridional Overturning Circulation research theme under the U.S. CLIVAR (CLImate VARiability and predictability) Program.