Evolution of water mass transformation and overturning in the western Nordic Seas in a warming climate

北欧海是与大西洋经向翻转环流（AMOC）相关的水团转化的关键区域。在过去的50年里，变暖的大气已经将冬季海冰边缘向西移动了数百公里。北欧海西部边缘沿着海洋的热损失大大增加，格陵兰海和冰岛海内部的热损失减少，这与这种转变是一致的。为了更好地了解水团转化、对流、区域环流、南北热量输送和翻转环流的后果，该项目将采用几种补充工具。这些活动包括理论发展、应用高分辨率海洋/大气/海冰耦合模型的理想配置以及分析该区域最近获得的观测数据集。模型模拟将代表从20世纪世纪中期的大范围冰到今天的减少冰的过渡，然后根据预测的二氧化碳增加情景预测未来。这项工作与气候科学直接相关，也有更广泛的教育影响。该项目将支持博士后两年，并提供物理海洋学，数值方法，应用数学，气候动力学和数据分析方面的培训。还将通过WHOI暑期学生研究员计划（本提案不收取任何费用）向本科生寻求参与。PI还将共同建议并接待一名来自卑尔根大学的博士生。该项目使用理想化的模型，可以控制和单独研究各种强迫机制和海洋动力学的影响，预计这将是重要的。解决海冰退缩对水团变化影响的主要工具是SKRIPS完全耦合海洋/大气/海冰模式，其组成部分包括海洋和冰的MITgcm海冰包和大气的极地天气研究和预报模式。建模研究的动机，并将进行平行，简化的分析模型的对流盆地/边界电流系统与新的考虑冰盖，埃克曼运输，和有限的热容量大气。此外，皮斯帕尔将与合作者维奇在美国。卑尔根分析弹性北方翻转在变暖的气候（罗孚）观测数据集，根据高分辨率建模和理论发展的这个项目。罗孚包括一个跨越边界流的为期两年的系泊阵列，夏季调查，前所未有的冬季调查，滑翔机数据，冬季直接在边界流中部署ARGO浮标，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的学术价值和更广泛的影响评审标准。

The Nordic Seas are a key region for water mass transformation associated with the Atlantic Meridional Overturning Circulation (AMOC). The warming atmosphere has shifted the wintertime sea ice edge westward by hundreds of kilometers over the past fifty years. Greatly enhanced heat loss from the ocean along the western margin of the Nordic Seas and a reduction of heat loss in the interior of the Greenland and Iceland Seas has been coincident with this shift. To improve understanding of the consequences on water mass transformation, convection, the regional circulation, north-south heat transport and overturning circulation, this project will apply several complementary tools. These include theoretical development, the application of an idealized configuration of a high-resolution coupled ocean/atmosphere/sea ice model and the analysis of a recently acquired observational dataset in the region. The model simulations will represent the transition from the large ice extent of the mid 20th century to the reduced ice of present day and then project into the future under predicted increasing CO2 scenarios. The work is directly relevant to climate science and there are also educational broader impacts. The project will support a postdoc for two years and provide training in physical oceanography, numerical methods, applied mathematics, climate dynamics, and data analysis. Participation will also be sought from undergraduate students through the WHOI Summer Student Fellow Program (at no cost to this proposal). The PI will also co-advise and host a PhD student from the Univ. of Bergen for an extended period. The project uses idealized modeling which allows for control and isolated study of the influences of the various forcing mechanisms and ocean dynamics expected to be important. The primary tool to address the influences of sea ice retreat on water mass transformation is the SKRIPS fully coupled ocean/atmosphere/sea ice model, with components including the MITgcm with sea ice package for the ocean and ice and the Polar Weather Research and Forecasting model (WRF) for the atmosphere. The modeling studies are motivated by, and will be carried out in parallel with, simplified analytic models of the convective basin/boundary current system with new consideration of ice cover, Ekman transport, and a finite heat capacity atmosphere. In addition, PI Spall will work with collaborator Vage at the U. Bergen to analyze the Resilient Northern Overturning in a Warming Climate (ROVER) observational dataset, in light of the high resolution modeling and theoretical development of this project. ROVER included a two-year mooring array across the boundary current, summertime surveys, an unprecedented wintertime survey, glider data, wintertime deployment of ARGO floats directly in the boundary current, in addition to routinely collected glider transects across the boundary and a historical climatological data base developed by Vage.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.