Integrated Analyses of the Arctic Freshwater Cycle and its Influence on Global Climate

这项拟议研究的主要目标是探索在地方、泛北极和全球范围内逐步整合北极淡水循环的影响和过程。这项研究将侧重于分析北极水循环中的物理过程，如全球尺度模型所示。这将涉及研究改变北极陆地、大气和海洋环境中淡水收支的过程，将这些过程结合起来，在北极和北大西洋之间进行淡水交换，并最终研究这些过程对温盐环流和全球气候的影响。以下研究问题提供了一个调查框架：（1）土地覆盖的变化，降水量和季节性以及温度如何影响河流向北冰洋的排放？(2)夏季北极锋区的变化将如何影响风暴路径的位置和强度，从而影响北冰洋中部的平均海平面环流？(3)河流径流、降水、温度和大气环流的变化如何影响北极-北大西洋海洋和海冰淡水交换，以及这些量如何影响全球温盐环流？与这些过程相关的反馈的方向和幅度是什么？北冰洋淡水输入和大气环流的变化影响海冰和海洋输送、水团结构、海洋对海冰的热通量和冰团收支。这种相互作用很可能在迫使北极淡水输出发生变化，从而改变北大西洋深水的形成方面发挥重要作用。这些变化有可能通过THC影响全球气候，而THC反过来又会产生或抑制北极系统的进一步变化。科学教育一直是NSF的主要目标。作为我们研究的一个组成部分，我们建议在科罗拉多大学地理系开设一门研讨课程。本课程将侧重于北极气候过程及其在全球系统中的作用，强烈借鉴这里提出的综合分析研究，沿着在以前的NSF/ARCSS研究开发的材料。M. Serreze将与该项目的其他研究人员和一名研究生合作教授这门课程。

The primary goal of this proposed study is to explore the progressive integration of the impacts and processes of the arctic freshwater cycle on the local, pan-Arctic and global scales. This study will focus on analyses of the physical processes, as represented by global scale models, in the arctic water cycle. This will involve the study of processes that modify arctic freshwater budgets in the terrestrial, atmospheric and oceanic environments, the integration of these processes to produce the exchange of freshwater between the Arctic and North Atlantic, and ultimately the influence of these processes on the thermohaline circulation (THC) and global climate. The following research questions provide a framework for investigations: (1) How will changes in land cover, the amount and seasonality of precipitation and temperature influence river discharge to the Arctic Ocean? (2) How will changes in the summer Arctic frontal zone influence the location and intensity of storm tracks and, as a consequence, the mean sea level circulation over the central Arctic Ocean? (3) How do changes in river runoff, precipitation, temperature and the atmospheric circulation influence the Arctic-North Atlantic oceanic and sea ice freshwater exchange, and how do these quantities impact the global thermohaline circulation? What are the directions and magnitudes of feedbacks associated with these processes? Alterations in the freshwater input to, and the atmospheric circulation over, the Arctic Ocean influence the sea ice and ocean transports, water mass structure, the oceanic heat flux to the sea ice, and the ice mass budgets. Such interactions are likely to be important in forcing changes in freshwater exports from the Arctic and, consequently in North Atlantic deep water formation. These changes have the potential to impact global climate through the THC, which in turn can produce or damp further changes in the Arctic system. Science education has always been a principal goal of NSF. As an integral part of our study, we propose to develop a seminar course within the University of Colorado Department of Geography. The course will focus on Arctic climate processes and their role in the global system, drawing strongly from the integrated analyses studies proposed here, along with material developed under prior NSF/ARCSS studies. M. Serreze will teach the course in collaboration with the other investigators on this project and a graduate student.