Collaborative Research: Understanding the role of Arctic cyclones - A system approach

合作研究：了解北极气旋的作用 - 系统方法

• 批准号: 1602720
• 负责人: John Walsh
• 金额: $ 18.69万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-15 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1602720&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; role; Arctic

Arctic cyclones are an important contributor to sea ice deformation and oceanic mixing. Changes
in storm activity, and associated atmospheric feedbacks, have been linked to increased seasonality of the high north in the last decade, and with sea ice depletion during summer months. Cyclones are also likely to respond to changes in Arctic ice cover and ocean state indicating that
the atmosphere-ocean-ice system is tightly coupled through processes related to cyclones. Previous Arctic modeling studies typically used regional model simulations without full coupling
of the atmosphere-ocean-ice system, or fully coupled global climate models that do not permit year-on-year comparison with the observational record. This study will avoid such limitations by using
the Regional Arctic System Model (RASM), for which output corresponds directly with month-on-month observational records. This
will allow assessment of the ice-ocean-atmosphere coupling processes on multiple temporal
and spatial scales, and to relate them to limited Arctic Ocean measurements to build a more complete understanding of how increased cyclone activity may be helping to shift the surface climate of the Arctic to a new, warmer state with seasonal sea ice cover, and of how cyclones
will respond to this new Arctic Ocean state. The impact of cyclones on Arctic stakeholder sectors in northern and western Alaska, including coastal communities and marine transport, will be assessed through a partnership with the Alaska Center for Climate Assessment and Policy and the project's inventory of Arctic cyclones and associated ocean and sea ice conditions will be archived at the National Snow and Ice Data Center. Historical time series of annual and seasonal Arctic cyclone activity, maps of tracks and intensities of Arctic cyclones, and case studies of intense or impactful cyclones will be made available on a project web page. The project will engage graduate students and a post-doctoral fellow,
and results will be used in atmospheric and oceanic science undergraduate and graduate level courses at the project institutions. Outcomes from this work will be address priorities in the US National Strategy for the Arctic Region and will address key uncertainties in understanding extreme events and their role in the Arctic climate system. The recent loss of Arctic sea ice has increased the potential for ocean-atmosphere coupling
in the Arctic, especially in areas of low ice concentration or where the ice edge has receded. An important aspect of increased ocean-atmosphere Arctic coupling is the
 potential increase
of the ocean's response to storms. Where once mitigated by thick ice, wind-induced ice deformation and oceanic mixing are increasing as the ice pack thins. The decreasing Arctic ice cover and associated warming of the Arctic Ocean may also impact cyclone intensity and frequency. This grant will support investigation of changes in atmosphere-ice-ocean coupling in the presence of cyclones in the Arctic. It will advance our understanding of coupled atmosphere-ocean-ice processes with a focus on the role and response of cyclones in altering the state of the Arctic system. A cyclone tracking scheme will be applied to reanalyses, yielding an inventory of Arctic cyclone locations, tracks, and intensities that will provide a framework for analysis of ice and upper-ocean responses to storms. The responses of ice concentration, ocean temperature and salinity, and associated ice mass balance before, during, and after cyclones at a variety of intensities will be documented. The same analysis will be applied
to output from the high-resolution Regional Arctic System Model (RASM) and to output from
a suite of global climate models (GCMs). Using a novel set of metrics computed from the output of RASM, peak temporal and spatial scales of oceanic mixing, sea ice deformation, and turbulent fluxes associated with the passage of storms in the Arctic will be determined, in order to assess coupled cyclone-ocean-sea ice processes. Changes in the cyclone climatology between pairs of coupled RASM simulations, that differ only in sea ice and ocean state, and in current and end of the 21st century CMIP5 simulations will allow for assessment of cyclone response to changing ocean and ice state. This award is made by the Arctic Section of NSF Polar Programs and co-funded by the NSF GEO effort PREEVENTS.

北极气旋是造成海冰变形和海洋混合的重要因素。风暴活动的变化和相关的大气反馈，与过去十年北方高地的季节性增加以及夏季月份的海冰枯竭有关。气旋也可能对北极冰盖和海洋状况的变化做出反应，这表明大气-海洋-冰系统通过与气旋相关的过程紧密耦合。以前的北极建模研究通常使用区域模型模拟，而不是大气-海洋-冰层系统的完全耦合，或者完全耦合的全球气候模型，不允许与观测记录进行同比比较。这项研究将通过使用北极区域系统模型(RASM)来避免这种限制，该模型的输出直接与月度观测记录相对应。这将能够在多个时间和空间尺度上评估冰-海洋-大气耦合过程，并将它们与有限的北冰洋测量联系起来，以更全面地了解气旋活动增加如何有助于将北极地表气候转变为具有季节性海冰覆盖的新的、更温暖的状态，以及气旋将如何应对这种新的北冰洋状态。将通过与阿拉斯加气候评估和政策中心的合作，评估气旋对阿拉斯加北部和西部的北极利益攸关方部门，包括沿海社区和海洋运输的影响，该项目的北极气旋及相关海洋和海冰状况清单将保存在国家冰雪数据中心。北极气旋年度和季节活动的历史时间序列、北极气旋的轨迹和强度地图以及强烈或有影响的气旋的案例研究将在项目网页上提供。该项目将招收研究生和一名博士后研究员，其成果将用于项目机构的大气和海洋科学本科生和研究生课程。这项工作的成果将是美国北极地区国家战略的优先事项，并将解决在理解极端事件及其在北极气候系统中的作用方面的关键不确定性。最近北极海冰的消失增加了北极海气耦合的可能性，特别是在冰层密度较低或冰缘已经消退的地区。北极海洋-大气耦合增强的一个重要方面是海洋对风暴的反应可能增加。曾经被厚冰缓解的地方，随着冰层变薄，风引起的冰变形和海洋混合正在增加。北极冰盖的减少和北冰洋的相关变暖也可能影响气旋的强度和频率。这笔赠款将支持对北极气旋存在时大气-冰-海洋耦合变化的调查。它将促进我们对大气-海洋-冰耦合过程的理解，重点是气旋在改变北极系统状态方面的作用和反应。气旋跟踪计划将应用于再分析，产生北极气旋位置、路径和强度的清单，这将为分析冰和上层海洋对风暴的反应提供一个框架。将记录不同强度的气旋之前、期间和之后的冰浓度、海洋温度和盐度以及相关的冰质量平衡的反应。同样的分析将应用于高分辨率北极区域系统模型(RASM)和一套全球气候模型(GCM)的输出。利用RASM输出计算的一套新的度量标准，将确定与北极风暴过境有关的海洋混合、海冰变形和湍流通量的时间和空间峰值尺度，以评估气旋-海洋-海冰耦合过程。在成对的RASM模拟之间的气旋气候学的变化，仅在海冰和海洋状态不同，以及在当前和21世纪末的CMIP5模拟中，将允许评估气旋对海洋和冰状态变化的响应。该奖项由NSF极地计划的北极部分颁发，并由NSF GEO Effort PREEVENTS共同资助。