Deciphering the Antarctic MSA-sea Ice Link with a Combined Regional Forecast and Atmospheric Chemistry Model

利用区域预报和大气化学组合模型破译南极 MSA-海冰联系

• 批准号: 0739127
• 负责人: Cecilia Bitz
• 金额: $ 37.54万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0739127&HistoricalAwards=false
• 关键词: Deciphering; Antarctic; MSA; sea; Ice

AbstractPI: Cecilia M. BitzProposal Number: 0739127 Title: Deciphering the Antarctic MSA-sea ice link with a combined regional forecast and atmospheric chemistry modelIntellectual merit: Sea ice plays multiple important roles in the climate system including reflecting solar radiation, influencing ocean heat uptake, contributing to dense water formation and protection of ice shelves by damping ocean wave action. Reliable records of Antarctic sea ice extent are only available since 1979. In order to further quantitative understanding of the role of Antarctic sea ice in climate, it would be highly desirable to have a longer term record of Antarctic sea ice conditions. Marine phytoplankton produce dimethylsulfide (DMS) which is emitted to the atmosphere where it can be oxidized to methanesulfonic acid (MSA) and sulfur dioxide and eventually deposited in continental ice. Sulfur dioxide can be converted to non seasalt (nss) sulfate or dry deposited to the ice. It has been suggested that MSA and nss sulfate deposited in ice cores can serve as a proxy for sea ice conditions although available evidence shows the relationship can be complicated by several factors including variability in emissions, variability in transport, reactions in transport and variability in deposition. Moreover there remain uncertainties with respect to the relationship between sea-ice and emissions. Whereas it might be presumed that sea ice would limit the growth of phytoplankton and prevent the escape of DMS, some of the highest concentrations of DMS in the marine environment have been measured in melting Antarctic sea ice. The Antarctic Integrated System Science Program ahs funded this project to use an interdisciplinary modeling approach to assess these factors and uncertainties to help determine whether and where sea ice conditions might be reliably extracted from MSA and nss sulfate levels in Antarctic ice cores ice cores. Specifically the MSA-climate relationship will be examined over the period of 1979-2002 using a relatively high resolution regional chemistry model based on the Community Multi-scale Air Quality (CMAQ) modeling system. Meteorological conditions will be input from hind-casts of Polar MM5 (Ohio State polar specific modifications of the fifth-generation Penn State University/National Center for Atmospheric Research Mesoscale Model)/ Large scale chemical boundary conditions will be input from a global chemical transport model, GEOS-Chem (Goddard Earth Observing System-Chemistry). Under collaborative arrangements with high latitude phytoplankton and sea ice algae experts, empirical DMS emissions within the model domain from sea ice will be developed and compared with modeled DMS emissions from an ocean general circulation model that includes sea ice, phytoplankton and sea ice algae. The overall model output will be compared with measurements from atmospheric monitoring sites and depositional records in snow and ice including widely distributed annually resolved records that are being undertaken as part of the International Polar Year (IPY) International Traverses of Antarctica for Science and Education (ITASE). Broader impacts: By investigating the links between MSA and nss sulfate levels in ice cores and sea ice conditions, this project could provide a basis to help advance the understanding of the role of Antarctic sea ice in the global climate system. The project directly combines expertise in global climate modeling, sea ice, and atmospheric chemistry and through collaboration, in marine phytoplankton ecology. A graduate student who is credited with conceiving of this proposal will be supported to conduct his PhD thesis on this interdisciplinary topic. As one element of the marine phytoplankton ecology collaboration, this student is intending to undertake an NSF East Asia Pacific Summer Institute internship in Australia with experts in sea ice algae dimethylsulfonic acid propionate (DMSP, a precursor to DMS) production. Outreach related to the research will be conducted at the annual Polar Science Weekend at the Pacific Science Center in Seattle. Two of the investigators are members of an underrepresented group (female) in climate related science and are early in their academic careers.

摘要PI：Cecilia M. Bitz提案编号：0739127标题：知识价值：海冰在气候系统中起着多种重要作用，包括反射太阳辐射，影响海洋热量吸收，有助于密集水的形成和通过阻尼海浪作用保护冰架。 南极海冰范围的可靠记录是从1979年以来才有的。为了进一步定量地了解南极海冰在气候中的作用，非常需要有一个更长期的南极海冰状况记录。海洋浮游植物产生二甲基硫（DMS），排放到大气中，在大气中氧化成甲磺酸（MSA）和二氧化硫，最终沉积在大陆冰中。 二氧化硫可以转化为非海盐硫酸盐或干沉积到冰中。 有人认为，沉积在冰芯中的MSA和nss硫酸盐可以作为海冰状况的代表，尽管现有证据表明，这种关系可能会因多种因素而复杂化，包括排放的变化、运输的变化、运输的反应和沉积的变化。此外，海冰与排放量之间的关系仍存在不确定性。虽然可以假定海冰会限制浮游植物的生长并阻止二甲基硫醚的逃逸，但在南极海冰融化时测得了海洋环境中二甲基硫醚的一些最高浓度。 南极综合系统科学计划资助了这个项目，使用跨学科的建模方法来评估这些因素和不确定性，以帮助确定是否以及在哪里可以从南极冰芯中的MSA和NSS硫酸盐水平可靠地提取海冰条件。具体而言，MSA气候关系将在1979-2002年期间使用一个相对高分辨率的区域化学模式的基础上，社区多尺度空气质量（CMAQ）模拟系统进行检查。气象条件将从Polar MM 5（第五代宾夕法尼亚州立大学/国家大气研究中心中尺度模型的俄亥俄州州极地特定修改）的后播输入/大尺度化学边界条件将从全球化学传输模型GEOS-Chem（戈达德地球观测系统-化学）输入。根据与高纬度浮游植物和海冰藻类专家的合作安排，将在海冰模型范围内得出经验性二甲硫醚排放量，并与包括海冰、浮游植物和海冰藻类在内的海洋大气环流模型模拟的二甲硫醚排放量进行比较。 模型的总体输出将与大气监测站的测量结果和冰雪沉积记录进行比较，包括作为国际极地年国际科学和教育南极考察的一部分而正在进行的广泛分发的年度解析记录。 更广泛的影响：通过调查冰芯中的MSA和nss硫酸盐水平与海冰状况之间的联系，该项目可以提供基础，帮助促进对南极海冰在全球气候系统中的作用的了解。该项目直接结合了全球气候建模，海冰和大气化学方面的专业知识，并通过合作，在海洋浮游植物生态学。 一个研究生谁是记入构思这一建议将支持进行他的博士论文在这个跨学科的主题。作为海洋浮游植物生态学合作的一个组成部分，这名学生打算在澳大利亚与海冰藻类二甲基磺酸丙酸酯（DMSP，DMS的前体）生产专家一起进行NSF东亚太平洋夏季研究所实习。与这项研究有关的宣传活动将在西雅图太平洋科学中心举行的年度极地科学周末上进行。其中两名研究人员是气候相关科学中代表性不足的群体（女性）的成员，并且处于学术生涯的早期。