Collaborative Research: Reconstructing Carbon-14 of Atmospheric Carbon Monoxide from Law Dome, Antarctica to Constrain Long-Term Hydroxyl Radical Variability

合作研究：重建南极洲 Law Dome 大气一氧化碳的碳 14 以限制长期羟基自由基变化

• 批准号: 1643664
• 负责人: Jeffrey Severinghaus
• 金额: $ 10.29万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1643664&HistoricalAwards=false
• 关键词: Collaborative; Research; Reconstructing; Carbon; 14

Hydroxyl radicals are responsible for removal of most atmospheric trace gases, including pollutants and important greenhouse gases. They have been called the "detergent of the atmosphere". Changes in hydroxyl radical concentration in response to large changes in reactive trace gas emissions, which may happen in the future, are uncertain. This project aims to provide the first estimates of the variability of atmospheric hydroxyl radicals since about 1880 AD when anthropogenic emissions of reactive trace gases were minimal. This will improve understanding of their stability in response to large changes in emissions. The project will also investigate whether ice cores record past changes in Southern Hemisphere westerly winds. These winds are a key component of the global climate system, and have an important influence on ocean circulation and possibly on atmospheric carbon dioxide concentrations. The project team will include three early career scientists, a postdoctoral researcher, and graduate and undergraduate students, working in collaboration with senior scientists and Australian collaborators. Firn air and shallow ice to a depth of about 233 m will be sampled at the Law Dome high-accumulation coastal site in East Antarctica. Trapped air will be extracted from the ice cores on site immediately after drilling. Carbon-14 of carbon monoxide (14CO) will be analyzed in firn and ice-core air samples. Corrections will be made for the in situ cosmogenic 14CO component in the ice, allowing for the atmospheric 14CO history to be reconstructed. This 14CO history will be interpreted with the aid of a chemistry-transport model to place the first observational constraints on the variability of Southern Hemisphere hydroxyl radical concentration after about 1880 AD. An additional component of the project will analyze Krypton-86 in the firn-air and ice-core samples. These measurements will explore whether ice-core Krypton-86 acts as a proxy for barometric pressure variability, and whether this proxy can be used in Antarctic ice cores to infer past movement of the Southern Hemisphere westerly winds.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.

羟基自由基负责去除大多数大气微量气体，包括污染物和重要的温室气体。 它们被称为“大气的清洁剂”。未来可能发生的反应性痕量气体排放大幅变化导致的羟基自由基浓度变化尚不确定。该项目旨在首次估计自公元 1880 年左右以来大气羟基自由基的变化，当时活性微量气体的人为排放量很少。 这将提高人们对其应对排放大幅变化的稳定性的了解。该项目还将调查冰芯是否记录了过去南半球西风的变化。这些风是全球气候系统的关键组成部分，对海洋环流以及可能对大气二氧化碳浓度产生重要影响。 该项目团队将包括三名早期职业科学家、一名博士后研究员以及研究生和本科生，与资深科学家和澳大利亚合作者合作。 将在东南极洲的 Law Dome 高积累沿海地点对深度约 233 m 的冷空气和浅冰进行采样。钻探后，将立即从现场冰芯中提取滞留的空气。将在冰雪和冰芯空气样本中分析一氧化碳 (14CO) 中的碳 14。将对冰中的原位宇宙生成 14CO 成分进行修正，从而重建大气 14CO 历史。 这一 14CO 历史将借助化学输运模型进行解释，以便对公元 1880 年左右后南半球羟基自由基浓度的变化进行首次观测限制。该项目的另一个组成部分将分析空气和冰芯样本中的氪 86。这些测量将探讨冰芯 Krypton-86 是否充当气压变化的代理，以及该代理是否可用于南极冰芯来推断南半球西风过去的运动。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。