Record of Atmospheric Photochemistry in Firn at South Pole

9903744 Joseph McConnell这项拟议的工作涉及通过测量和解释南极站雪和积雪中的过氧化氢、甲醛和硝酸浓度来发展大约过去两百年来大气氧化能力的历史。 主要目标是建立过去大气光化学的记录，次要目标是评价空间或时间平均化的程度，以解决过去200年来这些物种浓度在统计上的重大变化。 所提出的方法涉及全年采样的空气和近地表雪，夏季采样和分析雪坑和雪芯，并模拟空气-雪化学，以解释观测到的浓度在积雪。 南极站是这项工作的理想选择，因为极端寒冷使化学相对简单，NOAA气候建模和诊断实验室提供了高质量的气象和化学数据，在南方夏季，将在雪桩场周围的两个雪坑中进行密集采样（用于累积观测）。 为了保持对地层和化学层位及标志物的时间控制，靠近桩场是很重要的。 建模方案将在主要研究员在南极和格陵兰中部早期工作期间开发和测试的过氧化氢空气-雪交换物理模型框架的基础上进行扩展。

9903744Joseph McConnellThis proposed work concerns the development of a history of the oxidation capacity of the atmosphere over approximately the past two hundred years by measuring and interpreting the hydrogen peroxide, formaldehyde, and nitric acid concentrations in the snow and firn at South Pole station. The primary goal is to develop a record of past atmospheric photochemistry, with a secondary goal of evaluating the degree of spatial or temporal averaging necessary to resolve statistically significant changes in the concentration of these species over the past 200 years. The proposed approach involves year-round sampling of air and near-surface snow, summer sampling and analysis of snow pits and firn cores, and modeling the air-snow chemistry in order to interpret the observed concentrations in the firn. South Pole station is ideal for this work because the extreme cold makes the chemistry relatively simple, the NOAA Climate Modeling and Diagnostics Laboratory provides a context of high quality meteorological and chemical data, and the year-round occupation of the station makes year-round sampling possible.Intensive sampling during the austral summer will be done in two snow pits around the perimeter of the snow stake field (for accumulation observations). Proximity to the stake field is important in order to maintain time control for stratigraphic and chemical horizons and markers. The modeling program will expand on the framework of physically based models of the air-snow exchange of hydrogen peroxide developed and tested by the principal investigator during earlier work at South Pole and in central Greenland.***