The NASA Atmospheric Tomography (ATom) Mission: Imaging the Chemistry of the Global Atmosphere Bulletin of the American Meteorological Society

This article provides an overview of the NASA Atmospheric Tomography (ATom) mission and a summary of selected scientific findings to date. ATom was an airborne measurements and modeling campaign aimed at characterizing the composition and chemistry of the troposphere over the most remote regions of the Pacific, Southern, Atlantic, and Arctic Oceans, and examining the impact of anthropogenic and natural emissions on a global scale. These remote regions dominate global chemical reactivity and are exceptionally important for global air quality and climate. ATom data provide the in situ measurements needed to understand the range of chemical species and their reactions, and to test satellite remote sensing observations and global models over large regions of the remote atmosphere. Lack of data in these regions, particularly over the oceans, has limited our understanding of how atmospheric composition is changing in response to shifting anthropogenic emissions and physical climate change. ATom was designed as a global-scale tomographic sampling mission with extensive geographic and seasonal coverage, tropospheric vertical profiling, and detailed speciation of reactive compounds and pollution tracers. ATom flew the NASA DC-8 research aircraft over four seasons to collect a comprehensive suite of measurements of gases, aerosols, and radical species from the remote troposphere and lower stratosphere on four global circuits from 2016 to 2018. Flights maintained near-continuous vertical profiling of 0.15–13-km altitudes on long meridional transects of the Pacific and Atlantic Ocean basins. Analysis and modeling of ATom data have led to the significant early findings highlighted here.

本文概述了美国国家航空航天局（NASA）大气层析（Atmospheric Tomography, ATom）任务，并总结了截至目前已取得的部分科学研究成果。ATom是一项机载测量与建模研究项目，旨在表征太平洋、南大洋、大西洋及北冰洋最偏远区域上空对流层的大气组成与化学过程，并探究人为与自然排放对全球尺度大气的影响。这些偏远区域主导了全球大气化学反应活性，对全球空气质量与气候具有极为关键的意义。ATom所获取的原位测量数据，有助于学界明确各类化学物质及其反应的分布范围，同时可用于在大片偏远大气区域中验证卫星遥感观测结果与全球大气模型的准确性。此前这些区域（尤其是海洋上空）的数据匮乏，限制了我们对大气组成如何随人为排放变化与自然物理气候变化发生改变的认知。ATom的设计目标为开展全球尺度的层析采样任务，具备广泛的地理与季节覆盖范围，可实现对流层垂直剖面探测，并能对活性化合物与污染示踪物进行精细化的物种形态分析。2016年至2018年间，ATom项目依托NASA DC-8科研飞机，历经四个季节，完成四次全球飞行巡航，在偏远对流层与平流层下部区域采集了涵盖气体、气溶胶与自由基物种的全方位测量数据。飞行任务在太平洋与大西洋海盆的长距离子午向断面上，实现了0.15至13千米高度范围内近乎连续的垂直剖面探测。针对ATom数据的分析与建模研究，已催生了本文所重点介绍的多项早期重要科学发现。