The NASA Atmospheric Tomography (ATom) Mission: Imaging the Chemistry of the Global Atmosphere

Abstract

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.

Nitrogen oxides in the free troposphere: Implications for tropospheric oxidants and the interpretation of satellite NO2 measurements

“…The source of these VOCs is likely oceanic (Thames et al, 2020) and would depress model OH, which could then be compensated by an increase in the OH source from pNO3photolysis. The OH increase implied by pNO3recycling decreases the global atmospheric methane lifetime from 8.0 years to 7.0 years, worsening the agreement with the value of 9.1 ± 0.9 years inferred from the methylchloroform proxy (Prather et al, 2012), but again this could be compensated by a model underestimate of OH reactivity (Travis et al, 2020;Kim et al, 2022).…”

“…We use observations from the SEAC 4 RS (August-September 2013; Toon et al, 2016) and DC3 (April-May 2012; Barth et al, 2015) campaigns over the southeastern US (25º-40ºN; 65º-100ºW), and the ATom campaign (4 seasonal deployments in 2016-18) over the Pacific and Atlantic oceans (Thompson et al, 2022). For all three campaigns, we use measurements from the NASA DC-8 aircraft, which has a ~12 km ceiling.…”

Inferring the vertical distribution of CO and CO2 from TCCON total column values using the TARDISS algorithm

“…The Atmospheric Tomography Mission (ATom) generated a global dataset to study the interactions of anthropogenic air pollution and greenhouse gases from Summer 2016 through Spring 2018 (Wofsy et al, 2021;Thompson et al, 2022). During this mission, the NASA DC-8 aircraft made measurements of trace gases worldwide.…”

Hydrocarbon Tracers Suggest Methane Emissions from Fossil Sources Occur Predominately Before Gas Processing and That Petroleum Plays Are a Significant Source

“…In this study, we employ global observations from aircraft, including the 2009–2011 High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) 6 and the 2016–2018 Atmospheric Tomography (ATom) 7 missions, which provide vertical profiles of a variety of constituents, including C 2 H 6 and C 3 H 8 , around the remote atmospheres of the globe. Together with the large-scale chemical transport model GEOS-Chem, we estimate global fossil emissions of C 2 H 6 and C 3 H 8 .…”

“…In this study, we employ global observations from aircraft, including the 2009−2011 High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) 6 and the 2016−2018 Atmospheric Tomography (ATom) 7…”