Abstract
Abstract. UCATS (the UAS Chromatograph for Atmospheric Trace Species) was designed and built for observations of important atmospheric trace gases from unmanned aircraft systems (UAS) in the upper troposphere and lower stratosphere (UTLS). Initially it measured major chlorofluorocarbons (CFCs) and the stratospheric transport tracers nitrous oxide (N2O) and sulfur hexafluoride (SF6), using gas chromatography with electron capture detection. Compact commercial absorption spectrometers for ozone (O3) and water vapor (H2O) were added to enhance its capabilities on platforms with relatively small payloads. UCATS has since been reconfigured to measure methane (CH4), carbon monoxide (CO), and molecular hydrogen (H2) instead of CFCs and has undergone numerous upgrades to its subsystems. It has served as part of large payloads on stratospheric UAS missions to probe the tropical tropopause region and transport of air into the stratosphere; in piloted aircraft studies of greenhouse gases, transport, and chemistry in the troposphere; and in 2021 is scheduled to return to the study of stratospheric ozone and halogen compounds, one of its original goals. Each deployment brought different challenges, which were largely met or resolved. The design, capabilities, modifications, and some results from UCATS are shown and described here, including changes for future missions.
Highlights
Accurate and precise measurements of trace gases and other atmospheric parameters have resulted in an ever more detailed understanding of the chemistry and physics of Earth’sPublished by Copernicus Publications on behalf of the European Geosciences Union.E
The combination of ozone, water vapor, and longlived trace gases allows for stand-alone experiments with few if any other instruments
It can contribute to missions on large platforms by measuring selected longlived tracers by gas chromatography (GC)/electron capture detectors (ECDs) and by providing backup measurements of species such as ozone and water
Summary
Accurate and precise measurements of trace gases and other atmospheric parameters have resulted in an ever more detailed understanding of the chemistry and physics of Earth’s. The Halocarbons and other Atmospheric Trace Species (HATS) group in what is the Global Monitoring Laboratory (GML) at the National Oceanic and Atmospheric Administration (NOAA) in Boulder, CO, has long been involved in measuring N2O, CFCs, and other trace gases, primarily by using gas chromatography (GC) with electron capture detectors (ECDs) This led to participation in a series of airborne missions to study halogen budgets, ozone loss, and stratospheric transport, starting on the NASA ER2 aircraft in 1991 (Elkins et al, 1996). UCATS completed the Atmospheric Tomography Mission (ATom; 2016–2018), for which the NASA DC-8 aircraft sampled the remote atmosphere over the Atlantic, Pacific, and Southern oceans and parts of the Arctic and Antarctic from near the surface to above 12 km in different seasons Many of these missions required changes to UCATS, and components were upgraded when possible.
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