UAS Chromatograph for Atmospheric Trace Species (UCATS) – a versatile instrument for trace gas measurements on airborne platforms

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.

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UAS Chromatograph for Atmospheric Trace Species (UCATS) – a versatile instrument for trace gas measurements on airborne platforms

10.5194/amt-2020-496 ◽

2021 ◽

Author(s):

Eric J. Hintsa ◽

Fred L. Moore ◽

Dale F. Hurst ◽

Geoff S. Dutton ◽

Bradley D. Hall ◽

...

Keyword(s):

Sulfur Hexafluoride ◽

Stratospheric Ozone ◽

Unmanned Aircraft ◽

Unmanned Aircraft Systems ◽

Trace Gas ◽

Electron Capture Detection ◽

Tropical Tropopause ◽

Trace Species ◽

Tropopause Region ◽

Gas Measurements

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 (UT/LS). 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 ozone (O3) and water vapor (H2O) instruments were added to enhance science missions on platforms with relatively small payloads. Over the past decade, UCATS has 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 will soon return to the study of stratospheric ozone depletion, one of the original goals for UCATS. 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 upcoming missions.

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Seasonality and extent of extratropical TST derived from in-situ CO measurements during SPURT

Atmospheric Chemistry and Physics ◽

10.5194/acp-4-1427-2004 ◽

2004 ◽

Vol 4 (5) ◽

pp. 1427-1442 ◽

Cited By ~ 124

Author(s):

P. Hoor ◽

C. Gurk ◽

D. Brunner ◽

M. I. Hegglin ◽

H. Wernli ◽

...

Keyword(s):

Potential Temperature ◽

Mixing Layer ◽

Trace Gas ◽

Tropical Tropopause ◽

Tropopause Region ◽

Gas Measurements ◽

Transport And Mixing ◽

Extratropical Tropopause ◽

Background Air

Abstract. We present airborne in-situ trace gas measurements which were performed on eight campaigns between November 2001 and July 2003 during the SPURT-project (SPURenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region). The measurements on a quasi regular basis allowed an overview of the seasonal variations of the trace gas distribution in the tropopause region over Europe from 35°-75°N to investigate the influence of transport and mixing across the extratropical tropopause on the lowermost stratosphere. From the correlation of CO and O3 irreversible mixing of tropospheric air into the lowermost stratosphere is identified. The CO distribution indicates that transport and subsequent mixing of tropospheric air across the extratropical tropopause predominantly affects a layer, which closely follows the shape of the local tropopause. In addition, the seasonal cycle of CO2 illustrates the strong coupling of that layer to the extratropical troposphere. Both, horizontal gradients of CO on isentropes as well as the CO-O3-distribution in the lowermost stratosphere reveal that the influence of quasi-horizontal transport and subsequent mixing weakens with distance from the local tropopause. The mixing layer extends to about 25 K in potential temperature above the local tropopause exhibiting only a weak seasonality. However, at large distances from the tropopause a significant influence of tropospheric air is still evident. The relation between N2O and CO2 indicates that a significant contribution of air originating from the tropical tropopause contributes to the background air in the extratropical lowermost stratosphere.

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Aspects of the chemistry of ozone depletion

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1979.0010 ◽

1979 ◽

Vol 290 (1376) ◽

pp. 505-514 ◽

Cited By ~ 4

Keyword(s):

Nitrogen Oxides ◽

Chemical Reactions ◽

Ozone Depletion ◽

Atomic Oxygen ◽

Stratospheric Ozone ◽

Considerable Effect ◽

Laboratory Studies ◽

Trace Species ◽

Halogen Compounds ◽

Anthropogenic Nitrogen

The conversion of stratospheric ozone and atomic oxygen back to molecular oxygen is catalysed by a number of atmospheric trace species such as nitrogen oxides (NO, NO 2 ), halogen (Cl, ClO) and hydrogen (H, HO, HO 2 ) radicals. The concentrations of these species are interrelated by a complex series of chemical reactions where those of hydroperoxy (HO 2 ) are the least well understood. Recent direct laboratory studies of the reactions of HO 2 have a considerable effect on estimates of ozone depletion by anthropogenic nitrogen oxides and halogen compounds.

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Seasonality and extent of extratropical TST derived from in-situ CO measurements during SPURT

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-4-1691-2004 ◽

2004 ◽

Vol 4 (2) ◽

pp. 1691-1726 ◽

Cited By ~ 3

Author(s):

P. Hoor ◽

C. Gurk ◽

D. Brunner ◽

M. I. Hegglin ◽

H. Wernli ◽

...

Keyword(s):

Significant Contribution ◽

Trace Gas ◽

Horizontal Gradients ◽

Tropical Tropopause ◽

Tropopause Region ◽

Gas Measurements ◽

Transport And Mixing ◽

Extratropical Tropopause ◽

Background Air

Abstract. We present airborne in-situ trace gas measurements which were performed on eight campaigns between November 2001 and July 2003 during the SPURT-project (SPURenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region). The measurements on a quasi regular basis allowed an overview on the seasonal variations of the trace gas distribution in the tropopause region over Europe from 35°–75° N to investigate the influence of transport and mixing across the extratropical tropopause on the lowermost stratosphere. From the correlation of CO and O3 irreversible mixing of tropospheric air into the lowermost stratosphere is identified. The CO distribution indicates that transport and subsequent mixing of tropospheric air across the extratropical tropopause predominantely affects a layer, which closely follows the shape of the local tropopause. In addition the seasonal cycle of CO2 illustrates the strong coupling of that layer to the extratropical troposphere. Both, horizontal gradients of CO on isentropes as well as the CO-O3-distribution in the lowermost stratosphere reveal that the influence of quasi-horizontal transport and subsequent mixing weakens with distance from the local tropopause. However, at large distances from the tropopause a significant influence of tropospheric air is still evident. The relation between N2O and CO2 indicates that a significant contribution of air originating from the tropical tropopause contributes to the background air in the extratropical lowermost stratosphere.

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COCAP: a carbon dioxide analyser for small unmanned aircraft systems

Atmospheric Measurement Techniques ◽

10.5194/amt-11-1833-2018 ◽

2018 ◽

Vol 11 (3) ◽

pp. 1833-1849 ◽

Cited By ~ 6

Author(s):

Martin Kunz ◽

Jost V. Lavric ◽

Christoph Gerbig ◽

Pieter Tans ◽

Don Neff ◽

...

Keyword(s):

Carbon Dioxide ◽

Cost Effective ◽

Unmanned Aircraft ◽

Unmanned Aircraft Systems ◽

Temperature Changes ◽

Co2 Sensor ◽

Aircraft Systems ◽

Gas Measurements ◽

Carbon Dioxide Co2 ◽

Atmospheric Trace Gas

Abstract. Unmanned aircraft systems (UASs) could provide a cost-effective way to close gaps in the observation of the carbon cycle, provided that small yet accurate analysers are available. We have developed a COmpact Carbon dioxide analyser for Airborne Platforms (COCAP). The accuracy of COCAP's carbon dioxide (CO2) measurements is ensured by calibration in an environmental chamber, regular calibration in the field and by chemical drying of sampled air. In addition, the package contains a lightweight thermal stabilisation system that reduces the influence of ambient temperature changes on the CO2 sensor by 2 orders of magnitude. During validation of COCAP's CO2 measurements in simulated and real flights we found a measurement error of 1.2 µmol mol−1 or better with no indication of bias. COCAP is a self-contained package that has proven well suited for the operation on board small UASs. Besides carbon dioxide dry air mole fraction it also measures air temperature, humidity and pressure. We describe the measurement system and our calibration strategy in detail to support others in tapping the potential of UASs for atmospheric trace gas measurements.

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