Trace gas measurements during aircraft flights in the tropopause region over Europe and North Africa

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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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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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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Soil gas probes for monitoring trace gas messengers of microbial activity

Scientific Reports ◽

10.1038/s41598-021-86930-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Joseph R. Roscioli ◽

Laura K. Meredith ◽

Joanne H. Shorter ◽

Juliana Gil-Loaiza ◽

Till H. M. Volkmann

Keyword(s):

Microbial Activity ◽

Soil Heterogeneity ◽

Soil Gas ◽

Microbial Processes ◽

Trace Gas ◽

Soil Microbiome ◽

Sampling System ◽

Site Specific ◽

Gas Measurements ◽

Subsurface Monitoring

AbstractSoil microbes vigorously produce and consume gases that reflect active soil biogeochemical processes. Soil gas measurements are therefore a powerful tool to monitor microbial activity. Yet, the majority of soil gases lack non-disruptive subsurface measurement methods at spatiotemporal scales relevant to microbial processes and soil structure. To address this need, we developed a soil gas sampling system that uses novel diffusive soil probes and sample transfer approaches for high-resolution sampling from discrete subsurface regions. Probe sampling requires transferring soil gas samples to above-ground gas analyzers where concentrations and isotopologues are measured. Obtaining representative soil gas samples has historically required balancing disruption to soil gas composition with measurement frequency and analyzer volume demand. These considerations have limited attempts to quantify trace gas spatial concentration gradients and heterogeneity at scales relevant to the soil microbiome. Here, we describe our new flexible diffusive probe sampling system integrated with a modified, reduced volume trace gas analyzer and demonstrate its application for subsurface monitoring of biogeochemical cycling of nitrous oxide (N2O) and its site-specific isotopologues, methane, carbon dioxide, and nitric oxide in controlled soil columns. The sampling system observed reproducible responses of soil gas concentrations to manipulations of soil nutrients and redox state, providing a new window into the microbial response to these key environmental forcings. Using site-specific N2O isotopologues as indicators of microbial processes, we constrain the dynamics of in situ microbial activity. Unlocking trace gas messengers of microbial activity will complement -omics approaches, challenge subsurface models, and improve understanding of soil heterogeneity to disentangle interactive processes in the subsurface biome.

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An evaluation of the performance of chemistry transport models by comparison with research aircraft observations. Part 1: Concepts and overall model performance

Atmospheric Chemistry and Physics ◽

10.5194/acp-3-1609-2003 ◽

2003 ◽

Vol 3 (5) ◽

pp. 1609-1631 ◽

Cited By ~ 35

Author(s):

D. Brunner ◽

J. Staehelin ◽

H. L. Rogers ◽

M. O. Köhler ◽

J. A. Pyle ◽

...

Keyword(s):

Quantitative Methods ◽

Climate Models ◽

Model Performance ◽

Average Concentration ◽

Convective Transport ◽

Trace Gas ◽

Atmospheric Conditions ◽

Time Step ◽

Research Aircraft ◽

Gas Measurements

Abstract. A rigorous evaluation of five global Chemistry-Transport and two Chemistry-Climate Models operated by several different groups in Europe, was performed. Comparisons were made of the models with trace gas observations from a number of research aircraft measurement campaigns during the four-year period 1995-1998. Whenever possible the models were run over the same four-year period and at each simulation time step the instantaneous tracer fields were interpolated to all coinciding observation points. This approach allows for a very close comparison with observations and fully accounts for the specific meteorological conditions during the measurement flights. This is important considering the often limited availability and representativity of such trace gas measurements. A new extensive database including all major research and commercial aircraft measurements between 1995 and 1998, as well as ozone soundings, was established specifically to support this type of direct comparison. Quantitative methods were applied to judge model performance including the calculation of average concentration biases and the visualization of correlations and RMS errors in the form of so-called Taylor diagrams. We present the general concepts applied, the structure and content of the database, and an overall analysis of model skills over four distinct regions. These regions were selected to represent various atmospheric conditions and to cover large geographical domains such that sufficient observations are available for comparison. The comparison of model results with the observations revealed specific problems for each individual model. This study suggests the further improvements needed and serves as a benchmark for re-evaluations of such improvements. In general all models show deficiencies with respect to both mean concentrations and vertical gradients of important trace gases. These include ozone, CO and NOx at the tropopause. Too strong two-way mixing across the tropopause is suggested to be the main reason for differences between simulated and observed CO and ozone values. The generally poor correlations between simulated and measured NOx values suggest that in particular the NOx input by lightning and the convective transport from the polluted boundary layer are still not well described by current parameterizations, which may lead to significant differences in the spatial and seasonal distribution of NOx in the models. Simulated OH concentrations, on the other hand, were found to be in surprisingly good agreement with measured values.

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The high Arctic in extreme winters: vortex, temperature, and MLS and ACE-FTS trace gas evolution

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-505-2008 ◽

2008 ◽

Vol 8 (3) ◽

pp. 505-522 ◽

Cited By ~ 62

Author(s):

G. L. Manney ◽

W. H. Daffer ◽

K. B. Strawbridge ◽

K. A. Walker ◽

C. D. Boone ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Lower Stratosphere ◽

High Arctic ◽

Trace Gas ◽

Satellite Measurements ◽

Broadband Emission ◽

Gas Measurements ◽

Chemistry Experiment ◽

Very High ◽

Good Agreement

Abstract. The first three Arctic winters of the ACE mission represented two extremes of winter variability: Stratospheric sudden warmings (SSWs) in 2004 and 2006 were among the strongest, most prolonged on record; 2005 was a record cold winter. Canadian Arctic Atmospheric Chemistry Experiment (ACE) Validation Campaigns were conducted at Eureka (80° N, 86° W) during each of these winters. New satellite measurements from ACE-Fourier Transform Spectrometer (ACE-FTS), Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), and Aura Microwave Limb Sounder (MLS), along with meteorological analyses and Eureka lidar temperatures, are used to detail the meteorology in these winters, to demonstrate its influence on transport, and to provide a context for interpretation of ACE-FTS and validation campaign observations. During the 2004 and 2006 SSWs, the vortex broke down throughout the stratosphere, reformed quickly in the upper stratosphere, and remained weak in the middle and lower stratosphere. The stratopause reformed at very high altitude, near 75 km. ACE measurements covered both vortex and extra-vortex conditions in each winter, except in late-February through mid-March 2004 and 2006, when the strong, pole-centered vortex that reformed after the SSWs resulted in ACE sampling only inside the vortex in the middle through upper stratosphere. The 2004 and 2006 Eureka campaigns were during the recovery from the SSWs, with the redeveloping vortex over Eureka. 2005 was the coldest winter on record in the lower stratosphere, but with an early final warming in mid-March. The vortex was over Eureka at the start of the 2005 campaign, but moved away as it broke up. Disparate temperature profile structure and vortex evolution resulted in much lower (higher) temperatures in the upper (lower) stratosphere in 2004 and 2006 than in 2005. Satellite temperatures agree well with lidar data up to 50–60 km, and ACE-FTS, MLS and SABER show good agreement in high-latitude temperatures throughout the winters. Consistent with a strong, cold upper stratospheric vortex and enhanced radiative cooling after the SSWs, MLS and ACE-FTS trace gas measurements show strongly enhanced descent in the upper stratospheric vortex in late January through March 2006 compared to that in 2005.

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