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

2004 ◽  
Vol 4 (5) ◽  
pp. 1427-1442 ◽  
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.

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

2004 ◽  
Vol 4 (2) ◽  
pp. 1691-1726 ◽  
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.

scholarly journals Quantifying transport into the lowermost stratosphere using simultaneous in-situ measurements of SF<sub>6</sub> and CO<sub>2</sub>

2008 ◽  
Vol 8 (6) ◽  
pp. 21229-21264 ◽  
Author(s):  
H. Bönisch ◽  
A. Engel ◽  
J. Curtius ◽  
T. Birner ◽  
P. Hoor
Keyword(s):  
Mass Balance ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Transit Times ◽  
Residual Transport ◽  
Tropopause Region ◽  
Passive Tracers ◽  
Transport And Mixing ◽  
Extratropical Tropopause

Abstract. The seasonality of transport and mixing of air into the lowermost stratosphere (LMS) is studied using distributions of mean age of air and a~mass balance approach, based on in-situ observations of SF6 and CO2 during the SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) aircraft campaigns. Combining the information of the mean age of air and the water vapour distributions we demonstrate that the tropospheric air transported into the LMS above the extratropical tropopause layer (ExTL) originates predominantly from the tropical tropopause layer (TTL). The concept of our mass balance is based on simultaneous measurements of the two passive tracers and the assumption that transport into the LMS can be described by age spectra which are superposition of two different modes. Based on this concept we conclude that the stratospheric influence on LMS composition is strongest in April with tropospheric fractions (α1) below 20% and that the strongest tropospheric signatures are found in October with (α1 greater than 80%. Beyond the fractions, our mass balance concept allows to calculate the associated transit times for transport of tropospheric air from the tropics into the LMS. The shortest transit times (<0.3 years) are derived for the summer, continuously increasing up to 0.8 years by the end of spring. These findings suggest that strong quasi-horizontal mixing across the weak subtropical jet from summer to mid of autumn and the considerably shorter residual transport time-scales within the lower branch of the Brewer-Dobson circulation in summer than in winter dominates the tropospheric influence in the LMS until the beginning of next year's summer.

scholarly journals Measurements of NO, NO<sub>y</sub>, N<sub>2</sub>O, and O<sub>3</sub> during SPURT: implications for transport and chemistry in the lowermost stratosphere

2005 ◽  
Vol 5 (5) ◽  
pp. 8649-8688 ◽  
Author(s):  
M. I. Hegglin ◽  
D. Brunner ◽  
Th. Peter ◽  
P. Hoor ◽  
H. Fischer ◽  
...  
Keyword(s):  
Atmospheric Transport ◽  
Potential Temperature ◽  
Transport Processes ◽  
Ozone Production ◽  
Data Set ◽  
Latitude Range ◽  
Mixing Ratios ◽  
Tropical Tropopause ◽  
Tropopause Region ◽  
Extratropical Tropopause

Abstract. We present measurements of NO, NOy, O3, and N2O within the lowermost stratosphere (LMS) over Europe obtained during the SPURT project. The measurements cover each of the four seasons during two years between November 2001 and July 2003, and probe the entire altitude and latitude range of the LMS: from 5° N to 85° N equivalent latitude, and from 290 to 375 K potential temperature. The measurements represent a comprehensive data set of these tracers and reveal atmospheric transport processes that influence tracer distributions in the LMS. Mean mixing ratios of stratospheric tracers in equivalent latitude-potential temperature coordinates show a clear seasonal cycle related to the Brewer-Dobson circulation with highest values in spring and lowest values in autumn. Vertical profiles show strong gradients at the extratropical tropopause suggesting that vertical (cross-isentropic) mixing is reduced above the tropopause. Mixing along isentropes is also strongly reduced since pronounced meridional gradients are found on potential temperature surfaces in the LMS. Concurrent large gradients in PV in the vertical and in the meridional direction horizontally suggest the presence of a transport and mixing barrier. Well above the tropopause distinguished seasonal cycles were found in the correlation slopes ΔO3/ΔN2O and ΔNOy/ΔN2O. Smallest slopes found during spring indicate chemically aged stratospheric air originating from high altitudes and latitudes. The slopes are larger in summer and autumn suggesting that a substantial fraction of air takes a 'short-cut' from the tropical tropopause region into the extratropical LMS. The comparison of measured NO with critical NO values at which net ozone production changes from negative to positive implies a net ozone production up to 20 K above the local tropopause in winter, increasing during spring and summer to up to 50 K in autumn. Above this height NO values favor ozone destruction.

scholarly journals Quantifying transport into the lowermost stratosphere using simultaneous in-situ measurements of SF<sub>6</sub> and CO<sub>2</sub>

2009 ◽  
Vol 9 (16) ◽  
pp. 5905-5919 ◽  
Author(s):  
H. Bönisch ◽  
A. Engel ◽  
J. Curtius ◽  
Th. Birner ◽  
P. Hoor
Keyword(s):  
Mass Balance ◽  
Extreme Values ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Transit Times ◽  
Residual Transport ◽  
Tropopause Region ◽  
Passive Tracers ◽  
Extratropical Tropopause

Abstract. The seasonality of transport and mixing of air into the lowermost stratosphere (LMS) is studied using distributions of mean age of air and a mass balance approach, based on in-situ observations of SF6 and CO2 during the SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) aircraft campaigns. Combining the information of the mean age of air and the water vapour distributions we demonstrate that the tropospheric air transported into the LMS above the extratropical tropopause layer (ExTL) originates predominantly from the tropical tropopause layer (TTL). The concept of our mass balance is based on simultaneous measurements of the two passive tracers and the assumption that transport into the LMS can be described by age spectra which are superposition of two different modes. Based on this concept we conclude that the stratospheric influence on LMS composition is strongest in April with extreme values of the tropospheric fractions (α1) below 20% and that the strongest tropospheric signatures are found in October with α1 greater than 80%. Beyond the fractions, our mass balance concept allows us to calculate the associated transit times for transport of tropospheric air from the tropics into the LMS. The shortest transit times (<0.3 years) are derived for the summer, continuously increasing up to 0.8 years by the end of spring. These findings suggest that strong quasi-horizontal mixing across the weak subtropical jet from summer to mid of autumn and the considerably shorter residual transport time-scales within the lower branch of the Brewer-Dobson circulation in summer than in winter dominates the tropospheric influence in the LMS until the beginning of next year's summer.

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

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.

scholarly journals Lapse Rate or Cold Point: The Tropical Tropopause Identified by In Situ Trace Gas Measurements

2018 ◽  
Vol 45 (19) ◽  
pp. 10,756-10,763 ◽  
Author(s):  
Laura L. Pan ◽  
Shawn B. Honomichl ◽  
Thaopaul V. Bui ◽  
Troy Thornberry ◽  
Andrew Rollins ◽  
...  
Keyword(s):  
Lapse Rate ◽  
Trace Gas ◽  
Tropical Tropopause ◽  
Gas Measurements ◽  
Cold Point

Comparison of northern hemispheric and southern hemispheric Mean Age derived from in situ tracer measurements during POLSTRACC and SouthTRAC

2021 ◽  
Author(s):  
Thomas Wagenhäuser ◽  
Markus Jesswein ◽  
Timo Keber ◽  
Tanja Schuck ◽  
Andreas Engel
Keyword(s):  
Southern Hemisphere ◽  
Potential Temperature ◽  
Polar Vortex ◽  
Transport Processes ◽  
Trace Gas ◽  
Model Calculations ◽  
Mixing Ratios ◽  
The Mean ◽  
Gas Measurements

&lt;p&gt;The mean age of air is a powerful diagnostic tool to investigate stratospheric transport processes. It can be derived from suitable trace gas measurements and from model calculations. In contrast to the Northern Hemisphere (NH), data coverage of in situ measurements of such trace gases in the Southern Hemisphere (SH) is sparse. Due to its tropospheric trend and its very long atmospheric lifetime, SF&lt;sub&gt;6 &lt;/sub&gt;is such a suitable trace gas. SF&lt;sub&gt;6&lt;/sub&gt; mixing ratios were measured with an airborne in situ GC-ECD system during several HALO aircraft campaigns, including locations in the SH polar vortex.&lt;/p&gt;&lt;p&gt;Here we present the mean age derived from in situ SF&lt;sub&gt;6&lt;/sub&gt; measurements during the POLSTRACC campaign (Polar Stratosphere in a Changing Climate) in NH winter/spring 2015/2016 and during the SouthTRAC campaign (Transport and Composition of the Southern Hemisphere UTLS) in SH winter/spring 2019. Mean age values over 4 years were observed in both polar vortices. On average, higher mean age values were observed at lower levels of potential temperature during SouthTRAC 2019 than during POLSTRACC 2015/2016. The findings will be discussed in context of the Brewer-Dobson circulation.&lt;/p&gt;

scholarly journals Seasonal cycles and variability of O<sub>3</sub> and H<sub>2</sub>O in the UT/LMS during SPURT

2006 ◽  
Vol 6 (1) ◽  
pp. 109-125 ◽  
Author(s):  
M. Krebsbach ◽  
C. Schiller ◽  
D. Brunner ◽  
G. Günther ◽  
M. I. Hegglin ◽  
...  
Keyword(s):  
Trace Gases ◽  
Distribution Functions ◽  
Trace Gas ◽  
Large Set ◽  
Transport Barrier ◽  
Tropical Tropopause ◽  
Time Period ◽  
Data Coverage ◽  
Insight Into

Abstract. Airborne high resolution in situ measurements of a large set of trace gases including ozone (O3) and total water (H2O) in the upper troposphere and the lowermost stratosphere (UT/LMS) have been performed above Europe within the SPURT project. SPURT provides an extensive data coverage of the UT/LMS in each season within the time period between November 2001 and July 2003. In the LMS a distinct spring maximum and autumn minimum is observed in O3, whereas its annual cycle in the UT is shifted by 2–3 months later towards the end of the year. The more variable H2O measurements reveal a maximum during summer and a minimum during autumn/winter with no phase shift between the two atmospheric compartments. For a comprehensive insight into trace gas composition and variability in the UT/LMS several statistical methods are applied using chemical, thermal and dynamical vertical coordinates. In particular, 2-dimensional probability distribution functions serve as a tool to transform localised aircraft data to a more comprehensive view of the probed atmospheric region. It appears that both trace gases, O3 and H2O, reveal the most compact arrangement and are best correlated in the view of potential vorticity (PV) and distance to the local tropopause, indicating an advanced mixing state on these surfaces. Thus, strong gradients of PV seem to act as a transport barrier both in the vertical and the horizontal direction. The alignment of trace gas isopleths reflects the existence of a year-round extra-tropical tropopause transition layer. The SPURT measurements reveal that this layer is mainly affected by stratospheric air during winter/spring and by tropospheric air during autumn/summer. Normalised mixing entropy values for O3 and H2O in the LMS appear to be maximal during spring and summer, respectively, indicating highest variability of these trace gases during the respective seasons.

scholarly journals Megacity emission plume characteristics in summer and winter investigated by mobile aerosol and trace gas measurements: the Paris metropolitan area

2014 ◽  
Vol 14 (8) ◽  
pp. 11249-11299 ◽  
Author(s):  
S.-L. von der Weiden-Reinmüller ◽  
F. Drewnick ◽  
Q. J. Zhang ◽  
F. Freutel ◽  
M. Beekmann ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Metropolitan Area ◽  
Aromatic Hydrocarbons ◽  
Trace Gas ◽  
Air Masses ◽  
Pollutant Concentrations ◽  
Polycyclic Aromatic ◽  
Gas Measurements ◽  
Background Air ◽  
Transformation Processes

Abstract. For the investigation of megacity emission plume characteristics mobile aerosol and trace gas measurements were carried out in the greater Paris region in July 2009 and January/February 2010 within the EU FP7 MEGAPOLI project. The deployed instruments measured physical and chemical properties of sub-micron aerosol particles, gas phase constituents of relevance for urban air pollution studies and meteorological parameters. The emission plume was identified based on fresh pollutant (e.g. particle-bound polycyclic aromatic hydrocarbons, black carbon, CO2 and NOx) concentration changes in combination with wind direction data. The classification into megacity influenced and background air masses allowed a characterization of the emission plume during summer and winter environmental conditions. On average, a clear increase of fresh pollutant concentrations in plume compared to background air masses was found for both seasons. For example, an average increase of 190% (+8.8 ng m−3) in summer and of 130% (+18.1 ng m−3) in winter was found for particle-bound polycyclic aromatic hydrocarbons in plume air masses. The aerosol particle size distribution in plume air masses was influenced by nucleation and growth due to coagulation and condensation in summer, while in winter only the second process seemed to be initiated by urban pollution. The observed distribution of fresh pollutants in the emission plume – its cross sectional Gaussian-like profile and the exponential decrease of pollutant concentrations with increasing distance to the megacity – are in agreement with model results. Differences between model and measurements were found for plume center location, plume width and axial plume extent. In general, dilution was identified as the dominant process determining the axial variations within the Paris emission plume. For in-depth analysis of transformation processes occurring in the advected plume, simultaneous measurements at a suburban measurement site and a stationary site outside the metropolitan area using the mobile laboratory have proven to be most useful. Organic aerosol oxidation was observed in summer, while in winter transformation processes seemed to occur at a slower rate.

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