Mesoscale fine structure of a tropopause fold over mountains

Woiwode, Wolfgang; Dörnbrack, Andreas; Bramberger, Martina; Friedl-Vallon, Felix; Haenel, Florian; Höpfner, Michael; Johansson, Sören; Kretschmer, Erik; Krisch, Isabell; Latzko, Thomas; Oelhaf, H.; Orphal, J.; Preusse, Peter; Sinnhuber, Björn-Martin; Ungermann, Jörn

doi:10.5194/acp-18-15643-2018

Cited by 20 publications

(26 citation statements)

References 53 publications

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“…At θ = 300-350 K altitude, higher VMRs are visible in the model data compared to the GLORIA observations. The O 3 VMR values simulated by EMAC reproduce the overall measured vertical structure, although finer features in the trace gas distributions are not visible due to the horizontal resolution of EMAC (≈ 125 km) compared to GLORIA (along-track sampling ≈ 3 km, horizontal resolution along viewing direction several 10-100 km; see also Woiwode et al, 2018).…”

Section: Comparison Of Aircraft Measurements To Model Simulationsmentioning

confidence: 72%

“…5a, the polar vortex (estimated by regions that are not marked with a shadow) extended over Central Europe to the Arctic and Siberia. It can be seen from the higher MERRA-2 potential temperature that air masses at the typical flight altitude of 13 km had subsided over southern France and northern Italy (close to waypoint "C"), where a tropopause fold was present along the polar front jet stream on the day of the flight (Woiwode et al, 2018). Towards the end of the flight (after waypoint "D"), high-altitude clouds were observed along the GLORIA line of sight, and no retrievals were possible.…”

Section: Flight On 12 January 2016 (Pgs06)mentioning

confidence: 99%

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Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

Johansson

Santee

Grooß³

et al. 2019

Atmos. Chem. Phys.

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Abstract. The Arctic winter 2015/16 was characterized by cold stratospheric temperatures. Here we present a comprehensive view of the temporal evolution of chlorine in the lowermost stratosphere over the course of the studied winter. We utilize two-dimensional vertical cross sections of ozone (O3) and chlorine nitrate (ClONO2), measured by the airborne limb imager GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) during the POLSTRACC/GW-LCYCLE II/GWEX/SALSA campaigns, to investigate the tropopause region in detail. Observations from three long-distance flights in January, February, and March 2016 are discussed. ClONO2 volume mixing ratios up to 1100 pptv were measured at 380 K potential temperature in mesoscale structures. Similar mesoscale structures are also visible in O3 measurements. Both trace gas measurements are applied to evaluate simulation results from the chemistry transport model CLaMS (Chemical Lagrangian Model of the Stratosphere) and the chemistry–climate model EMAC (ECHAM5/MESSy Atmospheric Chemistry). These comparisons show agreement within the expected performance of these models. Satellite measurements from Aura/MLS (Microwave Limb Sounder) and SCISAT/ACE-FTS (Atmospheric Chemistry Experiment – Fourier Transform Spectrometer) provide an overview over the whole winter and information about the stratospheric situation above the flight altitude. Time series of these satellite measurements reveal unusually low hydrochloric acid (HCl) and ClONO2 at 380 K from the beginning of January to the end of February 2016, while chlorine monoxide (ClO) is strongly enhanced. In March 2016, unusually rapid chlorine deactivation into HCl is observed instead of deactivation into ClONO2, the more typical pathway for deactivation in the Arctic. Chlorine deactivation observed in the satellite time series is well reproduced by CLaMS. Sensitivity simulations with CLaMS demonstrate the influence of low abundances of O3 and reactive nitrogen (NOy) due to ozone depletion and sedimentation of NOy-containing particles, respectively. On the basis of the different altitude and time ranges of these effects, we conclude that the substantial chlorine deactivation into HCl at 380 K arose as a result of very low ozone abundances together with low temperatures. Additionally, CLaMS estimates ozone depletion of at least 0.4 ppmv at 380 K and 1.75 ppmv at 490 K, which is comparable to other extremely cold Arctic winters. We have used CLaMS trajectories to analyze the history of enhanced ClONO2 measured by GLORIA. In February, most of the enhanced ClONO2 is traced back to chlorine deactivation that had occurred within the past few days prior to the GLORIA measurement. In March, after the final warming, air masses in which chlorine has previously been deactivated into ClONO2 have been transported in the remnants of the polar vortex towards the location of measurement for at least 11 d.

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Section: Comparison Of Aircraft Measurements To Model Simulationsmentioning

confidence: 72%

Section: Flight On 12 January 2016 (Pgs06)mentioning

confidence: 99%

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

Johansson

Santee

Grooß³

et al. 2019

Atmos. Chem. Phys.

Self Cite

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show abstract

“…In 2012, the system was extended by an optional O3-DIAL capability (Fix et al, 2019) to be able to measure collocated profiles of O3 and H2O. During the "Polar Stratosphere in a Changing Climate" (POLSTRACC; Oelhaf et al, 2019) campaign in 2016, this capability was used for the first time, however, in a zenith pointing mode for stratospheric observations.…”

Section: Lidar Observations Onboard Halomentioning

confidence: 99%

“…low line-of-sight resolution requires homogeneity in viewing direction as gradients can cause artefacts in the trace gas profiles. Woiwode et al (2019) investigated the applicability of the linear limb-imaging GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) to observe the fine structure of a tropopause fold. Active remote sensing with airborne Differential Absorption Lidar (DIAL) offers both, a high horizontal and vertical resolution directly beneath the aircraft.…”

Section: Introductionmentioning

confidence: 99%

Mixing at the extratropical tropopause as characterized by collocated airborne H₂O and O₃ lidar observations

Schäfler¹,

Fix²,

Wirth³

2020

Preprint

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Abstract. The composition of the extratropical transition layer (ExTL), which is the transition zone between the stratosphere and the troposphere in the mid-latitudes, largely depends on dynamical processes fostering the exchange of air masses. Here we follow the need to better characterize the ExTL in relation to the dynamic situation using the first-ever collocated airborne lidar observations of ozone (O3) and water vapour (H2O) across the tropopause. The potential of such lidar profile data, required for a novel, two-dimensional depiction of the complex trace gas distributions and mixing along cross-sections, is illustrated for a perpendicular jet stream crossing during a research flight over the North Atlantic conducted on 1 October 2017 in the framework of the Wave-driven Isentropic Exchange (WISE) field campaign. The analysis of the ExTL shape and composition uses a combined view of the lidar data in geometrical and tracer-tracer (T-T) space, which was so far not possible from existing observations. For this particular case study, which is considered to be representative for the climatological distribution, the T-T depiction allows to identify distinct mixing regimes that suggest mixing of air masses with differing origin: we find clearly separated mixing of stratospheric air with moist extratropical air as well as with dry tropical air in the surrounding of the extratropical jet stream. This separation is indicative for differing transport pathways in the troposphere which need to be further elaborated using Lagrangian diagnostics. The O3 and H2O distributions confirm strongest mixing above and below the maximum jet stream winds, while it is suppressed in-between. The interrelation of chemical and dynamical discontinuities is investigated and strongest isentropic trace gas gradients are found to be better correlated with maximum isentropic PV gradients than with classical dynamical tropopause definitions. Although the methods neither allow conclusions on the individual mixing process nor on the location and time of the event, the consideration of data subsets allows discussing the formation and interpretation of isentropic and vertical mixing lines in T-T space and to develop hypotheses on mixing at different time-scales. The presented two-dimensional lidar data is considered to be of relevance for the investigation of further synoptic situations leading to mixing across the tropopause and for future validation of chemistry and numerical weather prediction models.

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“…For PGS14 (Fig. 8b,e,h horizontal resolution along viewing direction several 10 -100 km, see also Woiwode et al (2018)).…”

mentioning

confidence: 95%

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: Observations and simulations

Johansson¹,

Santee²,

Grooß³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

The Arctic winter 2015/16 was characterized by cold stratospheric temperatures. Here we present a comprehensive view of the temporal evolution of chlorine in the lowermost stratosphere (LMS) over the course of this winter. We utilize two-dimensional vertical cross sections of ozone (O 3 ) and chlorine nitrate (ClONO 2 ), measured by the airborne limb-imager GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) during the POLSTRACC/ GW-LCYCLE II/ GWEX/ SALSA campaigns, to investigate in detail the tropopause region. Observations from three long-distance flights in Jan-5 uary, February and March 2016 are discussed. ClONO 2 volume mixing ratios up to 1100 pptv were measured at 380 K potential temperature in mesoscale structures. Similar mesoscale structures are also visible in O 3 measurements. Both trace gas measurements are applied to evaluate simulation results from the chemistry transport model CLaMS (Chemical Lagrangian Model of the Stratosphere) and the chemistry climate model EMAC (ECHAM5/MESSy Atmospheric Chemistry). These comparisons show agreement within the expected performance of these models. Satellite measurements from Aura/MLS (Microwave 10 Limb Sounder) and SCISAT/ACE-FTS (Atmospheric Chemistry Experiment -Fourier Transform Spectrometer) provide an overview over the whole winter and information about the stratospheric situation above flight altitude. Time series of these satellite measurements reveal unusually low hydrochloric acid (HCl) and ClONO 2 at 380 K from the beginning of January to the end of February 2016, while chlorine monoxide (ClO) is strongly enhanced. In March 2016, unusually rapid chlorine deactivation into HCl is observed instead of deactivation into ClONO 2 , the more typical pathway for deactivation in the Arctic.15Chlorine deactivation observed in the satellite time series is well reproduced by CLaMS. Sensitivity simulations with CLaMS demonstrate the influence of low abundances of O 3 and reactive nitrogen (NO y ) due to ozone depletion and sedimentation of NO y -containing particles, respectively. On the basis of the different altitude and time ranges of these effects, we conclude that the substantial chlorine deactivation into HCl at 380 K arose as a result of very low ozone abundances together with low temperatures. Additionally, CLaMS estimates ozone depletion of at least 0.4 ppmv at 380 K and 1.75 ppmv at 490 K, which 20 is comparable to other extremely cold Arctic winters. We have used CLaMS trajectories to analyze the history of enhanced 1 Atmos. Chem. Phys. Discuss., https://doi.

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Mesoscale fine structure of a tropopause fold over mountains

Cited by 20 publications

References 53 publications

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

Mixing at the extratropical tropopause as characterized by collocated airborne H₂O and O₃ lidar observations

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: Observations and simulations

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Mesoscale fine structure of a tropopause fold over mountains

Cited by 20 publications

References 53 publications

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

Mixing at the extratropical tropopause as characterized by collocated airborne H2O and O3 lidar observations

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: Observations and simulations

Contact Info

Product

Resources

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Mixing at the extratropical tropopause as characterized by collocated airborne H₂O and O₃ lidar observations