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  1. AU="Garny, Hella"
  2. AU="Idris, Zamzuri"
  3. AU="Gao, Xinyu"
  4. AU="Tewari, Srishti"
  5. AU="Behrendt, Ulrike" AU="Behrendt, Ulrike"
  6. AU="Margenthaler, Julie A"
  7. AU="Si, Lian-Jing"
  8. AU="Strand, Torbjørn"
  9. AU=Abdoli Amir

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  1. Buch ; Online: Hemispheric asymmetries in recent changes in the stratospheric circulation

    Ploeger, Felix / Garny, Hella

    eISSN: 1680-7324

    2022  

    Abstract: The expected effect of ozone recovery on the stratospheric Brewer–Dobson circulation (BDC) is a slow-down, strongest in the Southern Hemisphere (SH). In contrast, the BDC has been found to weaken more strongly in the Northern Hemisphere (NH) relative to ... ...

    Abstract The expected effect of ozone recovery on the stratospheric Brewer–Dobson circulation (BDC) is a slow-down, strongest in the Southern Hemisphere (SH). In contrast, the BDC has been found to weaken more strongly in the Northern Hemisphere (NH) relative to the SH in recent decades, inducing substantial effects on chemical composition. We investigate hemispheric asymmetries in BDC changes since about 2000 in simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) driven with different reanalyses (ERA5, ERA-Interim, JRA-55, MERRA-2) and contrast those to free-running climate model simulations. We find that age-of-air increases robustly in the NH stratosphere relative to the SH in all reanalyses. Related nitrous oxide changes agree well between reanalysis-driven simulations and satellite measurements, providing observational evidence for the hemispheric asymmetry in BDC changes. We show that the composition changes in reanalyses are caused by structural residual-circulation changes related to an upward shift and strengthening of the deep BDC branch, resulting in longer transit times, and a downward shift and weakening shallow branch in the NH relative to the SH. Although climate model simulations show that ozone recovery will lead to overall reduced circulation and age-of-air trends, the hemispherically asymmetric signal in circulation trends is small compared to internal variability. Therefore, observed circulation trends over the recent past are not in contradiction to expectations from climate models. Furthermore, the hemispheric asymmetry in BDC trends imprints on the composition of the lower stratosphere, and the signal might propagate into the troposphere, potentially affecting composition down to the surface.
    Thema/Rubrik (Code) 551
    Sprache Englisch
    Erscheinungsdatum 2022-04-27
    Erscheinungsland de
    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  2. Buch ; Online: Hemispheric asymmetries in recent changes of the stratospheric circulation

    Ploeger, Felix / Garny, Hella

    eISSN: 1680-7324

    2022  

    Abstract: Despite the expected opposite effects of ozone recovery, the stratospheric Brewer-Dobson circulation (BDC) has been found to weaken in the Northern hemisphere (NH) relative to the Southern hemisphere (SH) in recent decades, inducing substantial effects ... ...

    Abstract Despite the expected opposite effects of ozone recovery, the stratospheric Brewer-Dobson circulation (BDC) has been found to weaken in the Northern hemisphere (NH) relative to the Southern hemisphere (SH) in recent decades, inducing substantial effects on chemical composition. We investigate hemispheric asymmetries in BDC changes since about 2000 in simulations with the transport model CLaMS driven with different reanalyses (ERA5, ERA-Interim, JRA-55, MERRA-2) and contrast those to a suite of free-running climate model simulations. We find that age of air increases robustly in the NH stratosphere relative to the SH in all reanalyses considered. Related nitrous oxide changes agree well between reanalysis-driven simulations and satellite measurements, providing observational evidence for the hemispheric asymmetry in BDC changes. Residual circulation metrics further show that the composition changes are caused by structural BDC changes related to an upward shift and strengthening of the deep BDC branch, resulting in longer transit times, and a downward shift and weakening shallow branch in the NH relative to the SH. All reanalyses agree on this mechanism. Although climate model simulations show that ozone recovery will lead to overall reduced circulation and age of air trends, the hemispherically asymmetric signal in circulation trends is small compared to internal variability. Therefore, the observed circulation trends over the recent past are not in contradiction to expectations from climate models. Furthermore, the hemispheric asymmetry in BDC trends imprints on the composition of the lower stratosphere and the signal might propagate into the troposphere, potentially affecting composition down to the surface.
    Thema/Rubrik (Code) 551
    Sprache Englisch
    Erscheinungsdatum 2022-01-12
    Erscheinungsland de
    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  3. Buch ; Online: Air quality and radiative impacts of downward propagating sudden stratospheric warmings (SSWs)

    Williams, Ryan / Hegglin, Michaela / Jöckel, Patrick / Garny, Hella / Shine, Keith

    eISSN:

    2024  

    Abstract: Sudden stratospheric warmings (SSWs) are abrupt disturbances to the Northern Hemisphere wintertime stratospheric polar vortex that can lead to pronounced regional changes in surface temperature and precipitation. SSWs also strongly impact the ... ...

    Abstract Sudden stratospheric warmings (SSWs) are abrupt disturbances to the Northern Hemisphere wintertime stratospheric polar vortex that can lead to pronounced regional changes in surface temperature and precipitation. SSWs also strongly impact the distribution of chemical constituents within the stratosphere, but the implications of these changes for stratosphere–troposphere exchange (STE) and radiative effects in the upper troposphere–lower stratosphere (UTLS) have not been extensively studied. Here we show, based on a specified-dynamics simulations from the European Centre for Medium-Range Weather Forecasts – Hamburg (ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) chemistry–climate model, that SSWs lead to a pronounced increase in high-latitude ozone just above the tropopause ( > 25 % relative to climatology), persisting for up to 50 d for the ∼50 % of events classified as downward propagating following Hitchcock et al. (2013). This anomalous feature in lowermost-stratospheric ozone is verified from ozone sonde soundings and using the Copernicus Atmospheric Monitoring Service (CAMS) atmospheric composition reanalysis product. A significant dipole anomaly ( > ± 25 %) in water vapour also persists in this region for up to 75 d, with a drying signal above a region of moistening, also evident within the CAMS reanalysis. An enhancement in STE leads to a significant 5 %–10 % increase in near-surface ozone of stratospheric origin over the Arctic, with a typical time lag between 20 and 80 d. The signal also propagates to mid-latitudes, leading to significant enhancements in UTLS ozone and also, with weakened strength, in free tropospheric and near-surface ozone up to 90 d after the event. In quantifying the potential significance for surface air quality breaches above ozone regulatory standards, a risk enhancement of up to a factor of 2 to 3 is calculated following such events. The chemical composition perturbations in the Arctic UTLS result in radiatively driven Arctic ...
    Thema/Rubrik (Code) 333
    Sprache Englisch
    Erscheinungsdatum 2024-01-30
    Erscheinungsland de
    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  4. Buch ; Online: Air quality and radiative impacts of downward-propagating sudden stratospheric warmings (SSWs)

    Williams, Ryan S. / Hegglin, Michaela I. / Jöckel, Patrick / Garny, Hella / Shine, Keith P.

    eISSN: 1680-7324

    2024  

    Abstract: Sudden stratospheric warmings (SSWs) are abrupt disturbances to the Northern Hemisphere wintertime stratospheric polar vortex that can lead to pronounced regional changes in surface temperature and precipitation. SSWs also strongly impact the ... ...

    Abstract Sudden stratospheric warmings (SSWs) are abrupt disturbances to the Northern Hemisphere wintertime stratospheric polar vortex that can lead to pronounced regional changes in surface temperature and precipitation. SSWs also strongly impact the distribution of chemical constituents within the stratosphere, but the implications of these changes for stratosphere–troposphere exchange (STE) and radiative effects in the upper troposphere–lower stratosphere (UTLS) have not been extensively studied. Here we show, based on a specified-dynamics simulations from the European Centre for Medium-Range Weather Forecasts – Hamburg (ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) chemistry–climate model, that SSWs lead to a pronounced increase in high-latitude ozone just above the tropopause ( > 25 % relative to climatology), persisting for up to 50 d for the ∼50 % of events classified as downward propagating following Hitchcock et al. (2013). This anomalous feature in lowermost-stratospheric ozone is verified from ozone sonde soundings and using the Copernicus Atmospheric Monitoring Service (CAMS) atmospheric composition reanalysis product. A significant dipole anomaly ( > ± 25 %) in water vapour also persists in this region for up to 75 d, with a drying signal above a region of moistening, also evident within the CAMS reanalysis. An enhancement in STE leads to a significant 5 %–10 % increase in near-surface ozone of stratospheric origin over the Arctic, with a typical time lag between 20 and 80 d. The signal also propagates to mid-latitudes, leading to significant enhancements in UTLS ozone and also, with weakened strength, in free tropospheric and near-surface ozone up to 90 d after the event. In quantifying the potential significance for surface air quality breaches above ozone regulatory standards, a risk enhancement of up to a factor of 2 to 3 is calculated following such events. The chemical composition perturbations in the Arctic UTLS result in radiatively driven Arctic ...
    Thema/Rubrik (Code) 333
    Sprache Englisch
    Erscheinungsdatum 2024-01-30
    Erscheinungsland de
    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  5. Buch ; Online ; Dissertation / Habilitation: Dynamical coupling of the stratosphere and troposphere in a changing climate

    Walz, Roland [Verfasser] / Garny, Hella [Akademischer Betreuer]

    2022  

    Verfasserangabe Roland Walz ; Betreuer: Hella Garny
    Schlagwörter Geowissenschaften ; Earth Sciences
    Thema/Rubrik (Code) sg550
    Sprache Englisch
    Verlag Universitätsbibliothek der Ludwig-Maximilians-Universität
    Erscheinungsort München
    Dokumenttyp Buch ; Online ; Dissertation / Habilitation
    Datenquelle Digitale Dissertationen im Internet

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  6. Buch ; Audio / Video ; Dissertation / Habilitation: Causes and impacts of changes in the stratospheric meridional circulation in a chemistry-climate model

    Garny, Hella

    (Forschungsbericht / Deutsches Zentrum für Luft- und Raumfahrt ; 2011,3)

    2011  

    Verfasserangabe Hella Garny
    Serientitel Forschungsbericht / Deutsches Zentrum für Luft- und Raumfahrt ; 2011,3
    Sprache Englisch ; Deutsch
    Umfang VII, 139 S., graph. Darst.
    Ausgabenhinweis Als Ms. gedr.
    Verlag DLR
    Erscheinungsort Köln
    Dokumenttyp Buch ; Audio / Video ; Dissertation / Habilitation
    Dissertation / Habilitation Univ., Diss.--München, 2010
    Anmerkung Mit dt. und engl. Zsfassung ; Literaturverz. S. 129 - 138
    Datenquelle Katalog der Technische Informationsbibliothek Hannover

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  7. Buch ; Online ; Dissertation / Habilitation: Modeling of stratospheric transport time distributions for inert and chemically active species

    Fritsch, Frauke [Verfasser] / Garny, Hella [Akademischer Betreuer]

    2020  

    Verfasserangabe Frauke Fritsch ; Betreuer: Hella Garny
    Schlagwörter Geowissenschaften ; Earth Sciences
    Thema/Rubrik (Code) sg550
    Sprache Englisch
    Verlag Universitätsbibliothek der Ludwig-Maximilians-Universität
    Erscheinungsort München
    Dokumenttyp Buch ; Online ; Dissertation / Habilitation
    Datenquelle Digitale Dissertationen im Internet

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  8. Artikel: Effects of missing gravity waves on stratospheric dynamics; part 1: climatology

    Eichinger, Roland / Garny, Hella / Šácha, Petr / Danker, Jessica / Dietmüller, Simone / Oberländer-Hayn, Sophie

    Climate dynamics. 2020 Mar., v. 54, no. 5-6

    2020  

    Abstract: Energy and momentum deposition from planetary-scale Rossby waves as well as from small-scale gravity waves (GWs) largely control stratospheric dynamics. Interactions between these different wave types, however, complicate the quantification of their ... ...

    Abstract Energy and momentum deposition from planetary-scale Rossby waves as well as from small-scale gravity waves (GWs) largely control stratospheric dynamics. Interactions between these different wave types, however, complicate the quantification of their individual contribution to the overall dynamical state of the middle atmosphere. In state-of-the-art general circulation models (GCMs), the majority of the GW spectrum cannot be resolved and therefore has to be parameterised. This is commonly implemented in two discrete schemes, one for GWs that originate from flow over orographic obstacles and one for all other kinds of GWs (non-orographic GWs). In this study, we attempt to gain a deeper understanding of the interactions of resolved with parameterised wave driving and of their influence on the stratospheric zonal winds and on the Brewer–Dobson circulation (BDC). For this, we set up a GCM time slice experiment with two sensitivity simulations: one without orographic GWs and one without non-orographic GWs. Our findings include an acceleration of the polar vortices, which has historically been one of the main reasons for including explicit GW parameterisations in GCMs. Further, we find inter-hemispheric differences in BDC changes when omitting GWs that can be explained by wave compensation and amplification effects. These are partly evoked through local changes in the refractive properties of the atmosphere caused by the omitted GW drag and a thereby increased planetary wave propagation. However, non-local effects on the flow can act to suppress vertical wave fluxes into the stratosphere for a very strong polar vortex. Moreover, we study mean age of stratospheric air to investigate the impact of missing GWs on tracer transport. On the basis of this analysis, we suggest that the larger ratio of planetary waves to GWs leads to enhanced horizontal mixing, which can have a large impact on stratospheric tracer distributions.
    Schlagwörter General Circulation Models ; air ; climate ; climatology ; energy ; gravity waves ; mixing ; momentum ; stratosphere ; wind
    Sprache Englisch
    Erscheinungsverlauf 2020-03
    Umfang p. 3165-3183.
    Erscheinungsort Springer Berlin Heidelberg
    Dokumenttyp Artikel
    ZDB-ID 1471747-5
    ISSN 1432-0894 ; 0930-7575
    ISSN (online) 1432-0894
    ISSN 0930-7575
    DOI 10.1007/s00382-020-05166-w
    Datenquelle NAL Katalog (AGRICOLA)

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  9. Buch ; Online ; Dissertation / Habilitation: Causes and impacts of changes in the stratospheric meridional circulation in a chemistry-climate model

    Garny, Hella

    2010  

    Verfasserangabe vorgelegt von Hella Garny
    Sprache Englisch
    Umfang Online-Ressource
    Dokumenttyp Buch ; Online ; Dissertation / Habilitation
    Dissertation / Habilitation Univ., Diss.--München, 2010
    Datenquelle Katalog der Technische Informationsbibliothek Hannover

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  10. Buch ; Online ; Dissertation / Habilitation: Causes and impacts of changes in the stratospheric meridional circulation in a chemistry-climate model

    Garny, Hella

    2010  

    Verfasserangabe vorgelegt von Hella Garny
    Sprache Englisch
    Umfang Online-Ressource
    Dokumenttyp Buch ; Online ; Dissertation / Habilitation
    Dissertation / Habilitation Univ., Diss.--München, 2010
    Datenquelle Ehemaliges Sondersammelgebiet Küsten- und Hochseefischerei

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