On the discrepancy of HCl processing in the core of the wintertime polar vortices
More than 3 decades after the discovery of the ozone hole, the processes involved in its formation are believed to be understood in great detail. Current state-of-the-art models can reproduce the observed chemical composition in the springtime polar stratosphere, especially regarding the quantif...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/18/8647/2018/acp-18-8647-2018.pdf |
| _version_ | 1818038358945824768 |
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| author | J.-U. Grooß R. Müller R. Spang I. Tritscher T. Wegner T. Wegner M. P. Chipperfield W. Feng W. Feng D. E. Kinnison S. Madronich |
| author_facet | J.-U. Grooß R. Müller R. Spang I. Tritscher T. Wegner T. Wegner M. P. Chipperfield W. Feng W. Feng D. E. Kinnison S. Madronich |
| author_sort | J.-U. Grooß |
| collection | DOAJ |
| description | More than 3 decades after the discovery of the ozone hole, the
processes involved in its formation are believed to be understood in
great detail. Current state-of-the-art models can reproduce
the observed chemical composition in the springtime polar stratosphere,
especially regarding the quantification of halogen-catalysed ozone
loss.
However, we report here on a discrepancy between simulations and
observations during the less-well-studied period of the onset of
chlorine activation. During this period, which in the Antarctic is
between May and July, model simulations significantly overestimate
HCl, one of the key chemical species, inside the polar vortex during
polar night. This HCl discrepancy is also observed in the Arctic.
The discrepancy exists in different models to varying extents; here,
we discuss three independent ones, the Chemical Lagrangian
Model of the Stratosphere (CLaMS) as well as the Eulerian
models SD-WACCM (the specified dynamics version of the Whole Atmosphere
Community Climate Model) and TOMCAT/SLIMCAT. The HCl discrepancy points to
some unknown process in the formulation of stratospheric chemistry
that is currently not represented in the models.</p><p>We characterise the HCl discrepancy in space and time for the
Lagrangian chemistry–transport model CLaMS, in which HCl in the
polar vortex core stays about constant from June to August in the
Antarctic, while the observations indicate a continuous HCl decrease
over this period. The somewhat smaller discrepancies in the Eulerian
models SD-WACCM and TOMCAT/SLIMCAT are also presented. Numerical
diffusion in the transport scheme of the Eulerian models is
identified to be a likely cause for the inter-model differences.
Although the missing process has not yet been identified, we
investigate different hypotheses on the basis of the characteristics
of the discrepancy.
An underestimated HCl uptake into the polar stratospheric cloud (PSC) particles that consist
mainly of H<sub>2</sub>O and HNO<sub>3</sub> cannot explain it due to
the temperature correlation of the discrepancy. Also, a direct
photolysis of particulate HNO<sub>3</sub> does not resolve the discrepancy
since it would also cause changes in chlorine chemistry in late
winter which are not observed.
The ionisation caused by galactic cosmic rays provides an additional
NO<sub><i>x</i></sub> and HO<sub><i>x</i></sub> source that can explain only about 20 %
of the discrepancy.
However, the model simulations show that a hypothetical
decomposition of particulate HNO<sub>3</sub> by some other process not
dependent on the solar elevation, e.g. involving galactic cosmic
rays, may be a possible mechanism to resolve the HCl discrepancy.
Since the discrepancy reported here occurs during the beginning of
the chlorine activation period, where the ozone loss rates are small,
there is only a minor impact of about 2 % on the overall ozone
column loss over the course of Antarctic winter and spring. |
| first_indexed | 2024-12-10T07:41:29Z |
| format | Article |
| id | doaj.art-9fd4ed4602df4faa8aca0b9f77d2ec7b |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-10T07:41:29Z |
| publishDate | 2018-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-9fd4ed4602df4faa8aca0b9f77d2ec7b2022-12-22T01:57:18ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242018-06-01188647866610.5194/acp-18-8647-2018On the discrepancy of HCl processing in the core of the wintertime polar vorticesJ.-U. Grooß0R. Müller1R. Spang2I. Tritscher3T. Wegner4T. Wegner5M. P. Chipperfield6W. Feng7W. Feng8D. E. Kinnison9S. Madronich10Institut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich, Jülich, GermanyInstitut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich, Jülich, GermanyInstitut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich, Jülich, GermanyInstitut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich, Jülich, GermanyInstitut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich, Jülich, Germanynow at: KfW Bankengruppe, Frankfurt, GermanySchool of Earth and Environment, University of Leeds, Leeds, UKSchool of Earth and Environment, University of Leeds, Leeds, UKNational Centre for Atmospheric Science, University of Leeds, Leeds, UKAtmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, USAAtmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, USAMore than 3 decades after the discovery of the ozone hole, the processes involved in its formation are believed to be understood in great detail. Current state-of-the-art models can reproduce the observed chemical composition in the springtime polar stratosphere, especially regarding the quantification of halogen-catalysed ozone loss. However, we report here on a discrepancy between simulations and observations during the less-well-studied period of the onset of chlorine activation. During this period, which in the Antarctic is between May and July, model simulations significantly overestimate HCl, one of the key chemical species, inside the polar vortex during polar night. This HCl discrepancy is also observed in the Arctic. The discrepancy exists in different models to varying extents; here, we discuss three independent ones, the Chemical Lagrangian Model of the Stratosphere (CLaMS) as well as the Eulerian models SD-WACCM (the specified dynamics version of the Whole Atmosphere Community Climate Model) and TOMCAT/SLIMCAT. The HCl discrepancy points to some unknown process in the formulation of stratospheric chemistry that is currently not represented in the models.</p><p>We characterise the HCl discrepancy in space and time for the Lagrangian chemistry–transport model CLaMS, in which HCl in the polar vortex core stays about constant from June to August in the Antarctic, while the observations indicate a continuous HCl decrease over this period. The somewhat smaller discrepancies in the Eulerian models SD-WACCM and TOMCAT/SLIMCAT are also presented. Numerical diffusion in the transport scheme of the Eulerian models is identified to be a likely cause for the inter-model differences. Although the missing process has not yet been identified, we investigate different hypotheses on the basis of the characteristics of the discrepancy. An underestimated HCl uptake into the polar stratospheric cloud (PSC) particles that consist mainly of H<sub>2</sub>O and HNO<sub>3</sub> cannot explain it due to the temperature correlation of the discrepancy. Also, a direct photolysis of particulate HNO<sub>3</sub> does not resolve the discrepancy since it would also cause changes in chlorine chemistry in late winter which are not observed. The ionisation caused by galactic cosmic rays provides an additional NO<sub><i>x</i></sub> and HO<sub><i>x</i></sub> source that can explain only about 20 % of the discrepancy. However, the model simulations show that a hypothetical decomposition of particulate HNO<sub>3</sub> by some other process not dependent on the solar elevation, e.g. involving galactic cosmic rays, may be a possible mechanism to resolve the HCl discrepancy. Since the discrepancy reported here occurs during the beginning of the chlorine activation period, where the ozone loss rates are small, there is only a minor impact of about 2 % on the overall ozone column loss over the course of Antarctic winter and spring.https://www.atmos-chem-phys.net/18/8647/2018/acp-18-8647-2018.pdf |
| spellingShingle | J.-U. Grooß R. Müller R. Spang I. Tritscher T. Wegner T. Wegner M. P. Chipperfield W. Feng W. Feng D. E. Kinnison S. Madronich On the discrepancy of HCl processing in the core of the wintertime polar vortices Atmospheric Chemistry and Physics |
| title | On the discrepancy of HCl processing in the core of the wintertime polar vortices |
| title_full | On the discrepancy of HCl processing in the core of the wintertime polar vortices |
| title_fullStr | On the discrepancy of HCl processing in the core of the wintertime polar vortices |
| title_full_unstemmed | On the discrepancy of HCl processing in the core of the wintertime polar vortices |
| title_short | On the discrepancy of HCl processing in the core of the wintertime polar vortices |
| title_sort | on the discrepancy of hcl processing in the core of the wintertime polar vortices |
| url | https://www.atmos-chem-phys.net/18/8647/2018/acp-18-8647-2018.pdf |
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