Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model
International audience Actinic fluxes at large solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have...
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ftinsu:oai:HAL:hal-00295359v1 2023-11-12T04:24:55+01:00 Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model Lamago, D. Dameris, M. Schnadt, C. Eyring, V. Brühl, C. DLR Institut für Physik der Atmosphäre (IPA) Deutsches Zentrum für Luft- und Raumfahrt Oberpfaffenhofen-Wessling (DLR) Max-Planck-Institut für Chemie (MPIC) Max-Planck-Gesellschaft 2003-11-12 https://hal.science/hal-00295359 https://hal.science/hal-00295359/document https://hal.science/hal-00295359/file/acp-3-1981-2003.pdf en eng HAL CCSD European Geosciences Union hal-00295359 https://hal.science/hal-00295359 https://hal.science/hal-00295359/document https://hal.science/hal-00295359/file/acp-3-1981-2003.pdf info:eu-repo/semantics/OpenAccess ISSN: 1680-7316 EISSN: 1680-7324 Atmospheric Chemistry and Physics https://hal.science/hal-00295359 Atmospheric Chemistry and Physics, 2003, 3 (6), pp.1981-1990 [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/article Journal articles 2003 ftinsu 2023-10-25T16:30:17Z International audience Actinic fluxes at large solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs larger than 87.5º on dynamical and chemical processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5º are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially at the end of polar night the conversion of Cl 2 and Cl 2 O 2 into ClO in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93º with those of the sensitivity run with SZAs confined to 87.5º total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is about 4 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to -4 K with obvious consequences for chemical processes. In the Northern Hemisphere the impact of large SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring. This study clearly shows the necessity of considering large SZAs for the calculation of photolysis rates in atmospheric models. Article in Journal/Newspaper polar night Institut national des sciences de l'Univers: HAL-INSU |
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Institut national des sciences de l'Univers: HAL-INSU |
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language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Lamago, D. Dameris, M. Schnadt, C. Eyring, V. Brühl, C. Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
International audience Actinic fluxes at large solar zenith angles (SZAs) are important for atmospheric chemistry, especially under twilight conditions in polar winter and spring. The results of a sensitivity experiment employing the fully coupled 3D chemistry-climate model ECHAM4.L39(DLR)/CHEM have been analysed to quantify the impact of SZAs larger than 87.5º on dynamical and chemical processes in the lower stratosphere, in particular their influence on the ozone layer. Although the actinic fluxes at SZAs larger than 87.5º are small, ozone concentrations are significantly affected because daytime photolytic ozone destruction is switched on earlier, especially at the end of polar night the conversion of Cl 2 and Cl 2 O 2 into ClO in the lower stratosphere. Comparing climatological mean ozone column values of a simulation considering SZAs up to 93º with those of the sensitivity run with SZAs confined to 87.5º total ozone is reduced by about 20% in the polar Southern Hemisphere, i.e., the ozone hole is "deeper'' if twilight conditions are considered in the model because there is about 4 weeks more time for ozone destruction. This causes an additional cooling of the polar lower stratosphere (50 hPa) up to -4 K with obvious consequences for chemical processes. In the Northern Hemisphere the impact of large SZAs cannot be determined on the basis of climatological mean values due to the pronounced dynamic variability of the stratosphere in winter and spring. This study clearly shows the necessity of considering large SZAs for the calculation of photolysis rates in atmospheric models. |
author2 |
DLR Institut für Physik der Atmosphäre (IPA) Deutsches Zentrum für Luft- und Raumfahrt Oberpfaffenhofen-Wessling (DLR) Max-Planck-Institut für Chemie (MPIC) Max-Planck-Gesellschaft |
format |
Article in Journal/Newspaper |
author |
Lamago, D. Dameris, M. Schnadt, C. Eyring, V. Brühl, C. |
author_facet |
Lamago, D. Dameris, M. Schnadt, C. Eyring, V. Brühl, C. |
author_sort |
Lamago, D. |
title |
Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model |
title_short |
Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model |
title_full |
Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model |
title_fullStr |
Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model |
title_full_unstemmed |
Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model |
title_sort |
impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model |
publisher |
HAL CCSD |
publishDate |
2003 |
url |
https://hal.science/hal-00295359 https://hal.science/hal-00295359/document https://hal.science/hal-00295359/file/acp-3-1981-2003.pdf |
genre |
polar night |
genre_facet |
polar night |
op_source |
ISSN: 1680-7316 EISSN: 1680-7324 Atmospheric Chemistry and Physics https://hal.science/hal-00295359 Atmospheric Chemistry and Physics, 2003, 3 (6), pp.1981-1990 |
op_relation |
hal-00295359 https://hal.science/hal-00295359 https://hal.science/hal-00295359/document https://hal.science/hal-00295359/file/acp-3-1981-2003.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782339372270485504 |