Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model
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 quant...
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ftdoajarticles:oai:doaj.org/article:5f62f7dbf51d4ee9bd4cc825cebe8b06 2023-05-15T18:02:16+02:00 Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model D. Lamago M. Dameris C. Schnadt V. Eyring C. Brühl 2003-01-01T00:00:00Z https://doaj.org/article/5f62f7dbf51d4ee9bd4cc825cebe8b06 EN eng Copernicus Publications http://www.atmos-chem-phys.net/3/1981/2003/acp-3-1981-2003.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 1680-7316 1680-7324 https://doaj.org/article/5f62f7dbf51d4ee9bd4cc825cebe8b06 Atmospheric Chemistry and Physics, Vol 3, Iss 6, Pp 1981-1990 (2003) Physics QC1-999 Chemistry QD1-999 article 2003 ftdoajarticles 2022-12-31T14:11:31Z 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 Directory of Open Access Journals: DOAJ Articles |
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Directory of Open Access Journals: DOAJ Articles |
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language |
English |
topic |
Physics QC1-999 Chemistry QD1-999 |
spellingShingle |
Physics QC1-999 Chemistry QD1-999 D. Lamago M. Dameris C. Schnadt V. Eyring C. Brühl Impact of large solar zenith angles on lower stratospheric dynamical and chemical processes in a coupled chemistry-climate model |
topic_facet |
Physics QC1-999 Chemistry QD1-999 |
description |
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. |
format |
Article in Journal/Newspaper |
author |
D. Lamago M. Dameris C. Schnadt V. Eyring C. Brühl |
author_facet |
D. Lamago M. Dameris C. Schnadt V. Eyring C. Brühl |
author_sort |
D. Lamago |
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 |
Copernicus Publications |
publishDate |
2003 |
url |
https://doaj.org/article/5f62f7dbf51d4ee9bd4cc825cebe8b06 |
genre |
polar night |
genre_facet |
polar night |
op_source |
Atmospheric Chemistry and Physics, Vol 3, Iss 6, Pp 1981-1990 (2003) |
op_relation |
http://www.atmos-chem-phys.net/3/1981/2003/acp-3-1981-2003.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 1680-7316 1680-7324 https://doaj.org/article/5f62f7dbf51d4ee9bd4cc825cebe8b06 |
_version_ |
1766172075569971200 |