The impact of tropical recirculation on polar composition
We derive the tropical modal age of air from an analysis of the water vapor tape recorder. We combine the observationally derived modal age with mean age of air from CO 2 and SF 6 to create diagnostics for the independent evaluation of the vertical transport rate and horizontal recirculation into th...
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ftdoajarticles:oai:doaj.org/article:203d5ba21af4428384b32bd78595b5ce 2023-05-15T13:42:28+02:00 The impact of tropical recirculation on polar composition S. E. Strahan M. R. Schoeberl S. D. Steenrod 2009-04-01T00:00:00Z https://doaj.org/article/203d5ba21af4428384b32bd78595b5ce EN eng Copernicus Publications http://www.atmos-chem-phys.net/9/2471/2009/acp-9-2471-2009.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 1680-7316 1680-7324 https://doaj.org/article/203d5ba21af4428384b32bd78595b5ce Atmospheric Chemistry and Physics, Vol 9, Iss 7, Pp 2471-2480 (2009) Physics QC1-999 Chemistry QD1-999 article 2009 ftdoajarticles 2022-12-31T02:56:38Z We derive the tropical modal age of air from an analysis of the water vapor tape recorder. We combine the observationally derived modal age with mean age of air from CO 2 and SF 6 to create diagnostics for the independent evaluation of the vertical transport rate and horizontal recirculation into the tropics between 16–32 km. These diagnostics are applied to two Global Modeling Initiative (GMI) chemistry and transport model (CTM) age tracer simulations to give new insights into the tropical transport characteristics of the meteorological fields from the GEOS4-GCM and the GEOS4-DAS. Both simulations are found to have modal ages that are in reasonable agreement with the empirically derived age (i.e., transit times) over the entire altitude range. Both simulations show too little horizontal recirculation into the tropics above 22 km, with the GEOS4-DAS fields having greater recirculation. Using CH 4 as a proxy for mean age, comparisons between HALOE and model CH 4 in the Antarctic demonstrate how the strength of tropical recirculation affects polar composition in both CTM experiments. Better tropical recirculation tends to improve the CH 4 simulation in the Antarctic. However, mean age in the Antarctic lower stratosphere can be compromised by poor representation of tropical ascent, tropical recirculation, or vortex barrier strength. The connection between polar and tropical composition shown in this study demonstrates the importance of diagnosing each of these processes separately in order to verify the adequate representation of the processes contributing to polar composition in models. Article in Journal/Newspaper Antarc* Antarctic Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Physics QC1-999 Chemistry QD1-999 |
spellingShingle |
Physics QC1-999 Chemistry QD1-999 S. E. Strahan M. R. Schoeberl S. D. Steenrod The impact of tropical recirculation on polar composition |
topic_facet |
Physics QC1-999 Chemistry QD1-999 |
description |
We derive the tropical modal age of air from an analysis of the water vapor tape recorder. We combine the observationally derived modal age with mean age of air from CO 2 and SF 6 to create diagnostics for the independent evaluation of the vertical transport rate and horizontal recirculation into the tropics between 16–32 km. These diagnostics are applied to two Global Modeling Initiative (GMI) chemistry and transport model (CTM) age tracer simulations to give new insights into the tropical transport characteristics of the meteorological fields from the GEOS4-GCM and the GEOS4-DAS. Both simulations are found to have modal ages that are in reasonable agreement with the empirically derived age (i.e., transit times) over the entire altitude range. Both simulations show too little horizontal recirculation into the tropics above 22 km, with the GEOS4-DAS fields having greater recirculation. Using CH 4 as a proxy for mean age, comparisons between HALOE and model CH 4 in the Antarctic demonstrate how the strength of tropical recirculation affects polar composition in both CTM experiments. Better tropical recirculation tends to improve the CH 4 simulation in the Antarctic. However, mean age in the Antarctic lower stratosphere can be compromised by poor representation of tropical ascent, tropical recirculation, or vortex barrier strength. The connection between polar and tropical composition shown in this study demonstrates the importance of diagnosing each of these processes separately in order to verify the adequate representation of the processes contributing to polar composition in models. |
format |
Article in Journal/Newspaper |
author |
S. E. Strahan M. R. Schoeberl S. D. Steenrod |
author_facet |
S. E. Strahan M. R. Schoeberl S. D. Steenrod |
author_sort |
S. E. Strahan |
title |
The impact of tropical recirculation on polar composition |
title_short |
The impact of tropical recirculation on polar composition |
title_full |
The impact of tropical recirculation on polar composition |
title_fullStr |
The impact of tropical recirculation on polar composition |
title_full_unstemmed |
The impact of tropical recirculation on polar composition |
title_sort |
impact of tropical recirculation on polar composition |
publisher |
Copernicus Publications |
publishDate |
2009 |
url |
https://doaj.org/article/203d5ba21af4428384b32bd78595b5ce |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Atmospheric Chemistry and Physics, Vol 9, Iss 7, Pp 2471-2480 (2009) |
op_relation |
http://www.atmos-chem-phys.net/9/2471/2009/acp-9-2471-2009.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 1680-7316 1680-7324 https://doaj.org/article/203d5ba21af4428384b32bd78595b5ce |
_version_ |
1766168372405338112 |