OH and HO 2 chemistry in clean marine air during SOAPEX-2
International audience Model-measurement comparisons of HO x in extremely clean air ([NO]<3 ppt) are reported. Measurements were made during the second Southern Ocean Photochemistry Experiment (SOAPEX-2), held in austral summer 1999 at the Cape Grim Baseline Air Pollution Station in north-western...
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ftinsu:oai:HAL:hal-00300904v1 2023-11-12T04:26:39+01:00 OH and HO 2 chemistry in clean marine air during SOAPEX-2 Sommariva, R. Haggerstone, A.-L. Carpenter, L. J. Carslaw, N. Creasey, D. J. Heard, D. E. Lee, J. D. Lewis, A. C. Pilling, M. J. Zádor, J. Department of Chemistry Environment Department Department of Physical Chemistry 2004-01-20 https://hal.science/hal-00300904 https://hal.science/hal-00300904/document https://hal.science/hal-00300904/file/acpd-4-419-2004.pdf en eng HAL CCSD European Geosciences Union hal-00300904 https://hal.science/hal-00300904 https://hal.science/hal-00300904/document https://hal.science/hal-00300904/file/acpd-4-419-2004.pdf info:eu-repo/semantics/OpenAccess ISSN: 1680-7367 EISSN: 1680-7375 Atmospheric Chemistry and Physics Discussions https://hal.science/hal-00300904 Atmospheric Chemistry and Physics Discussions, 2004, 4 (1), pp.419-470 [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/article Journal articles 2004 ftinsu 2023-10-25T16:27:13Z International audience Model-measurement comparisons of HO x in extremely clean air ([NO]<3 ppt) are reported. Measurements were made during the second Southern Ocean Photochemistry Experiment (SOAPEX-2), held in austral summer 1999 at the Cape Grim Baseline Air Pollution Station in north-western Tasmania, Australia. The free-radical chemistry was studied using a zero-dimensional box-model based upon the Master Chemical Mechanism (MCM). Two versions of the model were used, with different levels of chemical complexity, to explore the role of hydrocarbons upon free-radical budgets under very clean conditions. The "detailed" model was constrained to measurements of CO, CH 4 and 15 NMHCs, while the "simple" model contained only the CO and CH 4 oxidation mechanisms, together with inorganic chemistry. The OH and HO 2 (HO x ) concentrations predicted by the two models agreed to within 5?10%. The model results were compared with the HO x concentrations measured by the FAGE (Fluorescence Assay by Gas Expansion) technique during four days of clean Southern Ocean marine boundary layer (MBL) air. The models overestimated OH concentrations by about 10% on two days and about 20% on the other two days. HO 2 concentrations were measured during two of these days and the models overestimated the measured concentrations by about 40%. Better agreement with measured HO 2 was observed by using data from several MBL aerosol measurements to estimate the aerosol surface area and by increasing the HO 2 uptake coefficient to unity. This reduced the modelled HO 2 overestimate by ~40%, with little effect on OH, because of the poor HO 2 to OH conversion at the low ambient NO x concentrations. Local sensitivity analysis and Morris One-At-A-Time analysis were performed on the "simple" model, and showed the importance of reliable measurements of j(O 1 D) and [HCHO] and of the kinetic parameters that determine the efficiency of O( 1 D) to OH and HCHO to HO 2 conversion. A 2? standard deviation of 30?40% for OH and 25?30% for HO 2 was ... Article in Journal/Newspaper Southern Ocean Institut national des sciences de l'Univers: HAL-INSU Southern Ocean Austral Grim ENVELOPE(-64.486,-64.486,-65.379,-65.379) |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Sommariva, R. Haggerstone, A.-L. Carpenter, L. J. Carslaw, N. Creasey, D. J. Heard, D. E. Lee, J. D. Lewis, A. C. Pilling, M. J. Zádor, J. OH and HO 2 chemistry in clean marine air during SOAPEX-2 |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
International audience Model-measurement comparisons of HO x in extremely clean air ([NO]<3 ppt) are reported. Measurements were made during the second Southern Ocean Photochemistry Experiment (SOAPEX-2), held in austral summer 1999 at the Cape Grim Baseline Air Pollution Station in north-western Tasmania, Australia. The free-radical chemistry was studied using a zero-dimensional box-model based upon the Master Chemical Mechanism (MCM). Two versions of the model were used, with different levels of chemical complexity, to explore the role of hydrocarbons upon free-radical budgets under very clean conditions. The "detailed" model was constrained to measurements of CO, CH 4 and 15 NMHCs, while the "simple" model contained only the CO and CH 4 oxidation mechanisms, together with inorganic chemistry. The OH and HO 2 (HO x ) concentrations predicted by the two models agreed to within 5?10%. The model results were compared with the HO x concentrations measured by the FAGE (Fluorescence Assay by Gas Expansion) technique during four days of clean Southern Ocean marine boundary layer (MBL) air. The models overestimated OH concentrations by about 10% on two days and about 20% on the other two days. HO 2 concentrations were measured during two of these days and the models overestimated the measured concentrations by about 40%. Better agreement with measured HO 2 was observed by using data from several MBL aerosol measurements to estimate the aerosol surface area and by increasing the HO 2 uptake coefficient to unity. This reduced the modelled HO 2 overestimate by ~40%, with little effect on OH, because of the poor HO 2 to OH conversion at the low ambient NO x concentrations. Local sensitivity analysis and Morris One-At-A-Time analysis were performed on the "simple" model, and showed the importance of reliable measurements of j(O 1 D) and [HCHO] and of the kinetic parameters that determine the efficiency of O( 1 D) to OH and HCHO to HO 2 conversion. A 2? standard deviation of 30?40% for OH and 25?30% for HO 2 was ... |
author2 |
Department of Chemistry Environment Department Department of Physical Chemistry |
format |
Article in Journal/Newspaper |
author |
Sommariva, R. Haggerstone, A.-L. Carpenter, L. J. Carslaw, N. Creasey, D. J. Heard, D. E. Lee, J. D. Lewis, A. C. Pilling, M. J. Zádor, J. |
author_facet |
Sommariva, R. Haggerstone, A.-L. Carpenter, L. J. Carslaw, N. Creasey, D. J. Heard, D. E. Lee, J. D. Lewis, A. C. Pilling, M. J. Zádor, J. |
author_sort |
Sommariva, R. |
title |
OH and HO 2 chemistry in clean marine air during SOAPEX-2 |
title_short |
OH and HO 2 chemistry in clean marine air during SOAPEX-2 |
title_full |
OH and HO 2 chemistry in clean marine air during SOAPEX-2 |
title_fullStr |
OH and HO 2 chemistry in clean marine air during SOAPEX-2 |
title_full_unstemmed |
OH and HO 2 chemistry in clean marine air during SOAPEX-2 |
title_sort |
oh and ho 2 chemistry in clean marine air during soapex-2 |
publisher |
HAL CCSD |
publishDate |
2004 |
url |
https://hal.science/hal-00300904 https://hal.science/hal-00300904/document https://hal.science/hal-00300904/file/acpd-4-419-2004.pdf |
long_lat |
ENVELOPE(-64.486,-64.486,-65.379,-65.379) |
geographic |
Southern Ocean Austral Grim |
geographic_facet |
Southern Ocean Austral Grim |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
ISSN: 1680-7367 EISSN: 1680-7375 Atmospheric Chemistry and Physics Discussions https://hal.science/hal-00300904 Atmospheric Chemistry and Physics Discussions, 2004, 4 (1), pp.419-470 |
op_relation |
hal-00300904 https://hal.science/hal-00300904 https://hal.science/hal-00300904/document https://hal.science/hal-00300904/file/acpd-4-419-2004.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782340551865008128 |