Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model
Atmospheric composition and chemistry above tropical rainforests is currently not well established, particularly for south-east Asia. In order to examine our understanding of chemical processes in this region, the performance of a box model of atmospheric boundary layer chemistry is tested against m...
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ftleicesterunfig:oai:figshare.com:article/10113863 2023-05-15T17:36:40+02:00 Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model T.A.M. Pugh A.R. MacKenzie C.N. Hewitt B. Langford P.M. Edwards K.L. Furneaux D.E. Heard J.R. Hopkins C.E. Jones A. Karunaharan J. Lee G. Mills P. Misztal S. Moller P.S. Monks L.K. Whalley 2010-01-01T00:00:00Z https://figshare.com/articles/journal_contribution/Simulating_atmospheric_composition_over_a_South-East_Asian_tropical_rainforest_performance_of_a_chemistry_box_model/10113863 unknown 2381/18986 https://figshare.com/articles/journal_contribution/Simulating_atmospheric_composition_over_a_South-East_Asian_tropical_rainforest_performance_of_a_chemistry_box_model/10113863 All Rights Reserved Uncategorized Science & Technology Physical Sciences Meteorology & Atmospheric Sciences VOLATILE ORGANIC-COMPOUNDS CONVECTIVE BOUNDARY-LAYER HYDROXY ALKYL NITRATES BIOGENIC NOX EMISSIONS HENRYS LAW CONSTANTS ISOPRENE PHOTOOXIDATION TROPOSPHERIC CHEMISTRY CHEMICAL MECHANISM NITROGEN-OXIDES NORTH-ATLANTIC Text Journal contribution 2010 ftleicesterunfig 2021-11-11T20:05:15Z Atmospheric composition and chemistry above tropical rainforests is currently not well established, particularly for south-east Asia. In order to examine our understanding of chemical processes in this region, the performance of a box model of atmospheric boundary layer chemistry is tested against measurements made at the top of the rainforest canopy near Danum Valley, Malaysian Borneo. Multi-variate optimisation against ambient concentration measurements was used to estimate average canopy-scale emissions for isoprene, total monoterpenes and nitric oxide. The excellent agreement between estimated values and measured fluxes of isoprene and total monoterpenes provides confidence in the overall modelling strategy, and suggests that this method may be applied where measured fluxes are not available, assuming that the local chemistry and mixing are adequately understood. The largest contributors to the optimisation cost function at the point of best-fit are OH (29%), NO (22%) and total peroxy radicals (27%). Several factors affect the modelled VOC chemistry. In particular concentrations of methacrolein (MACR) and methyl-vinyl ketone (MVK) are substantially overestimated, and the hydroxyl radical (OH) concentration is substantially underestimated; as has been seen before in tropical rainforest studies. It is shown that inclusion of dry deposition of MACR and MVK and wet deposition of species with high Henry's Law values substantially improves the fit of these oxidised species, whilst also substantially decreasing the OH sink. Increasing OH production arbitrarily, through a simple OH recycling mechanism , adversely affects the model fit for volatile organic compounds (VOCs). Given the constraints on isoprene flux provided by measurements, a substantial decrease in the rate of reaction of VOCs with OH is the only remaining option to explain the measurement/model discrepancy for OH. A reduction in the isoprene+OH rate constant of 50%, in conjunction with increased deposition of intermediates and some modest OH ... Other Non-Article Part of Journal/Newspaper North Atlantic University of Leicester: Figshare |
institution |
Open Polar |
collection |
University of Leicester: Figshare |
op_collection_id |
ftleicesterunfig |
language |
unknown |
topic |
Uncategorized Science & Technology Physical Sciences Meteorology & Atmospheric Sciences VOLATILE ORGANIC-COMPOUNDS CONVECTIVE BOUNDARY-LAYER HYDROXY ALKYL NITRATES BIOGENIC NOX EMISSIONS HENRYS LAW CONSTANTS ISOPRENE PHOTOOXIDATION TROPOSPHERIC CHEMISTRY CHEMICAL MECHANISM NITROGEN-OXIDES NORTH-ATLANTIC |
spellingShingle |
Uncategorized Science & Technology Physical Sciences Meteorology & Atmospheric Sciences VOLATILE ORGANIC-COMPOUNDS CONVECTIVE BOUNDARY-LAYER HYDROXY ALKYL NITRATES BIOGENIC NOX EMISSIONS HENRYS LAW CONSTANTS ISOPRENE PHOTOOXIDATION TROPOSPHERIC CHEMISTRY CHEMICAL MECHANISM NITROGEN-OXIDES NORTH-ATLANTIC T.A.M. Pugh A.R. MacKenzie C.N. Hewitt B. Langford P.M. Edwards K.L. Furneaux D.E. Heard J.R. Hopkins C.E. Jones A. Karunaharan J. Lee G. Mills P. Misztal S. Moller P.S. Monks L.K. Whalley Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model |
topic_facet |
Uncategorized Science & Technology Physical Sciences Meteorology & Atmospheric Sciences VOLATILE ORGANIC-COMPOUNDS CONVECTIVE BOUNDARY-LAYER HYDROXY ALKYL NITRATES BIOGENIC NOX EMISSIONS HENRYS LAW CONSTANTS ISOPRENE PHOTOOXIDATION TROPOSPHERIC CHEMISTRY CHEMICAL MECHANISM NITROGEN-OXIDES NORTH-ATLANTIC |
description |
Atmospheric composition and chemistry above tropical rainforests is currently not well established, particularly for south-east Asia. In order to examine our understanding of chemical processes in this region, the performance of a box model of atmospheric boundary layer chemistry is tested against measurements made at the top of the rainforest canopy near Danum Valley, Malaysian Borneo. Multi-variate optimisation against ambient concentration measurements was used to estimate average canopy-scale emissions for isoprene, total monoterpenes and nitric oxide. The excellent agreement between estimated values and measured fluxes of isoprene and total monoterpenes provides confidence in the overall modelling strategy, and suggests that this method may be applied where measured fluxes are not available, assuming that the local chemistry and mixing are adequately understood. The largest contributors to the optimisation cost function at the point of best-fit are OH (29%), NO (22%) and total peroxy radicals (27%). Several factors affect the modelled VOC chemistry. In particular concentrations of methacrolein (MACR) and methyl-vinyl ketone (MVK) are substantially overestimated, and the hydroxyl radical (OH) concentration is substantially underestimated; as has been seen before in tropical rainforest studies. It is shown that inclusion of dry deposition of MACR and MVK and wet deposition of species with high Henry's Law values substantially improves the fit of these oxidised species, whilst also substantially decreasing the OH sink. Increasing OH production arbitrarily, through a simple OH recycling mechanism , adversely affects the model fit for volatile organic compounds (VOCs). Given the constraints on isoprene flux provided by measurements, a substantial decrease in the rate of reaction of VOCs with OH is the only remaining option to explain the measurement/model discrepancy for OH. A reduction in the isoprene+OH rate constant of 50%, in conjunction with increased deposition of intermediates and some modest OH ... |
format |
Other Non-Article Part of Journal/Newspaper |
author |
T.A.M. Pugh A.R. MacKenzie C.N. Hewitt B. Langford P.M. Edwards K.L. Furneaux D.E. Heard J.R. Hopkins C.E. Jones A. Karunaharan J. Lee G. Mills P. Misztal S. Moller P.S. Monks L.K. Whalley |
author_facet |
T.A.M. Pugh A.R. MacKenzie C.N. Hewitt B. Langford P.M. Edwards K.L. Furneaux D.E. Heard J.R. Hopkins C.E. Jones A. Karunaharan J. Lee G. Mills P. Misztal S. Moller P.S. Monks L.K. Whalley |
author_sort |
T.A.M. Pugh |
title |
Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model |
title_short |
Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model |
title_full |
Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model |
title_fullStr |
Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model |
title_full_unstemmed |
Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model |
title_sort |
simulating atmospheric composition over a south-east asian tropical rainforest: performance of a chemistry box model |
publishDate |
2010 |
url |
https://figshare.com/articles/journal_contribution/Simulating_atmospheric_composition_over_a_South-East_Asian_tropical_rainforest_performance_of_a_chemistry_box_model/10113863 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
2381/18986 https://figshare.com/articles/journal_contribution/Simulating_atmospheric_composition_over_a_South-East_Asian_tropical_rainforest_performance_of_a_chemistry_box_model/10113863 |
op_rights |
All Rights Reserved |
_version_ |
1766136234732683264 |