Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela – sources, impacts and interannual variability
First long-term observations of South American biomass burning aerosol within the tropical lower free troposphere are presented. The observations were conducted between 2007 and 2009 at a high altitude station (4765 m a.s.l.) on the Pico Espejo, Venezuela. Sub-micron particle volume, number conc...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2013-10-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/13/9837/2013/acp-13-9837-2013.pdf |
| _version_ | 1818354001576460288 |
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| author | T. Hamburger M. Matisāns P. Tunved J. Ström S. Calderon P. Hoffmann G. Hochschild J. Gross T. Schmeissner A. Wiedensohler R. Krejci |
| author_facet | T. Hamburger M. Matisāns P. Tunved J. Ström S. Calderon P. Hoffmann G. Hochschild J. Gross T. Schmeissner A. Wiedensohler R. Krejci |
| author_sort | T. Hamburger |
| collection | DOAJ |
| description | First long-term observations of South American biomass burning aerosol within the tropical lower free troposphere are presented. The observations were conducted between 2007 and 2009 at a high altitude station (4765 m a.s.l.) on the Pico Espejo, Venezuela. Sub-micron particle volume, number concentrations of primary particles and particle absorption were observed. Orographic lifting and shallow convection leads to a distinct diurnal cycle at the station. It enables measurements within the lower free troposphere during night-time and observations of boundary layer air masses during daytime and at their transitional regions. The seasonal cycle is defined by a wet rainy season and a dry biomass burning season. The particle load of biomass burning aerosol is dominated by fires in the Venezuelan savannah. Increases of aerosol concentrations could not be linked to long-range transport of biomass burning plumes from the Amazon basin or Africa due to effective wet scavenging of particles. Highest particle concentrations were observed within boundary layer air masses during the dry season. Ambient sub-micron particle volume reached 1.4±1.3 μm<sup>3</sup> cm<sup>−3</sup>, refractory particle number concentrations (at 300 °C) 510±420 cm<sup>−3</sup> and the absorption coefficient 0.91±1.2 Mm<sup>−1</sup>. The respective concentrations were lowest within the lower free troposphere during the wet season and averaged at 0.19±0.25 μm<sup>3</sup> cm<sup>−3</sup>, 150±94 cm<sup>−3</sup> and 0.15±0.26 Mm<sup>−1</sup>. A decrease of particle concentrations during the dry seasons from 2007–2009 could be connected to a decrease in fire activity in the wider region of Venezuela using MODIS satellite observations. The variability of biomass burning is most likely linked to the El Niño–Southern Oscillation (ENSO). Low biomass burning activity in the Venezuelan savannah was observed to follow La Niña conditions, high biomass burning activity followed El Niño conditions. |
| first_indexed | 2024-12-13T19:18:29Z |
| format | Article |
| id | doaj.art-d473a7ed09584c4cb1e636ca35eb34e7 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-13T19:18:29Z |
| publishDate | 2013-10-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-d473a7ed09584c4cb1e636ca35eb34e72022-12-21T23:34:13ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242013-10-0113199837985310.5194/acp-13-9837-2013Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela – sources, impacts and interannual variabilityT. HamburgerM. MatisānsP. TunvedJ. StrömS. CalderonP. HoffmannG. HochschildJ. GrossT. SchmeissnerA. WiedensohlerR. KrejciFirst long-term observations of South American biomass burning aerosol within the tropical lower free troposphere are presented. The observations were conducted between 2007 and 2009 at a high altitude station (4765 m a.s.l.) on the Pico Espejo, Venezuela. Sub-micron particle volume, number concentrations of primary particles and particle absorption were observed. Orographic lifting and shallow convection leads to a distinct diurnal cycle at the station. It enables measurements within the lower free troposphere during night-time and observations of boundary layer air masses during daytime and at their transitional regions. The seasonal cycle is defined by a wet rainy season and a dry biomass burning season. The particle load of biomass burning aerosol is dominated by fires in the Venezuelan savannah. Increases of aerosol concentrations could not be linked to long-range transport of biomass burning plumes from the Amazon basin or Africa due to effective wet scavenging of particles. Highest particle concentrations were observed within boundary layer air masses during the dry season. Ambient sub-micron particle volume reached 1.4±1.3 μm<sup>3</sup> cm<sup>−3</sup>, refractory particle number concentrations (at 300 °C) 510±420 cm<sup>−3</sup> and the absorption coefficient 0.91±1.2 Mm<sup>−1</sup>. The respective concentrations were lowest within the lower free troposphere during the wet season and averaged at 0.19±0.25 μm<sup>3</sup> cm<sup>−3</sup>, 150±94 cm<sup>−3</sup> and 0.15±0.26 Mm<sup>−1</sup>. A decrease of particle concentrations during the dry seasons from 2007–2009 could be connected to a decrease in fire activity in the wider region of Venezuela using MODIS satellite observations. The variability of biomass burning is most likely linked to the El Niño–Southern Oscillation (ENSO). Low biomass burning activity in the Venezuelan savannah was observed to follow La Niña conditions, high biomass burning activity followed El Niño conditions.http://www.atmos-chem-phys.net/13/9837/2013/acp-13-9837-2013.pdf |
| spellingShingle | T. Hamburger M. Matisāns P. Tunved J. Ström S. Calderon P. Hoffmann G. Hochschild J. Gross T. Schmeissner A. Wiedensohler R. Krejci Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela – sources, impacts and interannual variability Atmospheric Chemistry and Physics |
| title | Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela – sources, impacts and interannual variability |
| title_full | Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela – sources, impacts and interannual variability |
| title_fullStr | Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela – sources, impacts and interannual variability |
| title_full_unstemmed | Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela – sources, impacts and interannual variability |
| title_short | Long-term in situ observations of biomass burning aerosol at a high altitude station in Venezuela – sources, impacts and interannual variability |
| title_sort | long term in situ observations of biomass burning aerosol at a high altitude station in venezuela ndash sources impacts and interannual variability |
| url | http://www.atmos-chem-phys.net/13/9837/2013/acp-13-9837-2013.pdf |
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