Black carbon over the Amazon during SAMBBA: it gets everywhere

Friday, 19 December 2014: 11:35 AM
William Morgan1, James D Allan2,3, Michael Flynn3, Eoghan Darbyshire1, Dantong Liu3, Kate Szpek4, Justin Langridge4, Ben Thomas Johnson4, Jim Haywood4,5, Karla Longo6, Paulo Artaxo7 and Hugh Coe1, (1)University of Manchester, School of Earth, Atmospheric and Environmental Sciences, Manchester, M13, United Kingdom, (2)The National Centre for Atmospheric Science, University of Manchester, Manchester, United Kingdom, (3)University of Manchester, School of Earth, Atmospheric and Environmental Sciences, Manchester, United Kingdom, (4)Met Office, Exeter, United Kingdom, (5)University of Exeter, Exeter, United Kingdom, (6)INPE National Institute for Space Research, Sao Jose dos Campos, Brazil, (7)USP University of Sao Paulo, São Paulo, Brazil
Biomass burning represents a major source of Black Carbon (BC) aerosol to the atmosphere, which can result in major perturbations to weather, climate and ecosystem development. Large uncertainties in these impacts prevail, particularly on regional scales. One such region is the Amazon Basin, where large, intense and frequent burning occurs on an annual basis during the dry season. Absorption by atmospheric aerosols is underestimated by models over South America, which points to significant uncertainties relating to BC aerosol properties. Results from the South American Biomass Burning Analysis (SAMBBA) field experiment, which took place during September and October 2012 over Brazil on-board the UK Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 research aircraft, are presented here. Aerosol chemical composition was measured by a DMT Single Particle Soot Photometer (SP2) and an Aerodyne Aerosol Mass Spectrometer (AMS). The physical, chemical and optical properties of BC-containing particles across the region will be characterised, with particular emphasis on the vertical distribution.

BC was ubiquitous across the region, with measurements extending from heavily deforested regions in the Western Amazon Basin, through to agricultural fires in the Cerrado (Savannah-like) region and more pristine areas over the Amazon Rainforest. Measurements in the vicinity of Manaus (a city located deep into the jungle) were also conducted. BC concentrations peaked within the boundary layer at a height of around 1.5km. BC-containing particles were found to be rapidly coated in the near-field, with little evidence for additional coating upon advection and dilution. Biomass burning layers within the free troposphere were routinely observed. BC-containing particles within such layers were typically associated with less coating than those within the boundary layer, suggestive of wet removal of more coated BC particles. The importance of such properties in relation to the optical properties of BC and its resultant impact will be investigated. The prevalence of elevated biomass burning layers above the frequent build-up of shallow cumulus clouds during the afternoon will also be characterised. This will provide improved constraint upon the highly uncertain impact of biomass burning aerosol over the region.