In-situ airborne observations by the FAAM BAE-146 aircraft for South AMerican Biomass Burning Analysis (SAMBBA).

SAMBBA project - a UK-Brasil Consortium funded by NERC. Biomass burning aerosols have a significant influence on climate – both directly as they scatter and absorb solar radiation – and indirectly as they influence cloud optical properties and lifetime through their ability to act as sites for cloud droplet formation. Biomass burning aerosols are a complex mixture of black carbon, organic carbon, and inorganic compounds, and are thus difficult to model accurately. While parameterisations have been developed in the climate version of the UM (e.g. HADGEM-2) that enable reasonable representation of the aerosol optical depth, significant uncertainties still exists in accurately determining the aerosol absorption (via the single scattering albedo) and the subsequent effects on radiation. These radiative effects have a significant impact on climate, which needs to be quantified over key regions such as Amazonia. Furthermore, BB aerosols have a direct impact on the performance of numerical weather prediction models. The effects of biomass burning aerosol upon cloud microphysical and optical properties play a significant role in assessing the radiative influence of clouds. These are also processes that are poorly quantified and hence provide fundamental uncertainties in weather forecasts and climate change scenarios. To improve quantification of these uncertainties, the microphysical and chemical properties of biomass burning aerosol and its precursors need to be determined yet these remain uncertain and are known to be modified during their lifetime in the atmosphere. Furthermore, it is important to assess the background state of the atmosphere in the region to understand the influence such large anthropogenic perturbations are having on the region. However, aerosol particles in the natural tropical atmosphere remain poorly understood.

The aim of the SAMBBA project was to investigate the properties of biomass burning aerosols over South America. The main biomass burning season occurs during Sept/Oct when deforestation fires and agricultural burning are prolific, particularly over central and south eastern parts of Brazil. These contribute to high loadings of biomass burning aerosol over much of South America with aerosol optical depths frequently exceeding 1 in many central parts of the continent. SAMBBA was a consortium of 7 university groups, the UK Met Office and a number of Brazilian partners, which delivered a suite of ground, aircraft and satellite measurements of Amazonian BBA and use this data to:

-improve our knowledge of BB emissions;
-challenge and improve the latest aerosol process models;
-challenge and improve satellite retrievals;
-test predictions of aerosol influences on regional climate and weather over Amazonia and the surrounding regions made using the next generation of climate and NWP models with extensive prognostic aerosol schemes; and
-assess the impact of biomass burning on the Amazonian biosphere.