Contrasting Organic Aerosol Behaviour in Continental Polluted, Biomass Burning and Pristine Tropical Forest Environments

In this paper we will present new measurements of organic aerosol mass taken during the African Monsoon Multivariate Analysis (AMMA) project which took place in West Africa during 2006. The organic mass loading of biomass burning aerosols will be shown to be highly correlated with CO over a wide range of distance scales from the source region to the background. This demonstrates that there is little secondary production of organic aerosol compared to the primary emission over the lifetime of the plume. However, we will show that chemical functionality of the organic mass changes with time, indicating that the aerosol themselves are processed. Aerosol measurements in pristine tropical environments show little evidence for enhanced aerosol loadings despite very large enhancements in possible precursors, placing upper limits on the secondary organic aerosol yield in these environments. This will be compared with global model predictions. This behaviour will be will be compared with previous measurements taken in continental polluted environments.

Keywords Organic aerosols, biomass burning, tropical aerosols, secondary formation