AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Primary Biological Aerosols as Cloud Condensation Nuclei
FRANCIS POPE, Paul Griffiths, Markus Kalberer, Michael Herzog, University of Birmingham, UK.
Abstract Number: 247 Working Group: Bioaerosols: Characterization and Environmental Impact
Abstract Primary biological aerosols (PBAs) represent a significant fraction of the total atmospheric aerosol mass burden. The low number density of PBA precludes a significant direct effect on the radiative budget of the Earth. However, the large particle size of PBA should allow them to have a significant indirect radiative effect on cloud processes if they are wettable. In particular, PBA may preferentially activate as cloud condensation nuclei (CCN) when compared to the smaller background aerosol. This effect will be most pronounced under pristine conditions where the background aerosol concentrations are small and of low hygroscopicity. Recent measurements of high PBA concentration within the Amazon (Huffman et al. 2012) suggest that this region may be particularly important for PBA-cloud interactions, and hence a potential feedback between the atmosphere and biosphere could be established (Pöschl et al. 2010).
This study investigates the ability of primary biological aerosol (PBA) to influence cloud formation and precipitation dynamics. In particular, pollen grains and fungal spores have been studied using a combined laboratory and modelling approach. The laboratory studies assessed the hygroscopicity, wettability and activation of the particles. The model output data suggests that under certain atmospheric conditions the activation of PBA can significantly interfere with the activation of the fine aerosol mode thus changing cloud dynamics. This work expands upon our previously published results on pollen activation (Pope 2010, Griffiths et al. 2012).
References
Huffman et al. (2012) 12, 11997. doi:10.5194/acp-12-11997-2012
Pöschl et al. (2010) Science. 329(5998), 1513. doi:10.1126/science.1191056
Pope (2010) Environ. Res. Lett. 5, 004015. doi:10.1088/1748-9326/5/4/044015
Griffiths et al. (2012) Atmos. Sci. Lett. 13(4), 289. doi:10.1002/asl.397