(70d) Inferring New Particle Formation and Growth From Measurements of Aerosol Properties

Aerosols play an important role in Earth’s radiation balance and their climate forcing effects represent the largest uncertainties in the Intergovernmental Panel on Climate Change’s 2007 fourth assessment report.  The nucleation and growth of gas phase molecules into liquid or solid phase particles is the main source of ultrafine aerosol particles in the atmosphere. The complicated underlying physical properties and conditions for nucleation are not well understood.  While data on nucleation is limited both temporally and spatially, data on atmospheric particle number concentration is readily available in many locations.  Our current goal is to improve methods of data analysis in order to infer information about new particle formation and growth from long term measurements of particle number and other aerosol properties.  As a test case, we investigate a five year (2006 – 2010) record of 1 minute particle number concentration data from Bondville, IL to infer nucleation rates in rural continental environments. The probability of nucleation can be quantified by optimization of agreement between possible size distributions (constrained in total number by observations) and collocated optical and physical measurements.  The suggesting of an aerosol size distribution will be aided by data from a 2005 field campaign in which the aerosols size distribution was measured.  Parallel efforts at modeling the nucleation activity will also be discussed.