Parameterization of Aerosol Particle Hygroscopic Growth Factors
Abstract
A model was developed to fit hygroscopic growth as a function of relative humidity in order to retrieve information on aerosol particle hygroscopic properties and chemical composition. The parameters obtained are the "hygroscopicity parameter" and volume fraction for the organic components; the remainder of the aerosol is assumed to be ammonium sulphate. The model was used to analyze Hygroscopic Tandem Differential Mobility Analyzer (HTDMA) data from two field studies in southern Ontario. Comparisons between the organic fractions from the model fits and ones measured with an Aerosol Mass Spectrometer (AMS) were performed for 100 nm and 150 nm diameter particles. The two data sets generally agreed within their error limits. After validating the model at the larger sizes, it was then used to analyze HTDMA data for particle sizes of 30 and 50 nm, at which the AMS is unable to provide useful data. As with the larger particles, organic fraction often made up more than 50 percent of the total particle volume. The organic hygroscopicity parameter was typically in the range of 0.01 to 0.37; this is in agreement with values obtained in previous studies.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2009
- Bibcode:
- 2009AGUSM.A23A..02Z
- Keywords:
-
- 0305 Aerosols and particles (0345;
- 4801;
- 4906);
- 0320 Cloud physics and chemistry;
- 0345 Pollution: urban and regional (0305;
- 0478;
- 4251);
- 0365 Troposphere: composition and chemistry