Introducing the concept of Potential Aerosol Mass (PAM) E. Kang1, M. J. Root1, D. W. Toohey2, and W. H. Brune1 1Department of Meteorology, Pennsylvania State University, University Park, PA 16802, USA 2Atmospheric and Oceanic Sciences, University of Colorado, CO 80309-0311, USA
Abstract. Potential Aerosol Mass (PAM) can be defined as the
maximum aerosol mass that the oxidation of precursor gases produces. In the
measurement, all precursor gases are rapidly oxidized with extreme amounts
of oxidants to low volatility compounds, resulting in the aerosol formation.
Oxidation occurs in a small, simple, flow-through chamber that has a short
residence time and is irradiated with ultraviolet light. The amount of the
oxidants ozone (O3), hydroxyl (OH), and hydroperoxyl (HO2) were
measured directly and can be controlled by varying the UV light and the
relative humidity. Maximum values were 40 ppmv for O3 500 pptv for OH,
and 4 ppbv for HO2. The oxidant amounts are 100 to 1000 times
troposphere values, but the ratios OH/O3 and HO2/OH are similar to
troposphere values. The aerosol production mechanism and the aerosol mass
yield were studied for several controlling variables, such as temperature,
relative humidity, oxidant concentration, presence of nitrogen oxides
(NOx), precursor gas composition and amount, and the presence of acidic
seed aerosol. The measured secondary organic aerosol (SOA) yield of several
natural and anthropogenic volatile organic compounds and a mixture of
hydrocarbons in the PAM chamber were similar to those obtained in large,
batch-style environmental chambers. This PAM method is being developed for
measuring potential aerosol mass in the atmosphere, but is also useful for
examining SOA processes in the laboratory and in environmental chambers.
Citation: Kang, E., Root, M. J., Toohey, D. W., and Brune, W. H.: Introducing the concept of Potential Aerosol Mass (PAM), Atmos. Chem. Phys., 7, 5727-5744, doi:10.5194/acp-7-5727-2007, 2007.