1Chinese Academy of Meteorological Science, China Meteorological Administration, Beijing, China
2Nansen-Zhu International Research Centre, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
3Graduate University of Chinese Academy of Sciences, Beijing, China
Received: 25 Dec 2008 – Discussion started: 25 Feb 2009
Abstract. We investigated aerosol hygroscopic growth property and its influence on scattering coefficient using M9003 nephelometers in coupling with humidity controlled inlet system at a rural site near Beijing mega-city from 24 April to 15 May 2006. Inlet relative humidity was controlled in an increasing range of 40%–90% while aerosol hygroscopic growth factor of scattering coefficient, f(RH=80%) as ratio of scattering coefficient at RH=80% to "dry" scattering coefficient (RH<40%) varied in a range of 1.07–2.35 during the measurement. Further analysis indicated that under dust episode, measured f(RH=80%) is 1.2±0.02, and estimated periodic mean value of f(RH=80%) was 1.31±0.03 under clean periods; during urban pollution periods, the aerosol displayed relative strong water absorbing properties with f(RH=80%) of about 1.57±0.02. An examination of chemical composition of daily filter samples highlighted that aerosol hygroscopicity was generally depressed with the increasing ratio of organic matter (OMC)/ammonium sulfate (AS) in particle mass, similar with the results of many previous studies. However, a special case with high value of f(RH=80%)=2.21 and high OMC/AS ratio was also observed, this exception reflected physico-chemical particularities of organic matter and its complex interaction with other compounds during this episode.
Revised: 26 Jul 2009 – Accepted: 30 Jul 2009 – Published: 09 Oct 2009
Pan, X. L., Yan, P., Tang, J., Ma, J. Z., Wang, Z. F., Gbaguidi, A., and Sun, Y. L.: Observational study of influence of aerosol hygroscopic growth on scattering coefficient over rural area near Beijing mega-city, Atmos. Chem. Phys., 9, 7519-7530, doi:10.5194/acp-9-7519-2009, 2009.