HR: 0800h
AN: A51E-0832    [Abstracts]
TI: Visibility, Aerosol Concentrations, and Relative Humidity
AU: * Brown, N J
EM: njbrown@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Road 51R0208, Berkeley, CA 94720
AU: Liu, D
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Road 51R0208, Berkeley, CA 94720
AU: Lunden, M M
EM: mmlunden@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Road 51R0208, Berkeley, CA 94720
AU: Tonse, S R
EM: tonse@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Road 51R0208, Berkeley, CA 94720
AB: Transported aerosols from populated and industrial areas result in regional haze that causes visibility degradation in areas valued for their scenic beauty, such as the National Parks. These areas are designated as Class I Areas in the United States, and there are specific visibility goals put forth to ultimately return these areas to natural conditions. It is important to understand the role of meteorological factors on the extinction of visible light to achieve this goal. The objective of this research is to explore the contributory role played by relative humidity on visibility degradation using the field data collected by us in Central California from the intensive ambient aerosol sampling campaign conducted from 2000 summer-2001-2002 winter1. The data include PM-2.5 nitrate, sulfate, and carbon mass concentrations, as well as simultaneous measurements on light scattering, light absorption, ambient temperature and relative humidity. The dataset is highly time-resolved, allowing the affect of temporal variations of particle chemical composition and meteorological features to be considered. The effect of relative humidity on visibility reduction has been explored by statistical analysis of this data. The final results provide response curves that allow calculation of light scattering and absorption, given aerosol concentrations and relative humidity. Our results are compared with those obtained using formulae suggested for analysis of IMPROVE data collected under conditions of low temporal resolution to understand the affects of temporal resolution on the characteristics of the relationships among extinction, aerosol loading and type, and relative humidity. IMPROVE is a monitoring network established with the goal of monitoring regional haze in many of the Class I areas. References 1. Lunden, M.M., T.L. Thatcher, S.V. Hering, and N.J. Brown (2003). The Use of Time- and Chemically-Resolved Particulate Data to Characterize the Infiltration of Outdoor PM-2.5 into a Residence in the San Joaquin Valley. Environmental Science and Technology 37, pp 4724-4732. 2. Malm, W.C., "IMPROVE, Interagency Monitoring of Protected Visual Environments," ISSN: 0737-5352-47, Colorado State University, May 2000.
DE: 0360 Transmission and scattering of radiation
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting