HR: 16:40h
AN: A14C-03 INVITED     [Abstracts]
TI: Pollution Processing by California Radiation Fogs
AU: * Collett, J L
EM: collett@lamar.colostate.edu
AF: Colorado State University, 407 Atmospheric Science, Fort Collins, CO 80525 United States
AU: Herckes, P
EM: herckes@lamar.colostate.edu
AF: Arizona State University, Department of Chemistry and Biochemistry, Tempe, AZ 85287 United States
AU: Moore, K F
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Lee, T
EM: thlee@lamar.colostate.edu
AF: Colorado State University, 407 Atmospheric Science, Fort Collins, CO 80525 United States
AU: Chang, H
EM: hchang@lamar.colostate.edu
AF: Colorado State University, 407 Atmospheric Science, Fort Collins, CO 80525 United States
AU: Youngster, S
EM: sbyoungs@lamar.colostate.edu
AF: Colorado State University, 407 Atmospheric Science, Fort Collins, CO 80525 United States
AU: Reilly, J
AF: Colorado State University, 407 Atmospheric Science, Fort Collins, CO 80525 United States
AB: The San Joaquin Valley (SJV) of California has drawn attention lately for being home to several of the most polluted cities in the U.S. Elevated regional levels of airborne fine particulate matter occur especially in wintertime, when high pressure leads to air stagnation and formation of a subsidence version above the valley floor. Clear skies accompanying these winter stagnation episodes give rise to strong radiative cooling at night and frequent formation of persistent, dense fogs. The chemistry of SJV fogs and their interactions with airborne pollutants have been studied repeatedly over the past two decades. The focus was originally on interactions with sulfate and nitrate, shifting in recent years toward an understanding of fog processing of organic material. A review of key observations and findings from several recent studies of SJV fogs will be presented. SJV fogs contribute both to formation of new particle mass and to particle removal. Particle formation is known to occur via aqueous phase oxidation of sulfur dioxide and by reactions between dissolved sulfur dioxide and formaldehyde to form hydroxymethanesulfonate. Additional production of low volatility solutes from fog processing of volatile organic compounds is also likely, although poorly understood. Fog cleansing of the atmosphere occurs via drop scavenging (via nucleation and other mechanisms) of airborne particles, followed by drop deposition to the surface. Both new particle production and removal are influenced by variations in fog drop composition across the drop size spectrum. The net effect of most SJV fog episodes appears to be to cleanse the atmosphere of fine particulate matter, thereby limiting pollutant buildup during winter stagnation episodes. The effectiveness of the fogs as atmospheric cleansers depends on fog duration, depth and drop size.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
DE: 0345 Pollution--urban and regional (0305)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting