HR: 10:20h
AN: A41F-01    [PDF]
TI: The Dominance of Organic Aerosols During NEAQS 2002
AU: * Bates, T S
EM: tim.bates@noaa.gov
AF: NOAA Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AU: Quinn, P K
EM: Patricia.K.Quinn@noaa.gov
AF: NOAA Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AU: Middlebrook, A M
EM: amiddlebrook@al.noaa.gov
AF: NOAA Aeronomy Laboratory, 325 Broadway, R/AL 7, Boulder, CO 80305 United States
AB: Aerosol chemical, physical and optical measurements were made aboard the NOAA RV Ronald H. Brown off the coast of New England during July/August 2002 as part of the New England Air Quality Study (NEAQS). Measurements (generally 20 to 100 km from the coast) were made downwind of urban centers (NYC, Boston) and rural areas, and in air masses that had not been in contact with land for several days ("marine"). On average during NEAQS, 72$\pm$9% of the dry aerosol mass sampled 18 m above the sea surface was in the $<$ 1 $\mu$m fraction (size cut at 55% RH). This submicron fraction accounted for 84$\pm $14% of the aerosol light scattering. The major sub-micron aerosol components were ammonium sulfate and particulate organic matter (POM, defined here as 1.6 times the concentration of organic carbon). The ammonium to non-sea-salt (nss) sulfate ratio increased in the urban air masses. The mass ratio of POM to nss sulfate plus ammonium ranged from 0.38 to 8.8 with values generally higher in the rural/marine air masses. POM was the dominant aerosol component in 75% of the samples. Even considering the water associated with ammonium sulfate at ambient RH and assuming no water uptake of the POM, POM was often the major source of the regional haze. These data are similar to that found off the mid-Atlantic states during TARFOX but contrary to the current understanding that the New England haze is primarily a result of sulfate aerosol. The data raise two important questions: Are these data representative of "normal" conditions along the New England Coast? And, what is the source of the POM? We can not address the first question from our single cruise but will attempt to address the latter using other measurements made aboard the ship. We will address both questions during the summer of 2004 using ship and aircraft measurements in this region along with a more detailed study of the organic POM species.
UR: http://www.al.noaa.gov/NEAQS/
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0345 Pollution--urban and regional (0305)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting