HR: 1330h
AN: A12B-0082    [PDF]
TI: Field Measurements of Atmospheric Elemental Carbon Concentrations in the Northeastern US Over a Quarter Century
AU: * Husain, L
EM: husain@wadsworth.org
AF: Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12201-0509 United States
AU: * Husain, L
EM: husain@wadsworth.org
AF: Department of Environmental Health and Toxicology, School of Public Health, State University of New York, Albany, NY 12201-0509 United States
AU: Li, J
EM: lijj@wadsworth.org
AF: Department of Environmental Health and Toxicology, School of Public Health, State University of New York, Albany, NY 12201-0509 United States
AU: Khan, A J
EM: khan@wadsworth.org
AF: Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12201-0509 United States
AB: Elemental Carbon (EC) are black carbon aerosols in earth's atmosphere and have a warming effect as they absorb solar radiation and they may also modify cloud cover. Model calculations suggest that their role in global warming may be second only to carbon dioxide. At present, no reliable long-term atmospheric EC data are available. The EC data currently used in models to estimate radiative forcing is based on EC emissions from combustion of a variety of fossil fuels. The uncertainties are high and unacceptable. We have initiated a program that will provide accurate data at two locations in the Northeastern US for 20 to 25 years. We have continuously collected daily aerosol samples at Whiteface Mountain in New York State since July, 1978 and Mayville, ~ 530 km upwind (southwest)of Whiteface Mt. from July, 1983 to the present. Both sites are rural, with little industry and thin population. These samples have been analyzed for sulfate and their relationship with long-term regional sulfur dioxide emissions have been studied [Husain et al., Geophys. Res. Lett. 25, 967-970, 1998]. We have developed a methodology to determine EC concentrations in these filter samples using the thermal optical method [Li et al., Atmos. Env. 36, 4,699-4,704, 2002]. The EC concentrations were determined in monthly composites for 1984, 2001 and 2002 at Mayville and for 2002 at Whiteface Mt. The annual mean concentrations at Mayville for 1984, 2001, and 2002 were 0.539, 0.411 and 0.377 $\mu$g/m$^3$, respectively. Thus, a decrease of ~27 percent in EC concentration was observed over a period of ~ two decades. The EC concentration for 2002 at Whiteface Mountain was 0.070 $\mu$g/m$^3$ or approximately 6-fold lower than that for Mayville. When completed, the data would provide an invaluable source for verifying the models relating emissions from fossil fuel and biomass burning and atmospheric EC burden and in calculating radiative forcing.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
DE: 1600 GLOBAL CHANGE (New category)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting