HR: 0800h
AN: A51E-0833    [Abstracts]
TI: Aerosol Radiative Properties and Their Dependence on Relative Humidity and Wavelengths during ICARTT
AU: * Wang, W
EM: weiwang@uiuc.edu
AF: University of Illinois, Department of Civil & Environmental Engineering, Urbana, IL 61801 United States
AU: Rood, M J
EM: mrood@uiuc.edu
AF: University of Illinois, Department of Civil & Environmental Engineering, Urbana, IL 61801 United States
AU: Carrico, C M
EM: carrico@lamar.colostate.edu
AF: Colorado State University, Department of Atmospheric Science, Fort Collins, CO 80523 United States
AU: Covert, D S
EM: dcovert@u.washington.edu
AF: University of Washington, Department of Atmospheric Sciences, Seattle, WA 98195 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: Bates, T S
EM: tim.bates@noaa.gov
AF: NOAA Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AB: Aerosol optical and hygroscopic properties were measured onboard the NOAA RV Ronald H. Brown as part of the ICARTT (International Consortium for Atmospheric Research on Transport and Transformation) in the Gulf of Maine during July and August of 2004. A scanning relative humidity (RH) nephelometry system was used to measure the total light scattering and backscattering coefficients by particles (\sigma$_{sp}$ and \sigma $_{bsp}$, respectively) at controlled RH with three wavelengths of scattered light ($\lambda$). Controlled RH ranged from 40$%$ to 85$%$, while the scattering coefficients were measured at 450 nm, 550 nm, and 700 nm. Measurements were completed 90$%$ of the entire field campaign. The dependence \sigma$_{sp}$ and \sigma $_{bsp}$, hemispheric backscatter fraction (b), $\AA$ngstr$ {o}$m exponent ($\aa$), and single scattering albedo ($\omega$) upon $\lambda$ and RH will be reported. The dependence of aerosol hygroscopicity on air mass type and aerosol chemical composition will be discussed along with meteorology and origin of the sampled air masses. The ambient aerosol hydration state (i.e., on the upper branch, lower branch, or intermediate to the two branches of the hysteresis loop) will also be described. These results are important to better understand the hygroscopic properties of ambient aerosol and to parameterize ambient aerosol optical properties for use in large-scale climate models.
DE: 0360 Transmission and scattering of radiation
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting