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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D23, 8650, doi:10.1029/2003JD003405, 2003

Mixtures of pollution, dust, sea salt, and volcanic aerosol during ACE-Asia: Radiative properties as a function of relative humidity

Christian M. Carrico

Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA


Pinar Kus

Department of Civil and Environmental Engineering, University of Illinois, Urbana, Illinois, USA


Mark J. Rood

Department of Civil and Environmental Engineering, University of Illinois, Urbana, Illinois, USA


Patricia K. Quinn

Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington, USA


Timothy S. Bates

Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington, USA


Abstract

The Ron Brown cruise during ACE-Asia (March–April 2001) encountered complex aerosol that at times was dominated by marine, polluted, volcanic, and dust aerosols. Average total light scattering coefficients (σsp for Dp <10 μm, relative humidity (RH) = 19%, and λ = 550 nm) ranged from 23 (marine) to 181 Mm−1 (dust). Aerosol hygroscopicity ranged from deliquescent with hysteresis (marine frequently and polluted variably) to hygroscopic without hysteresis (volcanic) to nearly hygrophobic (dust-dominated). Average deliquescence and crystallization RH were 77 ± 2% and 42 ± 3%, respectively. The ambient aerosol was typically on the upper branch of the hysteresis loop for marine and polluted air masses and the lower branch for dust-dominated aerosols. Average f(RH = ambient), defined as σsp (RH = ambient)/σsp (RH = 19%), ranged from 1.25 (dust) to 2.88 (volcanic). Average h(RH ∼60%), defined as f(RH)upper branch/f(RH)lower branch, were 1.6, 1.3, 1, and 1.25 for marine, polluted, volcanic, and dust, demonstrating an importance of hysteresis to optical properties. Hemispheric backscatter fraction (b) at ambient RH ranged from 0.077 (marine) to 0.111 (dust), while single scattering albedo (ω) at ambient RH ranged from 0.94 (dust and polluted) to 0.99 (marine).

Received 11 January 2003; accepted 8 May 2003; published 18 November 2003.

Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); 0370 Atmospheric Composition and Structure: Volcanic effects (8409); 1610 Global Change: Atmosphere (0315, 0325); 4801 Oceanography: Biological and Chemical: Aerosols (0305).

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Citation: Carrico, C. M., P. Kus, M. J. Rood, P. K. Quinn, and T. S. Bates (2003), Mixtures of pollution, dust, sea salt, and volcanic aerosol during ACE-Asia: Radiative properties as a function of relative humidity, J. Geophys. Res., 108(D23), 8650, doi:10.1029/2003JD003405.