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Park et al. 2005
Park, R.J., Jacob, D.J., Palmer, P.I., Clarke, A.D., Weber, R.J., Zondlo, M.A., Eisele, F.L., Bandy, A.R., Thornton, D.C., Sachse, G.W. and Bond, T.C. (2005). Export efficiency of black carbon aerosol in continental outflow: Global implications. Journal of Geophysical Research 110: doi: 10.1029/2004JD005432. issn: 0148-0227.

We use aircraft observations of Asian outflow from the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) mission over the NW Pacific in March--April 2001 to estimate the export efficiency of black carbon (BC) aerosol during lifting to the free troposphere, as limited by scavenging from the wet processes (warm conveyor belts and convection) associated with this lifting. Our estimate is based on the enhancement ratio of BC relative to CO in Asian outflow observed at different altitudes and is normalized to the enhancement ratio observed in boundary layer outflow (0--1 km). We similarly estimate export efficiencies of sulfur oxides (SOx = SO2(g) + fine SO42-) and total inorganic nitrate (HNO3T = HNO3(g) + fine NO3-) for comparison to BC. Normalized export efficiencies for BC are 0.63--0.74 at 2--4 km altitude and 0.27--0.38 at 4--6 km. Values at 2--4 km altitude are higher than for SOx (0.48--0.66) and HNO3T (0.29--0.62), implying that BC is scavenged in wet updrafts but not as efficiently as sulfate or nitrate. Simulation of the TRACE-P period with a global three-dimensional model (GEOS-CHEM) indicates that a model timescale of 1 ¿ 1 days for conversion of fresh hydrophobic to hydrophilic BC provides a successful fit to the export efficiencies observed in TRACE-P. The resulting mean atmospheric lifetime of BC is 5.8 ¿ 1.8 days, the global burden is 0.11 ¿ 0.03 Tg C, and the decrease in Arctic snow albedo due to BC deposition is 3.1 ¿ 2.5%.

BACKGROUND DATA FILES

Abstract

Keywords
Atmospheric Composition and Structure, Aerosols and particles (0345, 4801, 4906), Atmospheric Composition and Structure, Pollution, urban and regional (0305, 0478, 4251), Atmospheric Composition and Structure, Troposphere, constituent transport and chemistry, export efficiency, black carbon aerosol, BC solubility
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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