Export efficiency of black carbon aerosol in continental outflow: Global implications

By R. Park, D. J. Jacob, Paul I. Palmer, A. Clarke, R. Weber, M. Zondlo, F. Eisele, A. Bandy, D. Thornton, G. Sachse and 1 more. 2005

230 citations recorded by the source corpus.

[1] 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 (SO x = SO 2 (g) + fine SO 2- 4 ) and total inorganic nitrate (HNO T 3 = HNO 3 (g) + fine NO - 3 ) 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 SO x (0.48-0.66) and HNO T 3 (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%.

Subfields: Atmospheric Science, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/f16e113e6fcb929e07338f7ae54a690b3de842a3

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Citations in the corpus

Aerosol light absorption and its measurement: A review (2009, background): “More recently, it has become clear that carbonaceous aerosols are much more dominant and widespread in the atmosphere than previously thought [89–93].”
Simulation of particle size distribution with a global aerosol model: contribution of nucleation to aerosol and CCN number concentrations (2009, methodology): “The scheme provides a good simulation of soluble species concentrations in the United States (Park et al., 2003; 2004) and in North American and Asian outflow (Li et al., 2005; Park et al., 2005).”