HR: 1340h
AN: A23C-0807    [Abstracts]
TI: Origins and Impacts of Arctic Soot: A GISS ModelE Experiment
AU: * Koch, D
EM: dkoch@giss.nasa.gov
AF: Columbia University, 2880 Broadway, New York, NY 10025 United States
AU: * Koch, D
EM: dkoch@giss.nasa.gov
AF: Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 United States
AU: Hansen, J
EM: jhansen@giss.nasa.gov
AF: Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 United States
AB: The fragile Arctic is especially susceptible to the impacts of particles and other pollution. These may affect the radiative balance there, shifting temperature profiles, clouds and precipitation. Absorbing particles such as black carbon or soot may accelerate ice and snow melting. Studies of Arctic pollution typically implicate northern Eurasia, primarily Russia and Europe, as the primary sources of emissions that reach the Arctic. However, the predominant global source of industrial black carbon emissions is estimated to come from the Far East (20%). Another substantial but distant emission is from low latitude biomass burning (50%). We use the Goddard Institute for Space Studies (GISS) General Circulation Model (GCM) to investigate the origins of Arctic black carbon (BC) by isolating various source regions and types. We permit the BC to affect the model ice/snow albedo. The model suggests that the predominant sources of Arctic soot today are indeed these distant regions. The model's Arctic BC optical thickness is mostly from the Far East (30%) and from biomass (28%, with slightly more than 1/2 coming from north of 40N); North America, Russia and Europe each contribute 10-15%. Transport from the Far East and distant biomass regions involves lofting of BC aerosols to high altitudes where they may be transported pole-ward. Thus it differs from the classic `low altitude, winter-springtime Arctic haze' transport, presently believed to be the primary mechanism responsible for bringing pollution to the Arctic. The model does confirm the importance of Russian and European contributions to the low-altitude springtime Arctic haze transport, however it indicates that the Far East also contributes substantially (all 3 regions contribute 20-25%). In the Arctic upper troposphere/lower stratosphere during the springtime, we find that the Far East (30-50%) and low latitude biomass (20-30%) are dominant, with a significant aircraft contribution (10-20%). Substantial uncertainties result from the estimated sources, model vertical mixing and aerosol removal processes. Nevertheless, our results suggest that greater consideration of the distant sources and pathways of Arctic pollution is needed. We implement a scheme that allows model soot to affect ice and snow albedo and therefore ice/snow cover, radiation and climate. We will present the model radiative forcing due to BC in the atmosphere as well as the indirect ice/snow forcing.
DE: 4801 Aerosols (0305)
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0345 Pollution--urban and regional (0305)
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting