Simulating the global atmospheric black carbon cycle: a revisit to the contribution of aircraft emissions J. Hendricks1, B. Kärcher1, A. Döpelheuer2, J. Feichter3, U. Lohmann4,*, and D. Baumgardner5 1DLR-Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany 2DLR-Institut für Antriebstechnik, Köln, Germany 3Max-Planck-Institut für Meteorologie, Hamburg, Germany 4Dalhousie University, Halifax, Canada 5Centro de Ciencias de la Atmósfera, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico *now at: ETH, Institut für Atmosphäre und Klima, Zürich, Switzerland
Abstract. The black carbon (BC) burden of the upper
troposphere and lowermost stratosphere (UTLS) is investigated
with the general circulation model (GCM) ECHAM4. The special focus is
the contribution of aircraft emissions to the UTLS BC loading.
Previous studies on the role of aircraft emissions in the global BC cycle
either neglect BC sources located at the Earth's surface or simplify
the BC cycle by assuming pre-defined BC residence times. Here,
the global BC cycle including emissions, transport, and removal
is explicitly simulated. The BC emissions considered include
surface sources as well as BC from aviation. This enables a consistent
calculation of the relative contribution of aviation to the global atmospheric
BC cycle. As a further extension to the previous studies, the aviation-induced
perturbation of the UTLS BC particle number concentration is investigated.
The uncertainties associated with the model predictions are evaluated
by means of several sensitivity studies. Especially, the sensitivity of the
results to different assumptions on the BC hygroscopic properties is analysed.
The simulated UTLS BC concentrations are compared to in-situ observations.
The simulations suggest that the large-scale contribution of aviation
to the UTLS BC mass budget typically amounts to only a few percent, even in
the most frequented flight regions. The aviation impact far away from
these regions is negligible. The simulated aircraft contributions to the
UTLS BC particle number concentration are much larger compared to the
corresponding mass perturbations. The simulations suggest that aviation can
cause large-scale increases in the UTLS BC particle number concentration
of more than 30% in regions highly frequented by aircraft.
The relative effect shows a pronounced annual variation with
the largest relative aviation impact occurring during winter.
Citation: Hendricks, J., Kärcher, B., Döpelheuer, A., Feichter, J., Lohmann, U., and Baumgardner, D.: Simulating the global atmospheric black carbon cycle: a revisit to the contribution of aircraft emissions, Atmos. Chem. Phys., 4, 2521-2541, doi:10.5194/acp-4-2521-2004, 2004.