Simulating aerosol microphysics with the ECHAM4/MADE GCM – Part II: Results from a first multiannual simulation of the submicrometer aerosol A. Lauer and J. Hendricks DLR Institute of Atmospheric Physics, Oberpfaffenhofen, 82234 Wessling, Germany
Abstract. First results of a multiannual integration with the new global aerosol
model system ECHAM4/MADE are presented. This model system enables
simulations of the particle number concentration and
size-distribution, which is a fundamental innovation compared to
previous global model studies considering aerosol mass cycles
only. The data calculated by the model provide detailed insights into the
properties of the global submicrometer aerosol regarding global
burden, chemical composition, atmospheric residence time, particle number
concentration and size-distribution.
The aerosol components considered by the model are
sulfate (SO4), nitrate
(NO3), ammonium (NH4), black carbon (BC),
organic matter (OM), mineral dust, sea salt and aerosol water. The
simulated climatological annual mean global atmospheric burdens
of the dominant submicrometer aerosol components are 2.25 Tg (4.5 d)
for SO4, 0.46 Tg (4.5 d) for NH4,
0.26 Tg (6.6 d) for BC, and 1.77 Tg (6.5 d) for OM.
The contributions of individual processes such as emission,
nucleation, condensation or dry and wet deposition to the global
sources and sinks of specific aerosol components and particle number
concentration are quantified. Based on this analysis, the significance
of aerosol microphysical
processes (nucleation, condensation, coagulation)
is evaluated by comparison to the importance of other processes relevant
for the submicrometer aerosol on the global scale. The results reveal that
are essential for the simulation of the particle number
concentration and important but not vital for the simulation of particle mass
concentration. Hence aerosol
should be taken into account in
simulations of atmospheric processes showing a significant dependence
on aerosol particle number concentration.
The analysis of the vertical variation of the microphysical net production
and net depletion rates performed for particle number
concentration, sulfate mass and black carbon mass concentration
unveils the dominant source and sink regions. Prominent features can
be attributed to dominant microphysical processes such as nucleation
in the upper troposphere or wet deposition in the lower troposphere.
Regions of efficient coagulation can be identified.
Citation: Lauer, A. and Hendricks, J.: Simulating aerosol microphysics with the ECHAM4/MADE GCM – Part II: Results from a first multiannual simulation of the submicrometer aerosol, Atmos. Chem. Phys., 6, 5495-5513, doi:10.5194/acp-6-5495-2006, 2006.