The comprehensive model system COSMO-ART – Radiative impact of aerosol on the state of the atmosphere on the regional scale Institut für Meteorologie und Klimaforschung, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
Received: 16 Mar 2009 – Published in Atmos. Chem. Phys. Discuss.: 03 Jul 2009 Abstract. A new fully online coupled model system developed for the evaluation of the
interaction of aerosol particles with the atmosphere on the regional scale
is described. The model system is based on the operational weather forecast
model of the Deutscher Wetterdienst. Physical processes like transport,
turbulent diffusion, and dry and wet deposition are treated together with
photochemistry and aerosol dynamics using the modal approach. Based on
detailed calculations we have developed parameterisations to examine the
impact of aerosol particles on photolysis and on radiation. Currently the
model allows feedback between natural and anthropogenic aerosol particles
and the atmospheric variables that are initialized by the modification of
the radiative fluxes. The model system is applied to two summer episodes,
each lasting five days, with a model domain covering Western Europe and
adjacent regions. The first episode is characterised by almost cloud free
conditions and the second one by cloudy conditions. The simulated aerosol
concentrations are compared to observations made at 700 stations distributed
over Western Europe.
Revised: 09 Oct 2009 – Accepted: 23 Oct 2009 – Published: 16 Nov 2009
For each episode two model runs are performed; one where the feedback
between the aerosol particles and the atmosphere is taken into account and a
second one where the feedback is neglected. Comparing these two sets of
model runs, the radiative feedback on temperature and other variables is
In the cloud free case a clear correlation between the aerosol optical depth
and changes in global radiation and temperature is found. In the case of
cloudy conditions the pure radiative effects are superposed by changes in
the liquid water content of the clouds due to changes in the thermodynamics
of the atmosphere. In this case the correlation between the aerosol optical
depth and its effects on temperature is low. However, on average a decrease
in the 2 m temperature is still found.
For the area of Germany we found on average for both cases a reduction in
the global radiation of about 6 W m2, a decrease of the 2 m temperature
of 0.1 K, and a reduction in the daily temperature range of −0.13 K.
Citation: Vogel, B., Vogel, H., Bäumer, D., Bangert, M., Lundgren, K., Rinke, R., and Stanelle, T.: The comprehensive model system COSMO-ART – Radiative impact of aerosol on the state of the atmosphere on the regional scale, Atmos. Chem. Phys., 9, 8661-8680, doi:10.5194/acp-9-8661-2009, 2009.