The aerosol distribution in Europe derived with the Community Multiscale Air Quality (CMAQ) model: comparison to near surface in situ and sunphotometer measurements V. Matthias GKSS Research Center, Institute for Coastal Research, Max-Planck-Straß e 1, 21502 Geesthacht, Germany
Abstract. The aerosol distribution in Europe was simulated with the Community
Multiscale Air Quality (CMAQ) model system version 4.5 for the years 2000 and 2001.
The results were compared with daily averages of PM10 measurements taken
in the framework of EMEP and with aerosol optical depth (AOD) values measured
within AERONET. The modelled total aerosol mass is typically about 30–60%
lower than the corresponding measurements. However a comparison of the chemical
composition of the aerosol revealed a considerably better agreement between the
modelled and the measured aerosol components for ammonium, nitrate and sulfate,
which are on average only 15–20% underestimated. Sligthly worse agreement
was determined for sea salt, that was only avaliable at two sites. The largest
discrepancies result from the aerosol mass which was not chemically specified
by the measurements. The agreement between measurements and model is better in
winter than in summer. The modelled organic aerosol mass is higher in summer
than in winter but it is significantly underestimated by the model. This
could be one of the main reasons for the discrepancies between measurements and model
results. The other is that primary coarse particles are underestimated in the emissions.
The probability distribution function of the PM10 measurements follows
a log-normal distribution at most sites. The model is only able to reproduce
this distribution function at non-coastal low altitude stations.
The AOD derived from the model results is 20–70% lower than the values
observed within AERONET. This is mainly attributed to the missing aerosol
mass in the model. The day-to-day variability of the AOD and the log-normal
distribution functions are quite well reproduced by the model. The seasonality
on the other hand is underestimated by the model results because better agreement
is achieved in winter.
Citation: Matthias, V.: The aerosol distribution in Europe derived with the Community Multiscale Air Quality (CMAQ) model: comparison to near surface in situ and sunphotometer measurements, Atmos. Chem. Phys., 8, 5077-5097, doi:10.5194/acp-8-5077-2008, 2008.