Regional and intercontinental modelling - Air Pollution Modeling and Its Application - page 241

Fig. 3. Column-integrated predicted and measured AOD averaged over 2001. Left-hand panel:
AOD caused by the sea salt concentrations predicted by SILAM; right-hand panel: observed by
the NASA MODIS instrument
Higher predicted sea salt concentrations and measured AOD occurred in the
southern hemisphere, where there is a larger fraction of sea area, and the wind
velocities are higher. The comparisons with EMEP data show that SILAM tends
to over-predict the sea-salt concentrations, in average, staying within a factor of 2
from the concentrations.
4. Conclusions
The basic chemical transformation scheme captures the main features of the
inorganic species and their reactions. The ozone-formation mechanisms require
further development. The sea salt emission parameterisation seems to predict fairly
well the spatial and temporal variation for the considered particle size ranges.
However, the new model for sea salt production over-estimates both near-surface
concentrations, where the coarse mode plays the main role, and also the column-
integrated optical density, which is primarily influenced by fine particles.
Acknowledgments The financial support by the GEMS and PROMOTE projects, the Maj and
Tor Nessling Foundation and COST ES0602 is gratefully acknowledged.
References
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