ATMOSPHERE & CLIMATE DYNAMICS GROUP

DEPARTMENT OF GEOGRAPHY-HAROKOPIO UNIVERSITY OF ATHENS

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The limited area WRF-ARW-CHEM v3.6 meteorology-chemistry model has been installed and configured at the parallel computational infrastructure of the Geography Department  of Harokopio University of Athens (HUA) since July 2014. The GOCART (Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport model, Chin et al., JGR, 2000) aerosol module that is used has a sectional scheme for dust, providing forecast for five particle-size bins: 0.5, 1.4, 2.4, 4.5, 8.0 μm effective radius. The model produces  a 72-hour (3 days) dust forecasts (near surface dust concentration, total dust load and dust dry deposition) covering the North Africa, Europe, Middle East and the Saudi Arabia peninsula. The operational domain is consisted of 400x212 grid points, on a 25x25 km grid distance, with 38 vertical levels up to 25 hPa. The dust sources are primarily derived from the clay and sand fraction databases.
CLAYFRACSANDFRAC

The GOCART aerosol module has also a sectional scheme for sea salt, providing forecast for four particle-size bins: 0.3, 1.0, 3.2, 7.5 μm effective radius, concerning the the entire dust operational domain. The calculation of  the sea salt flux is based on the original formula by Monahan et. al (1986) which expresses the rate of seawater droplet generation per unit area of sea surface, per increment of particle radius and it reasonably predicts total sea-salt aerosol mass concentrations and their wind dependence (Gong, 2003) for sea-salt aerosols larger than 0.2 μm radius. The new version is better to represent emission of sub-micron sea salt particles and reduces the sea-salt number flux density below 0.2 μm radius. It also maintains the basic form of the original Monahan equation but adds a size-dependent exponential term for radius.

 

Chin, M., R. B. Rood, S.-J. Lin, J.-F. Müller, and A. M. Thompson (2000), Atmospheric sulfur cycle simulated in the global model GOCART: Model description and global properties, J. Geophys. Res., 105(D20), 24671–24687, doi:10.1029/2000JD900384.
Gong, S. L., A parameterization of sea-salt aerosol source function for sub- and super-micron particles, Global Biogeochem. Cycles, 17(4), 1097, doi:10.1029/2003GB002079, 2003.
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