Summary:
In the present study new parameterizations are realized for developing a new
dust emission scheme to include the dynamic features of each soil type. For
this purpose is applied new categorization of soil types, representative of
arid regions. The above are implemented with the regional atmospheric model for
weather forecast SKIRON/Dust, as developed at University of Athens. Two model’s
editions are implemented, the one with operational (standard edition) and the
other with updated dust emission scheme. Standard edition uses STATGO database
of Miller and White (1998) for soil characterization and D’Almeida’s (1987)
source modes for attributed size distribution. The database of Marticorena et
al. 1997 and Laurent et al. 2008a. is utilized for the updated scheme. Every
soil type can be represented by four logarithmic distribution (for particles
with diameter greater than 80 μm), with different mass fraction for each one.
Source modes are redefined through Alfaro and Gomes (2001) distributions,
adjusted to the above database. The simulations are focused in the region of
N.Africa and Mediterranean, in order to investigate the performance of
emission schemes during production and transportation of dust particles for
the period of April-May-June of 2006, where the dust transfer is the maximum
possible. Quantitative evaluation of the basic features is made through
satellite images of Terra and Aqua MODIS. Sensitivity test are also performed
for the major dust events of the study period, while a set of statistical tools
is used for quantitative evaluation through aerosol optical depth at 550 nm,
provided by the AERONET network. The evaluation of results has shown better
representation of source’s spatial distribution in N.Africa and of attributable
dust production from the updated emission scheme. Despite the overall improved
performance with the new scheme, the analysis also showed an overestimation of
dust production for May over N.Algeria. This behavior is connected with the
frequency of dust events and the atmospheric conditions near the surface,
indicating that a different definition of sandblasting efficiency with respect
to these factor would be more appropriate.
Keywords:
Aerosols, Dust, Soil type, N. Africa, Sahara
