The AEROCOM-project is an open international initiative of
scientists interested in the advancement of the understanding
of the global aerosol and its impact on climate. A large number
of observations (including MODIS, POLDER, MISR, AVHHR, SEAWIFS,
TOMS, AERONET and surface concentrations) and results from
more than 14 global models have been assembled to document
and compare state of the art modeling of the global aerosol.
A common protocol
has been established and models are asked to make use of the
emission inventories for the year 2000 and preindustrial
times. Results are documented via interactive
websites which give access to 2D fields and standard comparisons
to observations. Regular workshops
are held to discuss findings and future directions.
Multi-component aerosol modules in global models promise
a much needed better seasonal and regional characterization
of aerosol. However, the added complexity may have introduced
many (potentially offsetting) errors. Thus, a rigorous validation
effort is needed. Initial comparisons model evaluation efforts
to remote sensing data (e.g. Kinne et al and Penner et al)
illustrated the need for more detailed comparisons. Only a
much expanded model output will permit process studies, like
pioneering comparisons of near surface sulfate mass (COSAM).
This study also indicated that unwanted difficulties arise
from differences in model initialization (e.g. source strength
or meteorology). Concepts of a new model-intercomparison and
model-evaluation effort were discussed during IAMAP 2001 and
introduced to modelers or interested by-standers during IGAC
2002. A driving force behind the new inter-comparison is availability
of more accurate aerosol products from satellite, a tighter
ground network of aerosol measurements and a multitude of
results from field experiments.