Towards integrated modelling of atmospheric composition: approach of
the SILAM system.
M.Sofiev, J.Vira, M.Prank, J.Soares, R.Kouznetsov, P.Siljamo, J.Kukkonen
The paper presents the new generation of the System for Integrated
modeLling of Atmospheric coMposition SILAM. The new v.5 of the system
includes 5 transformation modules: CMB-based gas-phase, original scheme
for heterogeneous transformations, linearised scheme for sulphur
oxides, generalised degradation of an abstract tracer, and radioactive
decay. Two original transformation schemes for aerosols - the
equilibrium-based and the basic aerosol dynamics - are connected with
the sectional and modal representations of particle size spectrum and
with chemical transformation routines. The list of source terms
includes point and area emission source types for anthropogenic
inventories, nuclear bomb explosion, as well as the emission sub-models
for biogenic VOC, allergenic pollen, sea salt.
The model includes two sub-systems for the data assimilation: 3D- and
4D-VAR, which allow the system initialization from the observations,
dynamic adjustment of the computations to the available data, and
enable identification or adjustment of source characteristics. The
adjoints to the system transport and some chemical modules can be used
for analysis of the observational results.
The meteorological pre-processor and transport modules allow for the
application scales ranging from global down to beta-meso scale with
spatial resolution varying from degrees up to 1 km.
The system is being evaluated against available chemical and aerosol
observations in Europe and over the globe and is used for operational
forecasting of air quality in several on-going projects.