model which is the acronym for the
An upgraded version of the ALERMO model with a 1/30o of horizontal resolution was developed within the framework of MFSTEP (Mediterranean Forecasting System - Towards Environmental Predictions). ALERMO is one-way nested to a global Mediterranean OGCM (MOM, 1/16o × 1/16o) running operationally on a daily basis.
Upgraded ALERMO model characteristics in MFSTEP
Geographical area covered: 20oE – 36.4oE & 30.7oN – 41.2oN
Horizontal resolution: 1/30o × 1/30o
Vertical resolution: 25 sigma levels logarithmically distributed
Advection of tracers: Smolarkiewicz upstream scheme with anti-diffusive velocities
Open boundary conditions: One-way nesting with the 1/16o × 1/16o MFSTEP Mediterranean OGCM model running operationally. The nesting scheme has been developed within MFSPP and is based on:
- Flathers (1975) open boundary conditions for nesting of the barotropic velocities normal to the open boundaries
- Volume conservation at the open boundaries
- Direct specification of baroclinic velocities, free surface elevation and tangential barotropic velocities
- Direct specification of tracers (T/S) in case of inflow and upstream advection in the case of outflow
Atmospheric coupling: ALERMO is one-way coupled with the SKIRON weather forecasting system (LAM).
The SKIRON system provides:
· Air temperature and relative humidity at 2m above sea surface
· Wind velocity at 10m above sea surface
· Sea level atmospheric pressure
· Net shortwave radiation at the sea surface
· Downward longwave radiation
· Precipitation rate
Momentum fluxes, evaporative, upward longwave radiation and sensible heat fluxes are calculated through bulk formulae using the SST predicted by the ALERMO model.
Furthermore the upgraded version of the ALERMO model provides the atmospheric pressure loading and optional inclusion of tidal forcing
Surface freshwater flux: Real freshwater flux instead of (virtual) salt flux is used for the sea surface boundary conditions
Variational Initialization: The ALERMO model will be initialized from the MFSTEP OGCM on a weakly basis (operationally during the TOP period) using the Variational Initialization (VI) method (Auclair et al. 2000).
Data assimilation: An optimal interpolation scheme (O.I. MARK-II) will be implemented in the near future.
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