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It is a new highly modular code providing I/O interfaces for the Numerical Weather Prediction Community. CMEM's physics is based on a range of State-Of-The-Art parametrisations, including those used in the L-Band Microwave Emission of the Biosphere (LMEB, Wigneron et al., 2007) and Land Surface Microwave Emission Model (LSMEM, Drusch et al., 2007). So, CMEM modularity allows considering different parametrisations of the soil dielectric constant as well as different soil approaches (either coherent of incoherent), different effective temperature, roughness, vegetation and atmospheric contribution opacity models.
Simulated Top of Atmosphere brightness temperature (K), at L-band, H polarization, from ECMWF operational model:
The SMOS satellite, launched on 2 November 2009, is the first instrument to provide global fields of L-band brightness temperature. SMOS brightness temperatures is used at the European Centre for Medium-Range Weather Forecasts (ECMWF) to investigate its use to analyse soil moisture through the Surface Data Assimilation System and to monitor ocean salinity. This is expected to improve the accuracy of initial conditions of the Numerical Weather Prediction (NWP) model. In turn, NWP products are of great importance for space agencies in order to derive the Level2 soil moisture and ocean salinity products. CMEM is used at ECMWF to monitor and assimilate the SMOS brightness temperature in the Integrated Forecast System (IFS).
2- Implementation
The Community Microwave Emission Modelling Platform was developed and is maintained at ECMWF in the context of an ESA contract for the SMOS mission.
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The CMEM code is organized as described in the following Figure. The main program is cmem_main.F90 in which the following tasks are addressed:
Radiative transfer computation of CMEM is modular. It is structured in four modules for soil, vegetation, snow and atmosphere. The Platform choice of different models physics is detailed next section. The scheme below summarizes this structure.
4- Platform models physics
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