CMEM: Community Microwave Emission Modelling Platform

Welcome to the CMEM site

The Community Microwave Emission Modelling Platform (CMEM) has been developed by the European Centre for Medium-Range Weather Forecasts (ECMWF) as the forward operator for low frequency passive microwave brightness temperatures (from 1GHz to 20 GHz) of the surface.

It is a highly modular software package providing I/O interfaces for the Numerical Weather Prediction Community. CMEM's physics is based on the parameterizations 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). CMEM modularity allows considering different parameterizations of the soil dielectric constant as well as different soil approaches (either coherent of incoherent) and different effective temperature, roughness, vegetation and atmospheric contribution opacity models.

For the atmospheric radiative transfer calculations the RTTOV [Radiative Transfer model for Television Infrared Orbiting Satellite (TIROS) Operational Vertical Sounder (TOVS); Saunders et al. 1999] software package has been developed as a community model. It is updated and maintained by the UK Met Office under the framework of EUMETSAT's NWP Satellite Application Facility (SAF). For the ocean emissivity the fast emissivity model (FASTEM; Deblonde 2000) is available but there is currently no comparable module for the computation of land surface emissivities. Although CMEM has been designed for frequencies below 20 GHz, it's modular structure allows upgrades to higher frequencies and it is envisaged to integrate CMEM into the RTTOV software package.

CMEM is a useful tool for the SMOS calibration and validation phase, when individual SMOS Validation and Retrieval Team (SVRT) members modify parameterizations, develop new algorithms and calibrate existing ones. The results, which are mainly valid on the local to regional scale, can be implemented in CMEM and distributed to the users (Fig. 1). The users can then test the impact of the changes and provide feedback to the SVRT and ESA. CMEM is a framework ensuring a timely and direct exchange of information between the SVRT, ESA and the NWP community.