Forcing Fields

Numerical Weather Prediction (NWP) outputs are necessary to run prognostic ocean models in a forced mode in near real-time. NWP global and regional systems are operated routinely in near real-time by European National Meteorological Services (NMSs) and the European Centre for Medium range Weather Forecast (ECMWF). However, high resolution satellite (in particular wind) data can be used to improve NWP derived forcing fields in the ocean analysis/assimilation step. The objectives of the surface forcing fields module are the following :

Conduct R&D activities, aiming at defining and validating an optimal way of deriving surface forcing fields from ECMWF NWP outputs for MERSEA global ocean model. In particular, these activities will characterise the errors in the meteorological fields used as an input in the “bulk” formulae, propose optimal “bulk” formulae for turbulent fluxes derived from a set of dedicated sea campaigns corresponding to various atmospheric and oceanic conditions, and assess the impact of the various surface forcing fields and formulae available by running impact experiments with a global ocean model (ORCA2);
Conduct R&D activities and implement the production of global blended wind stress and turbulent heat fluxes, combining ECMWF outputs and high resolution satellite data available in near real-time (scatterometer, infra-red and micro-wave radiometer data);

Implement the operational near real-time access to the ECMWF NWP outputs through the GODIVA server, and make available to the MERSEA system the required fields in the required formats. As a first step, they are currently made available for the passed seven days in both GRIB and NetCDF formats through a password protected ftp site (ftp.meteo.fr ; user: mersea ; password: on request).

Mean turbulent fluxes (latent heat, sensible heat in W/m² and momentum flux in N/m²) during boreal winter (DJF) over 2002-04, derived from operational ECMWF 6 hour forecasts using optimal bulk formulae.