Météo-France New NWP Models in Tropical Regions

Météo-France provides the main French overseas territories (Guadeloupe, Martinique, French Guiana, La Réunion, New Caledonia, and French Polynesia) with forecast products from both global and regional numerical weather prediction systems.

Five new regional systems, using AROME model, have been deployed in early 2016, bringing an important added value for both weather and cyclone forecasting. The AROME model has a nonhydrostatic dynamical model core and detailed moist physics designed for kilometric-resolution forecasts ; it has been in operations over Western Europe since 2009. Each of the five domains covers an area ranging from 1250 to 4000 km wide. The vertical resolution is characterized by 90 vertical layers starting at 5m, and a regular 2.5-km resolution is used on the horizontal, allowing explicit deep convection. This first operational version of the Tropics AROME models uses deterministic global model from ECMWF (HRES) as initial conditions and coupling model. Forecasts at +42h of lead time are performed everyday four times a day.

The first upgrade of these systems is scheduled for the end of 2017. Aside the enlargement of Arome Antilles domain, that will encompass Hispaniola, all these models will be coupled to a 1D-ocean model, initialized by Mercator-Ocean global model.

The performance of these Arome systems will be shown, with a special focus on rain and on TC forecasting. Future improvements will be discussed, such as a fine tuning of sea/air turbulent fluxes, the implementation of a 3D-Var data assimilation scheme, or an upgrade of the ocean model to a 3D one.