Operational implementation of the AROME model in the Tropics: multiscale validation of rainfall forecasts
Faure, Ghislain ; Chambon, Philippe ; Brousseau, Pierre
Météo-France runs operationally, for the needs of several overseas regions in the tropical belt, five numerical weather prediction configurations, based on the convection-permitting model AROME and called the AROME-OM system. These configurations use the high resolution model (IFS) from the European Centre for Medium RangeWeather Forecasts (ECMWF) for both initialization and lateral forcing. In this study, the performance of the AROME-OM system for rainfall forecasting is compared to the one of ECMWF IFS. The validation uses spatialized rainfall estimates over a 24 h time period at two time scales (daily and annual), from both satellite and ground-based instruments. It has been performed over a 10-month period and across five tropical domains. The intercomparison demonstrates consistent signals across domains and scales. The added-value of the AROME-OM system compared to ECMWF IFS is shown for rain/no-rain discrimination and for rain accumulations larger than 10mm/day. The AROME-OM system shows also a better ability to forecast realistic rain patterns over these tropical regions. The main weakness found is for an intermediate range of rain accumulations, from 1 to 10 mm/day, for which the ECMWF IFS forecasts slightly outperform the AROME-OM system forecasts.</p>
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