Real-Time Drought Monitoring: From Analysis To Seasonal Forecast

Since 2003, Meteo-France operates in real-time a hydro-meteorological model chain used to monitor the hydrological situation. The SAFRAN atmospheric analysis drives the ISBA land surface model. The latter feeds a hydrological model called MODCOU. The original version of SIM (SAFRAN-ISBA-MODCOU) was updated in 2016 to improve the radiative forcing from SAFRAN, soil modelling, sub-grid processes representation. Besides the real-time application, a reanalysis has been performed to cover years from 1958 in order to characterize the water resources monitoring precipitation, soil wetness, snow water equivalent. In the meantime, forecast applications have been developed to document the expected evolution of the hydrological context. Hydrological initial states come from the real-time analysis and meteorological forecasts drive the hydrological ISBA-MODCOU component. Using 10-days meteorological forecasts from ECMWF (European Centre for Medium-Range Weather Forecasts) enables daily productions of rainfall, soil moisture and snow water equivalent forecasts. For longer lead-time (up to 6 months), two forecast applications are operated every month. The first one uses meteorological forcing from climatology as input, while the second one uses data from a seasonal atmospheric forecast modelling system (Meteo-France System). The use of both climatological and seasonal forecasts makes it possible to know the likely evolution of the hydrological situation and then to adapt water resource management.