Evaluation of land surface processes in the IFS

Major upgrades have been implemented over the last few years in the soil hydrology, snow
and vegetation components of the ECMWF land surface parametrization. Compared to the
scheme used in ERA-Interim and ERA-40 reanalyses, the current model has an improved
match to soil moisture and snow field-site observations with a beneficial impact on the
forecasts of surface energy and water fluxes and near-surface temperature and humidity. This
is verified by conventional synoptic observations and by dedicated flux-tower sites for
forecasts ranging from daily to seasonal. The gain in hydrological consistency is also of
crucial importance for the data assimilation of land surface satellite observations in water
sensitive channels. The scheme described here, currently used for daily medium-range
forecasts, will be adopted by the new Seasonal Forecasting System and included in future
reanalyses.