Interactions between atmosphere and land surface in the ECMWF model

Anton Beljaars, European Centre for Medium-Range Weather Forecasts (ECMWF)

Abstract for Special Seminar on Monday, October 3, 2016 at 3 pm in PAS 220

An overview will be given of the role of land/atmosphere interaction in the ECMWF forecasting system, with focus on moisture and heat exchange.

Water vapour budgets of the atmosphere and land surface are tightly coupled in summer with a strong feedback between evaporation and precipitation.  Runoff is believed to be a key process in the drying of the coupled system in spring and early summer. To exploit predictability in the monthly and seasonal range it will be necessary to improve the representation of runoff in land surface models, which requires a close collaboration between meteorologists and hydrologists.

 Realistic thermal coupling between land surface and atmosphere is crucial for the simulation of near surface temperate over land. Night time cooling is particularly sensitive to the representation of turbulent diffusion, vegetation/land use, soil properties and snow. Detailed field observations for various land use types are necessary to constrain the relative importance of different processes and to avoid compensating errors.