Regional estimates of heat and evaporation fluxes over non-homogeneous terrain. Examples from the HAPEX-MOBILHY programme

Questions related to the spatial integration of turbulent surface fluxes of heat and moisture up to horizontal scales of 100km are discussed. Results taken from the HAPEX-MOBILHY programme are presented, concerning either comparisons between surface-based and aircraft measurements, or estimates derived from numerical simulations of the large-scale hydrological balance, or finally area-averaged values obtained from atmospheric numerical mesoscale models. Conclusions are drawn from these results on how to estimate spatially-averaged surface fluxes efficiently.