THE ROLE OF TURBULENT HEAT FLUXES IN THE ENERGY-BALANCE OF HIGH ALPINE SNOW COVER

Energy balance measurements over a seasonal snow cover were performed near Davos, Switzerland at 2,540 m a.s.l. The energy fluxes were studi ed over dry and melting snow covers. The beginning of snowmelt clearly coincides with the beginning of positive daily sums of net radiation. During snowmelt, net radiation is the dominant energy source. Latent and sensible heat fluxes do not show a significant seasonal change and remain slight over most of the measuring period. This minor contribut ion of the turbulent heat fluxes can be attributed to generally low wi nd speeds in this inner alpine region and to frequent inversions over the melting snow cover. In a changing climate the turbulent heat fluxe s could become increasingly important in the energy balance. Therefore , evaluations of the turbulent heat fluxes from profile measurements a nd the eddy correlation method are compared with simple approximations commonly used in snowmelt models. The conditions under which these ap proximations can be used for routine discharge forecasts are identifie d.