POINT EVALUATION OF A SURFACE HYDROLOGY MODEL FOR BOREAS

Detailed observations of moisture and energy fluxes made at the Boreal Ecosystem-Atmosphere Study (BOREAS) tower flux sites offer a unique o pportunity for the evaluation of hydrological models, since model proc ess representations can be compared with observations. The distributed hydrology-soil-vegetation model (DHSVM) was used to simulate the late nt and sensible heat fluxes at the old black spruce and old jack pine tower flux sites in the southern study area and the old black spruce t ower in the northern study area during the summer of 1994. The model d id a reasonable job of simulating both the seasonal average fluxes and the diurnal cycle of the surface heat fluxes. However, a lag was obse rved in the simulation of the sensible heat flux, which was attributed to an inadequate representation of the ground heat flux and ground he at storage. It was also noted that direct soil evaporation forms an im portant part of the latent heat flux simulated by the model. Incorpora tion of a more complete soil thermal model, and further field work in 1996 to evaluate the importance of the moss layer and the direct evapo ration from the soil, is expected to lead to further improvements.