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 opportunity for the evaluation of hydrological models, since model process representations can be compared with observations. The distributed hydrology-soil-vegetation model (DHSVM) was used to simulate the latent 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 tower in the northern study area during the summer of 1994. The model did a reasonable job of simulating both the seasonal average fluxes and the diurnal cycle of the surface heat fluxes. However, a lag was observed in the simulation of the sensible heat flux, which was attributed to an inadequate representation of the ground heat flux and ground heat storage. It was also noted that direct soil evaporation forms an important part of the latent heat flux simulated by the model. Incorporation of a more complete soil thermal model, and further field work in 1996 to evaluate the importance of the moss layer and the direct evaporation from the soil, is expected to lead to further improvements.