Comparative surface energy budgets in western and central subarctic regions of Canada

Abstract

The surface energy balance was measured over two summer seasons (1996 and 1997) at three Canadian subarctic sites. These were a wetland site in the central subarctic and a wetland and dryland site in the western subarctic. These sites have similar temperature regimes but the central subarctic site receives twice as much rainfall as each of the western sites. The sites display substantial differences in their surface characteristics. A comparison between the three study sites allows definition of the impact of surface controls on the surface energy budget, for the two subarctic locations. By comparing the evaporation rates between these three sites the surface control mechanisms at the local scale (i.e. microtopography, vegetation cover and organic layer thickness) can be examined relative to the larger scale geographical factors. The two wetland sites demonstrated similar evaporation behaviour but the dryland evaporates substantially less. This similarity in wetland evaporation in spite of major differences in rainfall and standing water demonstrates the importance of the surface organic layer in transporting and storing water for evaporation. The magnitude of convective and conductive heat fluxes is strongly correlated with temperature in both regions. Warm temperatures enhance the latent and ground heat fluxes while suppressing the sensible heat flux at all sites. Cold temperatures have the opposite effect. Copyright © 2000 Royal Meteorological Society