During snowmelt over a continuous snow cover, the vertical turbulent
exchanges of sensible and latent energy are influenced by regional air-mass
characteristics, which exert a strong control on air temperature. In
high-latitude sites, the melting surface rapidly becomes heterogeneous, with
patches of snow and snow-free areas. Local advection occurs when
near-surface air layers are warmed due to sensible heal flux from the
snow-free areas, with the resulting heat transferred horizontally to
adjacent snowpatches. This advection greatly increases the rate of snowmelt
along the leading edges of the snowpatches. In order to estimate correctly
the average melt rates of the snowpatches and the bulk energy balance of the
entire landscape, it is necessary to estimate the local advection component.
To date, few studies have dealt with this problem. This paper reports
results from an Arctic tundra site located approximately 55 km northeast of
Inuvik, Northwest Territories, Canada. The importance of local advection is
estimated by comparing the sensible heat flux of the snowpatches to
estimates of sensible heat without local advection. This latter term is
derived from a relationship between upper air temperature and sensible heat
flux over a continuous snow cover. This work has important implications for
developing models that correctly represent the cryosphere of tundra regions,
and in developing appropriate scaling techniques for heterogeneous
landscapes.