Abstract
Abstract. Snow cover is one of the key factors controlling Arctic ecosystem functioning and productivity. In this study we assess the impact of strong variability in snow accumulation during 2 subsequent years (2013–2014) on the land–atmosphere interactions and surface energy exchange in two high-Arctic tundra ecosystems (wet fen and dry heath) in Zackenberg, Northeast Greenland. We observed that record-low snow cover during the winter 2012/2013 resulted in a strong response of the heath ecosystem towards low evaporative capacity and substantial surface heat loss by sensible heat fluxes (H) during the subsequent snowmelt period and growing season. Above-average snow accumulation during the winter 2013/2014 promoted summertime ground heat fluxes (G) and latent heat fluxes (LE) at the cost of H. At the fen ecosystem a more muted response of LE, H and G was observed in response to the variability in snow accumulation. Overall, the differences in flux partitioning and in the length of the snowmelt periods and growing seasons during the 2 years had a strong impact on the total accumulation of the surface energy balance components. We suggest that in a changing climate with higher temperature and more precipitation the surface energy balance of this high-Arctic tundra ecosystem may experience a further increase in the variability of energy accumulation, partitioning and redistribution.
Highlights
The presence or absence of snow has a strong impact on the land–atmosphere interactions and on the exchange of energy and mass
There was no distinct development of a closed snow cover or major events of snow accumulation during the first winter (2012/2013) and by the end of the premelt season as little as 0.09 m of snow pack at the wet fen and 0.14 m at the dry heath was present
In this study we documented the effects of variability in snow accumulation on the surface energy balance of a high-Arctic tundra ecosystem in Northeast Greenland during 2 subsequent years (2013–2014)
Summary
The presence or absence of snow has a strong impact on the land–atmosphere interactions and on the exchange of energy and mass. The influence of the snow on the energy balance is most pronounced during spring when the commonly patchy distribution of snow causes strong spatial variations in surface temperature and surface energy balance components (Chernov, 1988). The meltwater in Arctic soils contributes a considerable proportion of plant-available water during summertime and, as such, end-of-winter snow depth constitutes an important control of the summertime energy partitioning into sensible (H ) and latent heat (LE) fluxes (Langer et al, 2011). Since the end of the Little Ice Age the climate in the Arctic has undergone a substantial warming to the highest temperatures in 400 years (Overpeck et al, 1997). Between the years 1966 and 2003 temperatures in the Arctic increased by 0.4 ◦C per decade with most pronounced warming during the cold seasons (McBean et al, 2005). It is suggested that diminishing sea ice, snow–albedo and ice–albedo feed-
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