| Summary: | Arctic ecosystems play an important role in the functioning of the earth system because they occupy a large area, are sensitive to climate changes and could feedback to affect regional and global climate, Albedo and melt rates measured at a tundra, shrub and forest site at Council (ca 64 54N) and at a tundra site at Ivotuk (ca 68 29N) in Alaska during the snowmelt period in year 2000 showed that the difference in the timing of snowmelt was greater between vegetation types (13 days between shrub and tundra) than between the two sites of different latitude (7days between the two tundra sites with 3.6 difference in latitude). Hence any increase in the abundance and distribution of shrubs and forest could result in earlier spring melt. That the absorption of radiation used for snowmelt was greater for the shrub site than for the other sites was confirmed by degree-index simulations where the shrub site (8.2 mm C۫- 1day-1) required a much larger degree-index than the other sites (forest 3.44 mm C۫-1day-1and 4.1 tundra mm C۫-1day-1) i۫n order to correctly simulate the melt rate. The impacts of changes in snowmelt are not restricted to impacts on surface fluxes but potentially also on hydrological process, regional climate, nutrient and pollutant fluxes. Godkänd; 2005; 20070531 (ysko)
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