Peterson, Kenneth S听1听;听Steger, Andrew R听2听;听Perrot, Danielle O听3听;听Pugh, Evan T听4听;听Deems, Jeff S听5听;听Molotch, Noah P听6听;听Small, Eric E听7
1听University of Colorado, 麻豆影院
2听University of Colorado, 麻豆影院
3听University of Colorado, 麻豆影院
4听University of Colorado, 麻豆影院
5听University of Colorado, 麻豆影院
6听University of Colorado, 麻豆影院
7听University of Colorado, 麻豆影院
Contaminants from bark beetle-infested trees (litter) and aeolian deposition (dust) perturb the snowpack surface albedo in subalpine forested environments. These contaminants have separately been shown to significantly increase snowmelt timing by as much as three weeks. Here, we are examining the relative and combined radiative effects of dust and needle contaminants at the snow surface by measuring snow surface albedo. Additionally, we are investigating effects on energy transfer within the snowpack. From field experiments involving applications of various concentrations and combinations of dust and needle contaminants, we find that needles have a greater influence on snow surface albedo reduction; application of needles resulted in an albedo reduction of 0.0146 per percent increase in contaminant cover, whereas dust application resulted in an albedo reduction of 0.0061 per percent increase in contaminant cover. Needle application to a dusty snow surface resulted in 0.0043 albedo reduction per percent contaminant cover, and dust application to a snow surface with needles already present resulted in 0.0036 albedo reduction per percent contaminant cover.
However, snow albedo naturally decreases as a function of snow age and grain size. By making daily snow albedo measurements on plots with and without the presence of contaminants for seven consecutive days, our current experiments aim to control for the albedo effects of snow age. Additionally, because dust and needle-litter have important radiative effects at the snow surface, we are interested in how these contaminants may affect energy transfer when buried within the snowpack. To observe this, we will make weekly snow pit observations of the vertical distribution of temperature, density, snow grain size, and snow layers in plots containing known amounts of dust and litter. Ultimately, albedo will become a more significant factor in snowmelt processes in the more-open canopy conditions associated with tree death. Therefore, our understanding of surface albedo will become increasingly important in snow-covered areas affected by both beetle-induced tree mortality and aeolian dust deposition.
Painter T H, Deems J S, Belnap J, Hamlet A F, Landry C C and Udall B 2010 Response of Colorado River runoff to dust radiative forcing in snow Proc. Natl. Acad. Sci. USA 107 17125-30
Pugh E, Small E, 2011 The impact of pine beetle infestation on snow accumulation and melt in the headwaters of the Colorado River. Ecohydrology 10.1002/eco.239