Patterns of dust-enhanced absorbed energy and shifts in melt timing for snow of southwestern Colorado
Date
2020
Authors
Duncan, Caroline R., author
Fassnacht, Steven, advisor
Kampf, Stephanie, committee member
Ham, Jay, committee member
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Abstract
Deposited dust layers reduce the surface albedo of snow and accelerate melt by this change to the snowpack energy balance. Senator Beck Study Basin in the San Juan Mountains of southwestern Colorado monitors the effects of dust on midlatitude continental snowpack. Continuous automated measurements include shortwave and longwave radiation in addition to conventional micrometeorological variables. Dust layer characteristics and snow properties are collected during snow pit excavation throughout each ablation period. Both sets of data were used to simulate snowpack under observed and dust-free conditions with the snow energy balance model SNOBAL for WY2007 to WY2019. Across the 13 years, dust concentrations ranged from 0.16 to 4.80 mg g-1 resulting in a range of daily mean dust-enhanced absorbed visible energy from 31 to 50 W m-2 during ablation, with hourly peaks up to 347 W m-2. We found snow melt accelerated by 11 to 31 days in a logarithmic response to end-of-year dust concentration modified by seasonal variations in snow amount and cloud cover.
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Subject
melt
dust
snow