HR: 0800h
AN: C21A-1074    [Abstracts]
TI: Influence of Aspect on Snowmelt Irradiation on Forested Mountain Slopes
AU: * Ellis, C R
EM: cre152@mail.usask.ca
AF: University of Saskatchewan, 117 Science Place, Saskatoon, Sk S7N 5C8 Canada
AU: Pomeroy, J W
EM: pomeroy@usask.ca
AF: University of Saskatchewan, 117 Science Place, Saskatoon, Sk S7N 5C8 Canada
AB: It is well known that snowmelt energy from radiation varies due to the effects of topography and vegetation cover. However it is not well understood how the combination of topography and vegetation influences sub-canopy radiation fluxes to snow. To investigate, three natural lodgepole pine (Pinus contorta) stands in the Rocky Mountains of Marmot Creek Research Basin, Alberta, Canada were instrumented with radiometers. Radiation was observed at an open reference and beneath forests on north (20§ slope; 351§ azimuth) and southeast (19§ slope; 126§ azimuth) aspects with a level site serving as a control. Due to the presence of canopy gaps on the southeast slope, radiometers were placed in open, medium and dense parts of the stand. The pine forest exhibited variations in cover having mean tree densities of 1.83, 2.05 and 2.52 trees m^-2 at southeast, level and north slopes. Both short-wave and long-wave incoming radiation fluxes were measured in sites with complete snow cover and experiencing melt. Ratios of sub-canopy short-wave irradiance to open-level site mean irradiance of 12.81 MJ m^-2 d^-1 were 0.38, 0.21 and 0.08 for southeast slope, level, and north slope forest sites, respectively. Sub-canopy long-wave irradiance ratios relative to the average open-level site irradiance of 9.61 MJ m^-2 d^-1 were 2.82, 2.82 and 2.87 respectively for southeast slope, level and north slope forest sites. Sub-canopy net radiation ratios relative to a mean net radiation of 3.2 MJ m^-2 d^-1 at the open-level site were 0.33, 0.09 and 0.07 for southeast, level and north slope forest sites. Lower north slope receipts of sub-canopy short-wave were found to be offset by an increased sub-canopy long-wave flux.
DE: 1827 Glaciology (0736, 0776, 1863)
DE: 1863 Snow and ice (0736, 0738, 0776, 1827)
SC: Cryosphere [C]
MN: Fall Meeting 2005