HR: 0800h
AN: C21A-1071 INVITED     [Abstracts]
TI: Snowmelt in an Arctic Mountain Shrub Tundra
AU: * Pomeroy, J W
EM: pomeroy@usask.ca
AF: University of Saskatchewan, Centre for Hydrology, 117 Science Place, Saskatoon, SK S7N 5C8 Canada
AU: Bewley, D S
EM: ddb97@aber.ac.uk
AF: University of Wales - Aberystwyth, Centre for Glaciology, Institute of Geography and Earth Sciences, Aberystwyth, SY23 3DB United Kingdom
AU: Essery, R L
EM: rie@aber.ac.uk
AF: University of Wales - Aberystwyth, Centre for Glaciology, Institute of Geography and Earth Sciences, Aberystwyth, SY23 3DB United Kingdom
AU: Granger, R J
EM: raoul.granger@ec.gc.ca
AF: National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK S7N 3H5 Canada
AU: Link, T
EM: tlink@uidaho.edu
AF: University of Idaho, Dept. of Forest Resources, Moscow, ID 83844-1133 United States
AU: Marks, D
EM: danny@nwrc.ars.usda.gov
AF: USDA, Northwest Watershed Research Center, 800 Park Blvd., Suite 105, Boise, ID 83712-7716 United States
AB: Observations of radiation, turbulent energy and phase change were made over melting snow in a mountain shrub tundra environment. Valley bottoms are covered by tall shrubs whilst hillslopes sustain short shrubs and plateaux and ridges only sparse shrub tundra. Snow accumulation was found to be higher in the shrubs than in open tundra due to retention of snowfall by shorter shrubs and redistribution of blowing snow to taller shrubs; topographic effects on wind speed and snow erosion were magnified by greater vegetation roughness in more sheltered sites. Shrubs that were buried by winter snow accumulation were observed to spring up during melt, rapidly altering the surface energy balance, primarily by lowering the albedo. The albedo of exposed dense shrubs over snow was substantially lower than over open snow. As a result, net radiation over exposed shrubs was much higher than that over open snow; however net radiation to snow under shrub canopies was similar to that to open snow. Despite substantial differences in the near snow surface wind speeds, the latent heat flux from snow under shrubs did not differ substantially from that from open snow. However, sensible heat fluxes from the surface increased due to the presence of 'warm' shrubs over 'cold' snow (i.e. warmer or colder than air temperature), particularly on clear days. Both upward sensible heat flow from shrub to atmosphere and a downward component that contributes to snowmelt were detected. As a result, snowmelt rates were generally, but not always, slightly enhanced under shrub canopies in comparison to open snow.
DE: 0718 Tundra (9315)
DE: 0736 Snow (1827, 1863)
DE: 0740 Snowmelt
DE: 1840 Hydrometeorology
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
SC: Cryosphere [C]
MN: Fall Meeting 2005