Submitted to: Trans American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 11/7/2005
Publication Date: 12/15/2005
Citation: Pomeroy, J.W., Bewley, D.S., Essery, R.L., Granger, R.J., Link, T., and Marks, D. 2005. Snowmelt in an arctic mountain shrub tundra, abstract C21A-1071, Invited Poster, Eos, Transactions of the American Geophysical Union, 86(52):F432
Technical Abstract: Observati0ons 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 the open tundra due to retention of snowfall by 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 late3nt 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.