HR: 0800h
AN: C41A-0193    [Abstracts]
TI: Terrestrial and Ecological Impacts of Rain-on-Snow and Melt-Freeze Events in the Circumpolar Arctic
AU: * Rennert, K J
EM: rennert@atmos.washington.edu
AF: University of Washington Atmospheric Sciences, Box 351640, Seattle, WA 98195-1640 United States
AU: Roe, G H
EM: gerard@ess.washington.edu
AF: University of Washington Earth Space Sciences, Box 351310, Seattle, WA 98195-1310 United States
AU: Putkonen, J
EM: putkonen@u.washington.edu
AF: University of Washington Earth Space Sciences, Box 351310, Seattle, WA 98195-1310 United States
AU: Cecilia, B M
EM: bitz@apl.washington.edu
AF: Unversity of Washington Polar Science Center, Box 355640, Seattle, WA 98195-5640 United States
AU: Russell, D E
EM: Don.Russell@ec.gc.ca
AF: Environment Canada Canadian Wildlife Service, 91782 Alaska Hwy., Whitehorse, YK Y1A 5B7 Canada
AU: Wallace, J M
EM: wallace@atmos.washington.edu
AF: University of Washington Atmospheric Sciences, Box 351640, Seattle, WA 98195-1640 United States
AB: Incidents of rain-on-snow and melt-freeze events have been shown to have dramatic impacts on the heat budget of arctic permafrost, frequency of avalanches in mountainous regions, and the health of native caribou and reindeer populations. Latent heat from freezing rainwater that has percolated through the snow pack warms the soil surface, while ice layer formation in the snow pack can lead to snow instability and difficulty of movement and forage for reindeer and caribou populations. These same mechanisms allow melt-freeze events to have similar impacts. To date however, both the relative importance of these two mechanisms, and their extent in the circumpolar Arctic, have yet to be evaluated. We characterize past occurrences of and trends in rain-on-snow and melt-freeze events for the circumpolar arctic using meteorological station data and the European 40-Year Reanalysis, and we place a particular emphasis on the typical synoptic features of these events, and their control by the larger-scale patterns of the atmospheric circulation. We also present analysis of a future climate scenario using daily output from the CCSM3 model under an enhanced greenhouse gas environment which shows an increase in total area with rain-on-snow events, as well as an increase in the frequency of rain on snow and melt freeze events for much of the high northern latitudes. We use each of these characterizations as inputs to a permafrost and snow pack model to quantify the past and future terrestrial and ecological impacts of these events in the circumpolar arctic.
DE: 1803 Anthropogenic effects
DE: 1854 Precipitation (3354)
DE: 1863 Snow and ice (1827)
DE: 1630 Impact phenomena
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting