HR: 1340h
AN: A53B-0892    [Abstracts]
TI: Snow cover's influence on North American ground temperatures, 1950-2000
AU: * Bartlett, M G
EM: bartlett@mines.utah.edu
AF: Department of Geology and Geophysics University of Utah, 135 South 1460 East WBB 719, Salt Lake City, UT 84112 United States
AU: Chapman, D S
EM: dchapman@park.admin.utah.edu
AF: Department of Geology and Geophysics University of Utah, 135 South 1460 East WBB 719, Salt Lake City, UT 84112 United States
AU: Harris, R N
EM: rnharris@mines.utah.edu
AF: Department of Geology and Geophysics University of Utah, 135 South 1460 East WBB 719, Salt Lake City, UT 84112 United States
AB: Borehole-based climate reconstructions suggest that the Northern Hemisphere warming has been about 1.2 K over the past 500 years while proxy methods indicate warming closer to 0.7 K. One suggested reconciliation of borehole and proxy reconstructions is that long-term variations in seasonal snow cover may influence the borehole record. We have developed a snow-ground thermal model that predicts transient warming or cooling of the annual mean surface ground temperature as a function of variations in surface air temperature and snow seasonality. The model is verified using meteorological and ground temperature observations from North America. Inter-annual correlation coefficients of observed and modeled ground temperatures from this dataset range from 0.81 to 0.99, demonstrating that the model is capable of detecting trends ground temperatures in the presence of snow. We compute the regional response of surface ground temperatures to changes in seasonal snow cover in North America from 1950-2000. Snow and air temperature data used in the modeling come from the United States Historical Climatology Network, the Canadian Daily Climatic Dataset, and a set of National Weather Service Co-Op stations in Alaska. Model results suggest snow cover has inhibited 0.2 K of the 0.5 K change in winter surface air temperature warming in the region over the past 50 years from entering the ground temperature record. Variations in snow event seasonality (onset and duration) have led to less than 0.05 K of net change in surface ground temperatures in North America during this period.
DE: 1863 Snow and ice (1827)
DE: 1620 Climate dynamics (3309)
DE: 1645 Solid Earth
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting