HR: 08:30h
AN: C11C-02    [Abstracts]
TI: Is there more snow because it's colder, or is it colder because there's more snow?
AU: * Fletcher, C G
EM: cgf@atmosp.physics.utoronto.ca
AF: Atmospheric Physics Group, University of Toronto, Department of Physics, 60 St. George St, Toronto, ON M5S 1A7 Canada
AU: Kushner, P J
EM: paul.kushner@utoronto.ca
AF: Atmospheric Physics Group, University of Toronto, Department of Physics, 60 St. George St, Toronto, ON M5S 1A7 Canada
AB: Recent observational studies provide strong evidence for lagged relationships between snow cover and subsequent Northern Hemisphere (NH) large-scale winter circulation patterns. However, these analyses typically employ relatively short time series of monthly mean data. This reduces the ability to determine accurately whether the snow forces the atmosphere or vice versa. We present results using observations and coupled GCM output which re-examine how, and to what extent, anomalous snow cover influences the dominant modes of NH winter climate variability. In particular, we focus on the daily atmospheric evolution over Eurasia and above the polar cap before and after extreme autumn and early winter snow events. Anomalous Eurasian snow cover is associated with a short-lived in situ response in tropospheric geopotential height. By contrast, the remote response over the polar cap is longer-lived, nonlinear and coupled to the stratosphere. Dynamical pathways for the persistent, remote response are investigated with idealised and realistic snow scenarios in simulations using an atmospheric GCM.
DE: 0325 Evolution of the atmosphere (1610, 8125)
DE: 0736 Snow (1827, 1863)
SC: Cryosphere [C]
MN: Fall Meeting 2005