HR: 0800h
AN: C31A-0292    [Abstracts]
TI: Climate Sensitivity to Realistic Solar Heating of Snow and Ice
AU: * Flanner, M
EM: mflanner@uci.edu
AF: University of California-Irvine, Department of Earth System Science University of California, Irvine, Irvine, CA 92697-3100 United States
AU: Zender, C S
EM: zender@uci.edu
AF: University of California-Irvine, Department of Earth System Science University of California, Irvine, Irvine, CA 92697-3100 United States
AB: Snow and ice-covered surfaces are highly reflective and play an integral role in the planetary radiation budget. However, GCMs typically prescribe snow reflection and absorption based on minimal knowledge of snow physical characteristics. We performed climate sensitivity simulations with the NCAR CCSM including a new physically-based multi-layer snow radiative transfer model. The model predicts the effects of vertically resolved heating, absorbing aerosol, and snowpack transparency on snowpack evolution and climate. These processes significantly reduce the model's near-infrared albedo bias over deep snowpacks. While the current CCSM implementation prescribes all solar radiative absorption to occur in the top 2 cm of snow, we estimate that about 65% occurs beneath this level. Accounting for the vertical distribution of snowpack heating and more realistic reflectance significantly alters snowpack depth, surface albedo, and surface air temperature over Northern Hemisphere regions. Implications for the strength of the ice-albedo feedback will be discussed.
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting