HR: 1340h
AN: A53A-0866    [Abstracts]
TI: High-Resolution Regional Climate Model for the Pacific Northwest
AU: * Salathe, E P
EM: salathe@washington.edu
AF: University of Washington, Box 423542, Seattle, WA 98195-4235 United States
AU: Mass, C
EM: cliff@atmos.washington.edu
AF: University of Washington, Box 423542, Seattle, WA 98195-4235 United States
AU: Zahn, P
EM: patrick@atmos.washington.edu
AF: University of Washington, Box 423542, Seattle, WA 98195-4235 United States
AU: Steed, R
EM: steed@atmos.washington.edu
AF: University of Washington, Box 423542, Seattle, WA 98195-4235 United States
AB: We have developed a high-resolution climate model of the Pacific Northwest based upon the MM5 mesoscale weather model and performed downscaling simulations forced by output from the National Center for Atmospheric Research-Department of Energy Parallel Climate Model (PCM). Decade-long simulations will be presented for present-day climate and for a future climate-change scenario. Results from these simulations are used in assessing the impacts of climate change on hydrology and air quality. To match the climate model grid spacing of approximately 300 km, we use 135, 45, and 15 km grids in MM5. The outer grid covers much of the Northeast Pacific and North America to encompass large-scale processes critical to Pacific Northwest climate. The intermediate grid encompasses the conterminous United States. The inner grid covers the states of Washington, Oregon, and Idaho. Initial and boundary conditions as well as interior nudging for MM5 runs are taken from the global climate model simulations. To perform long runs while maintaining stability and mass conservation of the simulation, we employ nudging (Newtonian relaxation) of the outer nest toward the global climate model simulation, thus the 135-km nest is constrained tightly to the global model simulation and yields a smooth transition from the global model to MM5. With this technique, we can run MM5 continuously for long periods, without periodic restarts. Nudging also preserves the large-scale state provided by the global model. Thus, the downscaling provides the regional meteorological details consistent with that large-scale state, which is assumed to be well resolved by the global model. The interaction of land-surface processes and mesoscale meteorological processes is a critical issue in regional climate modeling. We consider several issues and methods for initializing the land surface properties and applying a land-surface model. We discuss the advantages of performing a single continuous multi-year run versus several one-year runs in the context of the Pacific Northwest climate.
UR: http://www.atmos.washington.edu/$\sim$salathe/reg\_climate\_mod/
DE: 3322 Land/atmosphere interactions
DE: 3329 Mesoscale meteorology
DE: 3309 Climatology (1620)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting