HR: 0800h
AN: GC21A-0145 [Abstracts]
TI: A high-resolution climate model for the United States Pacific Northwest
AU: * Salathe, E P
EM: salathe@washington.edu
AF: University of Washington,
JISAO Climate Impacts Group, Box 354235, Seattle, WA 98195-4235, United States
AU: Mass, C F
EM: cliff@atmos.washington.edu
AF: University of Washington,
Department of Atmospheric Sciences, Box 351640, Seattle, WA 98195-1640, United States
AU: Steed, R
EM: steed@atmos.washington.edu
AF: University of Washington,
Department of Atmospheric Sciences, Box 351640, Seattle, WA 98195-1640, United States
AB:
Simulations of future climate scenarios with a high-resolution climate model show markedly different trends in
temperature and precipitation over the Pacific Northwest than a global model in which it is nested, apparently due
to mesoscale processes not resolved at coarse resolution. Present-day (1990-1999) and future (2020-2029,
2045-2054, and 2090-2099) conditions are simulated at high resolution (15-km grid spacing) using the MM5
model system and forced by ECHAM5 global simulations. Simulations use the IPCC Special Report on
Emissions Scenarios (SRES) A2 emissions scenario. The mesoscale simulations produce regional alterations
in snow cover, cloudiness, and circulation patterns associated with interactions between large-scale climate
change and regional topography and land-water contrasts. These changes substantially alter the temperature
and precipitation trends over the region relative to the global model result or statistical downscaling. Warming is
significantly amplified in regions where snow cover is lost through snow-albedo feedback. Precipitation
increases in autumn are amplified over topography due to changes in the large-scale circulation and its
interaction with the terrain. The robustness of the modeling results is established through comparisons with the
observed and simulated seasonal variability and with statistical downscaling results.
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1637 Regional climate change
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting