Mesoscale Surprises in Complex Terrain Revealed by Regional Climate Simulations

Global climate models have inadequate resolution for the simulation of regional meteorological phenomena driven by terrain and land-water contrasts. Could the interactions of terrain and coastal contrasts with changing synoptic scale flow associated with global warming produce significant modifications to global model predictions of expected impacts? Will mesoscale model’s reveal regional surprises associated with global warming? Do these effects suggest the importance of dynamical downscaling over statistical approaches?

This presentation will examine this question over the Pacific Northwest, making use of the output of high-resolution dynamically downscaled modeling simulations for the next century. It will be shown that deamplifying upper level disturbances associated with global warming, will result in weakened downsloping easterly flow on the Cascades and Rockies, lessening the enhanced warm extremes produced by the general warming of the planet. Localized warming will occur during the spring as melting snow on the slopes of regional terrain allows greater absorption of solar insolation. And enhanced warming inland in the presence of the Pacific coast may produce enhanced onshore flow, cooling, and low clouds later in the century.