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Resolution-Dependent Projections of Extreme Wind Speeds in Canada

Abstract: The effect of anthropogenic climate change on extreme near-surface wind speeds is uncertain. Observed trends are weak and difficult to disentangle from the effects of internal variability, and model projections disagree on the sign and magnitude of trends. Because of their typically coarse spatial resolution, models do not represent important physical phenomena such as surface energy fluxes, extratropical cyclones (ETCs), and upper-level jet streaks as well as their high-resolution counterparts. The variable-resolution configuration of the NCAR Community Earth System Model (VR-CESM) allows us to study the effects of enhanced spatial resolution (7 km) on regional climate change projections of extreme winds, through comparison with standard uniform coarse resolution (110 km) simulations. In this talk, I will explore the added value of regionally refined resolution towards representing extreme wind speed events and their dynamical drivers in a historical context. Then I will show that sign of the climate change response of extreme wind speeds is differs between the coarse and fine resolution simulations and identify different physical mechanisms responsible for the projected changes in each of the simulations. Because the VR-CESM projections are explained by improved representation of local-scale boundary layer processes not resolved at coarse resolution, its results demonstrate the value of enhanced spatial resolution for the study of the effects of climate change on extreme weather.

Event series  Brewer-Wilson Seminar Series