Towards High-Resolution Climate Projections for the Great Lakes Region

The next step in the Ensemble project is developing and testing an advanced regional climate model for the GL region using a high spatial resolution to represent complex circulations. Earlier phases of regional
climate modeling demonstrated the need for higher spatial resolution to capture hydrological extremes, including lakeeffect snowstorms, and more advanced lake modeling for the GL beyond the use of a 1D lake model to accurately capture the evolution of lake temperatures, ice cover, and fluxes of heat and moisture to the atmosphere. GLISA’s assessment of enhanced resolution global climate models resulted in the conclusion that accurate representation of lake-effect snowfall requires more sophisticated treatments of the lakes themselves. As a result of both findings, the UW team completed the coupling of a 3-km regional climate model to a 3D lake model over the last year that is capable of capturing the advanced dynamics of lake circulation and its impact on lake temperature, lake ice formation and its motion, lake-atmosphere interactions, and resulting lake-effect snowstorms. The team assessed the credibility, strengths, and weaknesses of the HighResMIP high-resolution global climate models during the cold season to provide guidance to stakeholders in terms of their reliability and usability. GLISA evaluated the
model performance of the NASA Unified Weather Research and Forecasting model (NU-WRF) in its current version for the GL region and the 2014/15 cold season. Several model deficiencies were identified, including a cold bias both in  the atmosphere and in the 1D lake, excessive precipitation and lake ice cover, and insufficient evaporation over Lakes Superior and Huron (Notaro et al. 2021). These findings will guide the ongoing efforts coupling NU-WRF to the Finite Volume Community Ocean Model (FVCOM; a 3D lake
model) in support of the next generation of regional climate models for the GL basin.