Are HighResMIP Global Climate Models Capable of Reasonably Capturing Lake-Effect Snow in the Laurentian Great Lakes Basin?

Abstract:

The Great Lakes have vast socio-economic importance, containing 95% of the United States’ freshwater supply and impacting power production, navigation, industry, commerce, recreation, agriculture, and ecosystems. Their basin has been a regional hotspot of pronounced climate change impacts, including rising air and water temperatures, more frequent heavy precipitation events, declining lake ice cover, enhanced lake evaporation, and increases in lake-effect snowfall. Reports by the Intergovernmental Panel on Climate Change and the National Climate Assessment have provided critical summaries of existing research on ongoing and projected changes in the mean climate and extremes, yet they have given minimal attention to lake-effect snowstorms, for which future trends are poorly known. The insufficient investigation is largely due to a general lack of suitable modeling tools that properly represent the Great Lakes and associated lake-atmosphere interactions, at a sufficient spatial scale. The High Resolution Model Intercomparison Project (HighResMIP) offers an unprecedented opportunity to assess the capability of high-resolution global climate models (GCMs) to accurately represent lake-atmosphere interactions and resulting lake-effect snowstorms. In response, the current project focuses on developing a process-oriented assessment of the HighResMIP models in terms of their representation of lake-atmosphere interactions and lake-effect snowfall in the Great Lakes Basin. The HighResMIP GCMs are characterized by a spectrum of methods for representing the lakes, including prescribed lake-surface temperatures and ice cover, ocean grid cells, and 1D lake models. Among the HighResMIP models, higher spatial resolution facilitates the capacity to simulate the region’s distinct lake-effect zones and topographic influences, but does not always guarantee improved snowfall simulations and often leads to reduced climatological snowfall. Most of the GCMs, especially those applying 1D lake models, produce insufficient annual snowfall, in particular downwind of Lake Superior. Likewise, they often generate too early of a seasonal peak in lake-effect snowfall downwind of Superior.