Influences of atmospheric blocking on North American summer heatwaves in a changing climate: a comparison of two Canadian Earth system model large ensembles

Abstract As summer heatwaves have severe adverse impacts on human society and ecosystems, there is need to better understand their meteorological drivers future projections under climate change. This study investigates the linkage between atmospheric blocking (June–August) over North America using two reanalysis datasets (ERA-Interim NCEP-DOE-R2) large-ensembles of Canadian Earth System Models (CanESM2 CanESM5) for 1981–2010 baseline period as well projected changes high-emission scenarios out 2071–2100. Compared NCEP-DOE-R2, both ensembles underestimate frequency in north Pacific, Alaska, western Canada (by − 37%), while CanESM2 ensemble also underestimates central eastern 36%). CanESM5 generally shows performance than its reproduction Canada, which consistent with overall improvements simulating large-scale patterns. The ensembles, however, agree reanalyses blocking-heatwave linkages. Above-normal heatwave occurs core surroundings due positive heat flux anomalies, below-normal at remote locations and/or southern flanks cold air temperature advection anomalies. Future differ models, largely significant under-representation by CanESM2. However, project similar behavior spatial distributions linkages, indicating will continue play an important role development future.