Blocking and General Circulation in GFDL Comprehensive Climate Models

Abstract This study examines the climatology and dynamics of atmospheric blocking, general circulation features that influence blocks in GFDL’s atmosphere-only (AM4) coupled atmosphere–ocean (CM4) comprehensive models. We compare AM4 CM4 with reanalysis, focusing on winter Northern Hemisphere. Both models generate correct blocking planetary-scale signatures stationary wave. However, at regional scales some biases exist. In eastern Pacific over western North America, both excessive frequency too strong a Atlantic, little weakened A block-centered compositing analysis block-onset reveals 1) produce realistic patterns high-frequency (1–6-day) eddy forcing 2) capture notable differences 500-hPa geopotential height field between Atlantic blocking. fail to reproduce stronger wave activity flux convergence compared Pacific. Overall, terms location, frequency, duration, area are quite similar despite having large sea surface temperatures climatological zonal circulation. could suggest other factors be more dominant generating for these GCMs. Significance Statement Atmospheric persistent high pressure systems can lead hazardous weather. Historically, climate have had trouble capturing blocks, but recent changes might improvements. As such, work herein investigates spatial distribution, prevalence, size, wintertime NOAA long-term-average pattern properly key dynamical features. much United States, northern Ocean Europe. These consistent waves biases, not jet stream bias. downplays role being responsible biases.