How Well Does the Climate Model Simulate the North Pacific Blocking Dynamics?

Abstract The dynamics of North Pacific (NP) winter blocking and its representation in climate models are investigated by calculating the quasi‐geostrophic geopotential tendency budget. The budget analysis reveals that NP blocking develops mainly through the quasi‐barotropic process, which reinforces the NP ridge from the lower troposphere to the upper troposphere by low‐frequency vorticity fluxes. Although relatively minor, high‐frequency eddies and their interactions with low‐frequency eddies also support the barotropic development of NP blocking. Additionally, the development of NP blocking is enhanced by both baroclinic and diabatic processes. While the former deepens the upstream trough in the lower troposphere, the latter induces the divergent outflows in the upper troposphere. These processes are well captured by the models, although the models overestimate NP blocking frequency an…