[Seminar] Prof. Baek-Min Kim

How do intermittency and simultaneous processes obfuscate the Arctic influence on midlatitude winter extreme weather events?

Pronounced changes in the Arctic environment add a new potential driver of anomalous weather patterns in midlatitudes that affect billions of people. Recent studies of these Arctic/midlatitude weather linkages, however, state inconsistent conclusions. A source of uncertainty arises from the chaotic nature of the atmosphere. Thermodynamic forcing by a rapidly warming Arctic contributes to weather events through changing surface heat fluxes and large-scale temperature and pressure gradients. But internal shifts in atmospheric dynamics — the variability of the location, strength, and character of the jet stream, blocking, and stratospheric polar vortex (SPV) — obscure the direct causes and effects of linkages. It is important to understand these associated processes to help differentiate Arctic-forced variability from natural variability. Though complicated by intermittency and obfuscated by large natural variability in the extratropics, observational evidence for Arctic/midlatitude weather linkages continues to accumulate, along with understanding of connections with pre-existing climate states. Relative to natural atmospheric variability, sea-ice loss has so far played only a secondary role in Arctic/midlatitude weather linkages.