Challenges in Simulating the Influence of Arctic Amplification on Midlatitude Extreme Weather

Observational and modeling studies that employ global climate models mostly diverge on the influence of Arctic amplification in general and sea ice melt in particular on extreme winter weather across the mid-latitudes. The most common response to resolve the discrepancy is to argue that recent observed extreme winter weather is a product of internal atmospheric or natural variability and not related to Arctic change. However standardized and coordinated modeling experiments may not be sufficient to overcome likely model deficiencies to accurately assess the influence of Arctic sea ice on mid-latitude weather and climate variability. I will show using examples from the past two winters how the models missed large scale atmospheric variability associated with large polar vortex disruptions. And if appropriate, I will also discuss in the context of winter 2019/20. I will also show model deficiencies in simulating the atmospheric response to polar vortex disruptions from analysis of CMIP5 data. Many observational studies argue that Arctic influence on mid-latitude weather is through the polar vortex. Correct representation of polar vortex variability and the atmospheric response is critical for the correct interpretation of model experiments on the possible influence of Arctic amplification/sea ice loss on mid-latitude weather extreme weather.