#18 Topic: The impact of Arctic climate changes on weather and climate in mid-latitudes
Lecturer: Dörthe Handorf
Date: Monday, May 02, 2022 10:00 – 11:00 a.m.
The recent Arctic Amplification, which started approximately in 1990, have coincided with a period of an increased number of extreme weather and climate events in the Northern Hemisphere mid-latitudes in summer and winter. The increase in extreme events can be partly explained by global warming through thermodynamic arguments, but atmospheric circulation changes might contribute to observed changes in extremes like heat waves or extreme precipitation. In this respect, the hypotheses that Arctic amplification changes might contribute to changes in the characteristics (occurrence, persistence, location) of atmospheric circulation patterns has been widely studied in recent years. Such circulation changes strongly govern changes in cyclones, blockings, and planetary waves which on the other hand can lead to changes in extreme events.
Over the last years, our understanding of Arctic-mid-latitude linkages has been improved by many observational and modeling studies. Although there is consensus within the scientific community that Arctic change can potentially contribute to atmospheric circulation changes in mid-latitudes, and hence, to the occurrence of extreme events, there are controversial discussions, how significant the contribution is and what mechanisms are responsible for these linkages.
Based on observational and modeling studies, the lecture will give an overview about the proposed physical processes and mechanisms that may play important roles in linking Arctic changes to mid-latitude climate and weather. The focus will be on the processes and mechanisms during the winter season, for which most evidence has been found so far. Knowledge gaps and uncertainties leading to divergent conclusions between model and observational studies will be discussed. In addition, a short review of proposed mechanisms for the other seasons will be given. Finally, the outlook will summarize future research directions.