Cold air outbreaks (CAOs) in the mid-latitudes of the Northern Hemisphere are the most frequently occurring extreme events with large impact areas in boreal winter, posing a great threat to human life and the socioeconomic wellbeing of modern society. However, the predictability of the occurrence of individual CAO events is constrained by the two-week predictability limit of numerical weather predictions. In our recent studies, we have found that CAOs over the two major continents in the Northern Hemisphere on average tend to take place within a short time period from 1 week before to 1 to 2 weeks after anomalously strong mass transport into the polar stratosphere, which is coupled with the anomalous equatorward mass transport of cold polar air near surface by planetary waves with deep structure.
Dr. Yueyue Yu is an assistant professor at the Institute of Atmospheric Sciences, Nanjing University of Information Sciences and Technology. She received her PhD in Meteorology from the Institute of Atmospheric Physics, Chinese Academy of Sciences, in 2015. Her research interests center around the dynamics of the global mass circulation and its association with climate variability and climate change, including relationships between the global mass circulation and the mechanisms and predictability of cold-air outbreaks in mid-latitudes. She has been a lead researcher on the cold air outbreak sub-seasonal forecast team at Florida State University since September 2014.