Skip to Content

Everything you wanted to know about the polar vortex but were too afraid to ask

Millions of people across eastern North America spent the winters of 2013/14 and 2014/15 being plagued by both cold weather and a dramatic overuse of the phrase “polar vortex.” In the past this phrase was used to refer to the winds in the polar stratosphere, but during those recent winters it came to be applied—largely by the media—to the tropospheric jet stream as well. Although these stratospheric and tropospheric polar vortices usually behave independently, at times there is a strong coupling between them. In this talk, I will show how my own research has been useful in better understanding the drivers of variability of both of these types of polar vortex. I will describe a novel statistical decomposition of atmospheric disturbances into standing and travelling waves that I have developed, and I will apply it to better understand two mechanisms in the atmosphere: first, the forcing of sudden stratospheric warmings (which are breakdowns in the stratospheric polar vortex) and second, the occurrence of cold temperature extremes in central and eastern North America (the popular use of “polar vortex”). Using the spectral method described above, I will show that standing waves are instrumental for both of these phenomena.