[SLS] Rachel Wu (Columbia)

“Subseasonal Prediction of the Stratospheric Polar Vortex: Skill, Uncertainty, and their Dynamical Origins”

Wintertime variability of the stratospheric polar vortex (SPV) is strongly influenced by upward-propagating planetary waves, which break in the stratosphere and deposit momentum, thereby weakening the vortex. Because SPV variability can affect surface weather, it provides a potential source of predictability on subseasonal timescales.
In this talk, I first assess how skilfully SPV variability is predicted by the ECMWF subseasonal prediction system. I then show how uncertainty in SPV predictions depends on the SPV state at forecast initialization. Finally, I use the 2018 sudden stratospheric warming as a case study to show how large forecast uncertainty can originate from known teleconnection pathways — propagating from the tropical troposphere, into the extratropics, and ultimately into the stratosphere.

Sack Lunch Seminar Series —
Informal seminar series within PAOC (Program in Atmospheres, Oceans, and Climate) that focuses on more specialized topics than the PAOC Colloquium. The presentations are either given by an invited speaker or by a member of PAOC and can focus on new research or discussion of a paper of particular interest.

Contact: sacklunch-committee@mit.edu