Speaker's Website: http://www.eps.jhu.edu/~cig4/

Host: Aditi Sheshadri / Tim Cronin

Title: Coupling between Tropical Tropospheric and Polar Stratospheric Variability

Abstract: Tropical tropospheric variability can influence the wintertime extratropical stratosphere. Specifically, certain phases of the Madden-Julian Oscillation (MJO) and El Nino leads to a weakened stratospheric polar vortex. The mechanism linking tropical tropospheric variability to polar stratospheric appears to be common to both El Nino and the MJO. The deepening of the wintertime Aleutian low, as occurs e.g. during El Nino events, leads to an intensification of the tropospheric climatological planetary wave pattern. This increase in tropospheric planetary waves leads to increased wave driving of the wintertime polar vortex, so that the net effect is a weakened vortex. Once the vortex is weakened, the anomalies propagate downwards into the troposphere and lead to the negative phase of the Northern Annular Mode.

Faculty Host: Alan Plumb