Talks and presentations

See a map of all the places I've given a talk!

Downward Migration in the Zonal Mean Circulation of the Tropical Atmosphere

January 31, 2020

Seminar, University of Washington, Department of Atmospheric Science, Seattle WA

This is my first ever virtual colloquium visit. From the comforts of my own office, I’ll present my talk over the internet, coupled with a day of virtual meetings with students, postdocs, and faculty. The goal is to reduce our CO2 footprint – something our field should mindful of more than any other – but it will also help reduce the “family footprint”, i.e. the impact on spouses left to deal with kids who tend to get sick this time of year. Ugh. Only catch is that the seminar is 3:30 pm on a Friday, Pacific time!

Downward migration of the zonal-mean circulation in the tropical atmosphere

December 11, 2019

Invited Talk, AGU Fall Meeting, San Francisco California

The annular modes of the extratropical atmosphere have received much attention for quantifying and predicting variability of the jet streams and storm tracks, despite the limited zonal coherence of midlatitude variability. In the tropics, annular Huctuations of the circulation have not been investigated, despite the comparative dominance of zonal-mean variations in this region, associated with weak temperature gradients at low latitudes.

Trace Gas Transport in the Stratosphere: Opportunities and Challenges

November 19, 2019

Invited Talk, ECMWF Workshop on Stratospheric predictability and Impact on the Troposphere, Reading, UK

The transport of trace gases through the stratosphere impacts surface climate. Small changes in stratospheric water vapor, on the order of one part per million, can impact surface temperature by as much as a tenth of a degree. A sudden drop in stratospheric water vapor of this magnitude – a response to internal variability of the atmosphere – was observed in 2000. Chemistry climate model simulations of stratospheric ozone also depend critically on the transport of ozone and ozone depleting substances, and biases in transport are a leading source of uncertainty in the recovery of stratospheric ozone. Volcanic aerosols (and the possibility of injecting sulfur into the stratosphere for climate intervention) provides another example of the importance of stratospheric tracer transport for the climate at the surface.