Start
September 11, 2020 - 3:00 pm
End
September 11, 2020 - 4:00 pm
Categories
Convective Meteorology (Mesoscale Dynamics)Convective Meteorology (Mesoscale Dynamics) Seminar
When the atmosphere yells “Pull!”: A 22-year Evaluation of Convection Reaching the Stratosphere over the United States
Dr. Cameron Homeyer
Friday, September 11th
3:00 pm
Join Google Meet:
https://meet.google.com/ksh-txvg-kni
Storms that reach and overshoot the tropopause are often severe, are responsible for delivering water to the stratosphere and exchanging additional greenhouse gasses between the troposphere and stratosphere, and help drive the large scale circulation of the stratosphere via gravity wave generation. Most efforts focused on overshooting convection have been directed toward storms that reach above the coincident lapse-rate tropopause. However, convection has also been shown to reach into large-scale stratospheric intrusions (depressions of stratospheric air lying well below the lapse-rate tropopause on the cyclonic side of upper troposphere jet streams – or “tropopause folds”, typically identified via potential vorticity). Such stratosphere-reaching convection is not captured by studies of lapse-rate tropopause-overshooting convection. Here, 22 years (1996-2017) of hourly Gridded NEXRAD WSR-88D Radar (GridRad) data over the United States and 6-hourly output from the ERA-Interim reanalysis are leveraged to evaluate both variants of convection reaching the stratosphere. Geographic distributions, time analyses, and transport calculations (from trajectories) will all be discussed. Bonus: overshooting by the “billion dollar derecho” that greatly impacted Iowa and neighboring states in August 2020 will be highlighted.