The American Meteorological Society's NYC/Long Island Chapter Seminar Series, sponsored by Columbia University's Fu Foundation School of Engineering and Applied Science, is proud to present:
Professor Gregory Tripoli
Chair of Atmospheric and Oceanic Sciences Department
University of Wisconsin
"Fueling of Catastrophic Weather Events in the Middle Latitudes by Hurricanes in the Tropics"
Abstract: Over the past two decades, an unusually large frequency of major flooding rain events, strong winter storms, severe weather outbreaks, Mediterranean Storms, and wayward polar vortices have been impacting the middle latitudes. In many of these instances, these events can be shown to be triggered by “tropical plumes” (TPs) that periodically burst poleward in an atmospheric region called the Upper Troposphere-Lower Stratosphere (UTLS), centered around 14 km above the surface. This region is in the so-called “overworld”, where the air resides above the maximum height, in the tropics, that the net radiation loss of energy to space is able to bleed off the geopotential energy placed there. Hence, air lifted to the tropical UTLS by the actions of tropical convection and tropical storms, becomes thermodynamically trapped in an overworld bubble. On the global scale, the bubble itself is dynamically trapped in tropical latitudes by the effect of the Earth’s rotation. To relieve pressure built up in the bubble, UTLS air squirts out the sides of the bubble in the form of poleward bound TPs of potential energy. In doing so, TPs transport considerable amounts of energy into the middle latitudes that eventually becomes available to fuel extratropical weather events. In this talk, we will examine the process by which tropical cyclones fill the UTLS energy bubble, and track how several hurricanes and typhoons have directly triggered the formation of consequential tropical plumes and extratropical weather events.
