L1.1 Potential Vorticity Aspects of Tropical Cyclones (Invited Presentation)

Wednesday, 28 June 2017: 6:00 PM
Salon F (Marriott Portland Downtown Waterfront)
Wayne Schubert, Colorado State University, Fort Collins, CO

In the late 1930's, after coming to the US, Bernhard Haurwitz

(1905-1986) became interested in hurricanes. There was a debate about the depth of the hurricane circulation. Some thought hurricanes only extended up to about 700 mb. Bernhard cleared up this confusion using a simple theoretical analysis. He remained interested in tropical meteorology throughout his life. We now think of tropical cyclones as balanced phenomena, i.e., with hydrostatic balance in the vertical direction and gradient balance in the radial direction. They can be considered an extreme type of PV phenomenon. We will consider several questions that arise: (1) How is a PV tower formed? (2) How is a hollow PV tower formed? (3) How can a hollow PV tower become dynamically unstable? (4) Can the PV in a tropical cyclone exceed 250 PV units? (5) Can we invert the moist PV to find the balanced wind and mass fields?(6) Can the mass field in a tropical cyclone become "spicy", as the ocean does? (7) What is the Ekman pumping formula for a tropical cyclone, and can the tropical cyclone boundary layer produce shocks and therefore singularities in the Ekman pumping?

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