[Eoas-seminar] **REMINDER***REMINDER*** THIS MORNING***GFDI Seminar & Dissertation Defense on MONDAY, APRIL 2nd, at 11:00AM in Melvin Stern Seminar Room, #18 Keen Bldg.

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Mon Apr 2 09:58:41 EDT 2018

*********REMINDER********REMINDER********This Morning, APRIL 2nd************

&                                                                         GFDI SEMINAR                                                                                     &



“Baroclinic, Geostrophic Turbulence and Jets

in the Laboratory”


Mr. Carlowen Smith

GFDI Ph.D. Candidate

(Major Professor: Dr. Kevin Speer)

Time and Place

11:00AM, Monday, April 2, 2018

Melvin Stern Seminar/Reading Room

018 Keen Building

Dissertation Defense will follow the seminar

ABSTRACT: Baroclinic, geostrophic turbulence is random, chaotic flow characterized by significant vertical gradients in density (Bu  << 1) in which rotation plays a major role (Ro  << 1). In the presence of a large-scale background gradient of potential vorticity (a β-effect), a symmetry-breaking occurs which admits anisotropy in the system. These conditions form the fundamental dynamical basis of many natural geophysical flows on a planetary scale (Rh << 1), and even fairly simple models of these phenomena can exhibit quite complex behavior. One aspect that is common to these flows is that of multiple, zonal jets. These are spontaneous flow structures characterized by fast East-West (azimuthal) motion.

This thesis describes the creation of multiple jets in the laboratory within a fully-stratified, baroclinically-forced fluid subject to rotation and a β-effect. By carefully controlling the forcing parameters, we observe the transition between a single “classical” baroclinic wave and regimes that closely resemble conditions of natural planetary flows. Observing this transition in the laboratory shows that the proposed scaling arguments are valid and have predictive power in the case of multiple zonal jets in a baroclinic fluid. Spontaneous eddy forcing of the mean flow is shown to be the ultimate driving force of the jets, whose evolution is observed in time. A long-duration drift in the jet structure is observed and quantified to be an order of magnitude less than the Rossby wave drift speed.

A detailed quantitative analysis of the structure the flow field sheds further light. There is a significant transition of the power law scaling of Fourier spectra between dynamically significant scales. As the flow changes between experiments, the spectral power law can change over particular scale ranges, which is direct evidence of a regime change.

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