2016-03-23 Cory Barton Defense
“Spatio-Temporal Evolutions of Non-Orthogonal Equatorial Wave Modes Derived from Observations”
Geophysical Fluid Dynamics Ph.D. Candidate
Florida State University
(Major Professor: Dr. Ming Cai)
Time: Wednesday, March 23, 2016 at 1:00PM
Place: Melvin Stern Seminar Room Room 18 Keen Bldg.
Dissertation Defense will follow the seminar
Abstract: Equatorial waves have been studied extensively due to their importance to the tropical climate and weather systems. The non-orthogonality of wave modes has yet posed a problem when attempting to separate data into instantaneous wave fields where the waves project onto the same structure functions. We propose the development and application of a new methodology for equatorial wave expansion of instantaneous flows using the full equatorial wave spectrum. By mapping the meridional structure function amplitudes to the equatorial wave class amplitudes, we are able to diagnose instantaneous wave fields and determine their evolution.
The wave class spectra diagnosed assuming the peak projection response depth scale mostly match their expected dispersion curves, showing that this method successfully partitions the wave spectra by calculating wave amplitudes in physical space. This is particularly striking because the time evolution, and therefore the frequency characteristics, is determined simply by a timeseries of independently-diagnosed instantaneous horizontal fields. Vertical tilting in the wave fields is similarly diagnosed across multiple pressure levels. We have confirmed the continuous evolution of the QBO selection mechanism for equatorial waves in the tropical middle atmosphere and additionally identified a time-evolution of the zonal wavenumber spectrum responsible for the amplitude variability in physical space. Read More