Phys Ocean Lunch Seminar, 14 Apr 2021
Wednesday, April 14, 2021
Physical Oceanography Lunch Seminar
An analytical theory of oceanic and atmospheric spectra
U. So. Florida, College of Marine Science
12:30 P.M., via Zoom
https://washington.zoom.us/j/92031015708, Passcode: ocean2021
One tap mobile: +12063379723,,92031015708# US (Seattle)
Gather Town for socializing before and after the seminar; Passcode: ocean
ABSTRACT: Progress in the exploration of atmospheric and oceanic environments requires qualitative and quantitative understanding of various processes in anisotropic turbulence. The existing analytical spectral theories, developed for homogeneous isotropic flows, quickly become intractable when expanded to anisotropic flows with waves. Among such theories, the quasinormal scale elimination (QNSE) can nevertheless be extended to stably stratified and rotating flows. It produces analytical bi-modal expressions for horizontal kinetic energy (KE) spectra that are Kolmogorov-like on relatively small scales and Coriolis parameter-dependent on large scales. These expressions agree remarkably well with those estimated from many observations both in slopes and amplitudes. The observational spectra include the famous Nastrom & Gage spectra in the atmosphere and oceanic spectra in the vicinity of the Gulf Stream, the North-West Pacific Ocean, and ACC. The theory substantiates the general Charney’s (1971) conjecture about the affinity of atmospheric and oceanic spectra.
The theory can be used to quantify the seasonal variability of the upper ocean on meso- and submesoscales. For the former, the KE is mostly determined by the Coriolis parameter and its variability is limited. For the latter, the variability can be quantified in terms of the horizontal energy flux, Πε, proceeding from larger to smaller scales. This flux can be identified with the effective submesoscale dissipation, or ESD. The magnitude of Πε increases in winter and decreases in summer. Mirroring these changes, the bi-component structure of the KE spectra also changes with seasons.