A conceptual view on inertial internal waves in relation to the subinertial flow on the central west Florida shelf

Ekaterina V Maksimova

doi:10.1038/s41598-018-34346-2

Abstract

The study reported here focuses on inertial internal wave currents on the west Florida midshelf in 50 m depth. In situ observations showed that the seasonal shifts in stratification change both the frequency range of inertial internal waves and their modulation time scales. According to the analysis, the subinertial flow evolution time scales also undergo compatible seasonal variations, and the inertial internal wave currents appear to be temporally and spatially related to the subinertial flow. Specifically, the subinertial flow evolving on frontal-/quasi-geostrophic time scales appears to be accompanied by the near-inertial oscillations/inertia-gravity waves in corresponding small/finite Burger number regimes, respectively. The quasi-geostrophic subinertial currents on the west Florida shelf are probably associated with the synoptic wind-forced flow, whereas the frontal-geostrophic currents are related to the evolution of density fronts. Further details of this conceptual view should, however, be elucidated in the future.

Highlights

Oceanic inertial internal waves (IIW), which include near-inertial oscillations (NIO) and inertia-gravity waves (IGW), are a subject of intense research attention because of their crucial role in energy and momentum cascades important for correct subgrid ocean and climate model parameterizations[1,2,3]
The dimensionless analysis and in situ measurements on the west Florida shelf (WFS) presented here expose an association between the NIO and FG current regimes corresponding to small Bu numbers, and an association between the IGW and QG current regimes corresponding to finite Bu numbers
The NIO and IGW currents on the WFS appear to be modulated on the same time scales as FG and QG subinertial flows, respectively (Fig. 4)

Summary

Introduction

Oceanic inertial internal waves (IIW), which include near-inertial oscillations (NIO) and inertia-gravity waves (IGW), are a subject of intense research attention because of their crucial role in energy and momentum cascades important for correct subgrid ocean and climate model parameterizations[1,2,3]. They are cited as having a significant ecological role in bringing nutrients to light by means of induced mixing in the ocean[4] and in dispersion of particles (e.g., oil-spill droplets5) at submesoscales. Petersburg, Florida (C12 in Fig. 1) in 2010, but similar conclusions apply at C10 (20 m), C14 (20 m), and C13 (50 m) on the central WFS as well

Methods

Results

Conclusion