Enhancement of wave transmissions in multiple radiative and convective zones

TL;DR

This paper investigates how wave transmission in a rotating fluid with multiple layers can be significantly enhanced through resonant phenomena, even in strongly stratified conditions, by analyzing wave propagation and tunneling mechanisms.

Contribution

It introduces the concept of enhanced wave transmission via resonant propagation and tunneling in multilayer rotating fluids, detailing conditions for their occurrence and implications.

Findings

Enhanced wave transmission occurs only with an odd number of layers.

Resonant conditions require layer properties and thicknesses to match specific multiples of half wavelengths.

Efficient tunneling occurs when embedded layers are much thinner than decay distances.

Abstract

In this paper, we study wave transmission in a rotating fluid with multiple alternating convectively stable and unstable layers. We have discussed wave transmissions in two different circumstances: cases where the wave is propagative in each layer and cases where wave tunneling occurs. We find that efficient wave transmission can be achieved by `resonant propagation' or `resonant tunneling', even when stable layers are strongly stratified, and we call this phenomenon `enhanced wave transmission'. Enhanced wave transmission only occurs when the total number of layers is odd (embedding stable layers are alternatingly embedded within clamping convective layers, or vise versa). For wave propagation, the occurrence of enhanced wave transmission requires that clamping layers have similar properties, the thickness of each clamping layer is close to a multiple of the half wavelength of the corresponding propagative wave, and the total thickness of embedded layers is close to a multiple of the half wavelength of the corresponding propagating wave (resonant propagation). For wave tunneling, we have considered two cases: tunneling of gravity waves and tunneling of inertial waves. In both cases, efficient tunneling requires that clamping layers have similar properties, the thickness of each embedded layer is much smaller than the corresponding e-folding decay distance, and the thickness of each clamping layer is close to a multiple-and-a-half of half wavelength (resonant tunneling).