Propagation and Breakdown of Internal Inertio-Gravity Waves
near Critical Levels in the Middle Atmosphere

Manabu D. Yamanaka
Institute of Space and Astronautical Science, Meguro, Tokyo 153, Japan

and Hiroshi Tanaka
Water Research Institute, Nagoya University, Chikusa, Nagoya 464, Japan


Journal of the Meteorological Society of Japan , vol.62, no.1, pp.1-17.

A part of M.Sc Thesis by M. D. Yamanaka submitted to Graduate School of Science, Nagoya University in February 1982, accepted in March 1982.
First manuscript received: December 28, 1982;
Final manuscript accepted: December 6, 1983
Published: February, 1984


ABSTRACT , CONTENTS , CORRECTIONS , FIGURES , REFERENCES , CITATIONS


Abstract
Behaviors of internal inertio-gravity waves (IIGW) near Jones' critical levels are studied theoretically in view of a possible origin of turbulence layers in the middle atmosphere. The inertial effect associated with the earth's rotation cannot be neglected when time constant of the wave is large. Assuming that the vertical shear and Coriolis factor are constant, exact solution of IIGW are obtained from inviscid and linear equations. The asymptotic expressions are derived by means of the Liouville-Green method developed by Olver (1974) which leads to an exact dispersion relation near the critical levels. Two important features about critical level problem of IIGW are found from the dispersion relation: valve effect across the Jones' critical levels in somewhat different sense from Grimshaw (1975, 1980), and presense of a pair of turning levels between both Jones' critical levels. Coupling these features, we predict that IIGW is absorbed or reflected by the Jones' critical levels depending on the directions of wave-front. The absorption rate and the thickness of turbulence layer produced by critical level breakdown increase as the wave-fronts tend to direct to the zonal direction, on the other hand IIGW is substantially reflected when they direct to the meridional direction. With increase of basic Richardson number the turning levels approach asymptotically the critical levels, so that turbulence layers inside the critical levels become thinner than those outside them. These features vanish in the course of non-inertial gravity waves.

The relation between IIGW and turbulence layers is calculated to compare with the turbulence layers observed in the stratosphere and to have information on IIGW's propagating upwards to the mesosphere and thermosphere. In general, thickness of the turbulence layers associated with IIGW's is thinner than that associated with non-inertial gravity waves for common mesoscale wavelength domain.


Contents
1. Introduction
2. Equations and Solutions
2.1. Governing Equations
2.2. Exact Solutions
2.3. Asymptotic Solutions
3. Vertical Propagation of IIGW in a Shear Flow
3.1. Local Dispersion Relation
3.2. Propagation of IIGW far from the Critical Levels
3.3. Propagation in the Vicinity of Jones' Critical Levels
4. Wave Behaviors near Jones' Critical Levels
4.1. Valve Effect
4.2. Turning Levels
4.3. Wave Absorption Associated with Jones' Critical Levels
5. Formation of Turbulence Layers
5.1. Local Convective Instability
5.2. Turbulence Layers Generated by IIGW Breakdown
6. Conclusion
Appendix A: Notations
Appendix B: Treatment for f = 0
Appendix C: Treatment for l = 0
Appendix D: Liouville-Green Method Developed by Olver (LGO Method)
Appendix E: Examples of LGO Method
Appendix F: Group Velocity near Jones' Critical Level


Corrections and Additional Remarks


List of Figures (No Tabales)


References (Updated after publication)


Citations by Subsequent Papers


  • List of Original Papers by M. D. Yamanaka

  • Bibliography by any authors


    M. D. YAMANAKA homepage (English)


    E-mail : yamanaka@kurasc.kyoto-u.ac.jp