Multiple Tropopauses:
A Major Source of Middle-Atmospheric Gravity Waves

Manabu D. Yamanaka and Shoichiro Fukao
Radio Atmospheric Science Center, Kyoto University, Uji, Kyoto 611, Japan


Solar Terrestrial Energy Program: The Initial Results from STEP Facilities and Theory Campaigns, D. N. Baker, V. O. Papitashvili and M. J. Teague (eds.), Pergamon Press, London, pp.453-461.

Paper No. MA7 (an invited talk) presented at the 1992 STEP Symposium/5th COSPAR Colloquium, Laurel, August 1992; which was a meeting related to the 29th COSPAR Plenary Meeting, the World Space Congress, Washington D.\ C., USA, 28 August-5 September 1992.
First draft: February, 1992; Submitted: late 1992; Accepted: early 1993
Published: February, 1994


ABSTRACT , CONTENTS , CORRECTIONS , FIGURES , REFERENCES , CITATIONS


Abstract
On the basis of MU radar and routine network observations since 1985, we consider the dominant mode of lower-stratospheric inertio-gravity waves as ``multiple tropopauses'' which compensate an imbalance of one-dimensional radiative-convective equilibrium. Turbulence layers parallel to such wavy structures are regarded as ``mini-tropospheres'', and secondary waves generated by wavebreaking may propagate upward and become dominant modes in the higher altitude regions. Spectral and monochromatic analyses of observational results obtained by a three-week continuous MU radar operation during 17 June-8 July 1991 show that the dominant wave parameters in the tropopause region have a temporal variability of 10--20% with a characteristic scale of 2--3 days, which is correlated to activities of the medium (or meso-$\alpha$) scale disturbances on the subtropical ( Baiu ) front in the troposphere. Another case study on a strong typhoon, which approached to the MU radar observatory at a distance of only 30 km in the midnight of 19-20 September 1990, shows that the typhoon was gradually changed to a medium-scale extratropical cyclone on the subtropical ( Shurin ) front with multiple tropopauses.


Contents
Introduction
Significance of Multiple Tropopauses
500-Hour Observations by the MU Radar
A Case Study on Typhoon Transformation
Conclusion


Corrections and Additional Remarks


List of Figures (No Tabales)


References (Updated after publication)


Citations by Subsequent Papers
(Under construction !!!!!)


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