A numerical study of barotropic instability of a zonally varying easterly jet.
Authors
Tupaz, Jesus Bonifacio
Subjects
Advisors
Chang, C-P
Williams, R.T.
Date of Issue
1977-06
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
The structure and behavior of barotropi cal ly unstable
and stable wave disturbances in the vicinity of a zonally
varying easterly jet are studied numerically with a
linearized barotropic vorticity equation on a B-plane. The
easterly jet is approximated by a Bickley jet with a slow
zonal variation. The numerical results are also compared
with a simple mechanistic analytical model using the local
phase speed and growth rate concepts. The results are
grossly similar in several respects to that expected from
the parallel flow theory of barotropic instability, however,
the resultant structure of the waves causes a spatial growth rate greater than predicted by the local growth rates
computed with a parallel flow model. In the stable region,
the structure leads to strong dynamic damping. When a
uniform advective velocity is added to a variable mean flow,
the differences between the behavior of the computed waves
and that implied by the parallel flow theory are somewhat
reduced. The waves remove kinetic energy from the mean
flow and most of this energy is removed on the downwind side
of the jet. The computed structure and behavior of the waves have a number of features that resemble those observed in
the vicinity of the upper troposphere easterly jet during
the summer monsoon.
Type
Thesis
Description
Series/Report No
Department
Meteorology
Organization
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.