| Summary: | The dynamical nature of atmospheric disturbances in
the Southern Hemisphere simulated by a two-level general
circulation (GCM) model is studied. Time series of the
dependent variables and diabatic heating components from
10 Southern Hemisphere winters (JJA) and summers (DJF)
simulated by the Oregon State University two-level GCM are
used. The time mean fields are presented and discussed.
Variance and covariance analyses are performed to
determine the geographical distribution, intensities and
transport properties of high-frequency (periods between
2.5 and 10 days) and low-frequency (periods between 10
days and a season) transient eddies. These are discussed
in terms of dynamical consistency with the time-mean
circulation.
It is found that the behavior of the high-frequency
eddies at mid and high-latitudes is consistent with
baroclinic instability theory, i.e., the eddies have
properties similar to observed migratory weather
disturbances. The low-frequency eddies appear to be
quasi-stationary Rossby waves originating at middle
latitudes. They seem to disperse energy in a manner
consistent with arguments based on simple linear wave
dynamics. During wintertime, the time mean flow directs
eddies poleward where they grow by baroclinic processes.
Also during wintertime, the slow phase velocity, fast
group velocity and cyclic domain lead to quasi-resonant
behavior on a hemispheric scale. === Graduation date: 1988
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