Physical Oceanography, Vol. 16, No. 2, 2006
GENERATION OF QUASIINERTIAL INTERNAL WAVES IN THE PROCESS
OF EVOLUTION OF LOCAL PERTURBATIONS IN THE OCEAN
S. F. Dotsenko
Within the framework of a linear model of long waves in a two-layer ocean, we obtain the analy-
tic solution of the problem of evolution of an axially symmetric initial displacement of the jump
of density. In the process of adaptation of the fields, internal waves in the form of a decaying (in
time) wave packet are emitted from the zone of initial perturbation. These waves are quasiiner-
tial and their dispersion is conditioned by Earth's rotation. We study the time evolution of the
wave packet and the dependence of its characteristics on the width of the zone of initial perturba-
tion and the depth of the jump of density.
The analysis of the dynamics of local perturbations in a stratified ocean is traditionally of great interest for
oceanology. The process of modeling of evolutionary processes of this kind allows us to estimate the efficiency
of generation of internal waves by local perturbations of the hydrophysical fields, evaluate the contribution of
various baroclinic modes to the variability of the ocean, and describe both the specific features of the emission of
internal waves from the zones of generation and the laws of their decay in space and time. The local perturba-
tions can be interpreted, e.g., as the zones of turbulent mixing, the response of the ocean to short-term atmosphe-
ric actions, or seismic displacements of the bottom.
The linear models of the evolution of local perturbations in the ocean are especially well developed. These
models enable one to find the exact integral solutions of the problems and perform their subsequent analysis with
the help of asymptotic or numerical methods. The asymptotic laws of decay of internal waves are studied for
continuously stratified and two-layer oceans [1–5]. The dynamics of emitted waves in two-layer and continu-
ously stratified oceans of constant depth is studied on the basis of the numerical analysis of integral solutions in
[4–7] and some other works.
The frequency spectrum of the time variability of hydrophysical fields is quite broad . Note that the con-
tribution of quasiinertial oscillations to the variability of the ocean is significant. The oscillations of the fields in
the ocean are, as a rule, superinertial, although the oscillations with subinertial frequencies are also recorded in
some cases . It is also of interest to study all possible mechanisms of generation and the properties of quasi-
inertial oscillations of the oceanic fields.
In what follows, within the framework of a two-layer model of the ocean, we analyze one of possible mech-
anisms of the formation of quasiinertial oscillations of the fields. The waves are generated due to the presence of
an initial axisymmetric displacement of the jump of density. Our investigation is based on the numerical analy-
sis of the integral solutions of the linear problem. Main attention is given to the study of the properties of the
packets of quasiinertial internal waves emitted from the zone of initial perturbation. The results of previous in-
vestigations are supplemented by the analysis of the dispersion of internal waves caused by Earth’s rotation and
the relationship between the characteristics of these waves and the parameters of the initial perturbation of the
ocean and density stratification.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol. Translated from Morskoi Gidrofizicheskii Zhurnal,
12–23, March–April, 2006. Original article submitted February 1, 2005.
0928-5105/06/1602–0077 © 2006 Springer Science+Business Media, Inc. 77