Internal Gravity Waves in the Ocean with Two Pycnoclines: Models and Dynamics

The kinematic and amplitude characteristics and shape of fully nonlinear solitary impulses of both polarities in almost three-layer ocean are investigated in this work. The existence of limiting broad solitary-like flat-top waves is proved for this medium with zero quadratic nonlinearity. The dependencies of speed, width and integrals of mass and energy from soliton amplitude are shown. Qualitatively different nonlinear wave regimes are demonstrated depending on the form of initial disturbance and on the relative layer thicknesses. Conjugate flows are considered; this phenomenon appears while limiting broad impulses are propagating. The limiting amplitude of broad solitary waves is analysed subject to layer thicknesses, point of bifurcation of wave regimes is determined. The comparison with weakly nonlinear theory is fulfilled.