Underwater wave phenomena in the upper ocean and their surface manifestation: Role of nonlinearity

In this contribution, we present the review of recently developed models of surface manifestation of underwater processed in the upper ocean and some results of their verification in laboratory and field experiments. Influence of modulation of wind growth rate on variability of short gravity surface waves is discussed. This effect is demonstrated to be the most important for forming the hydrodynamic contract of the waves in the field of the swell wave, although it make essential contribution to modulation of surface waves by the field of meso-scale currents internal gravity waves, flows above bottom topography). The nonlinearity of the wind-wave interaction determines the phase of surface wave modulation wit respect to meso-scale flow. Some results of the field experiments are presented. For example, field measurements in the Black Sea, the Norwegian Sea and Barents Sea demonstrated strong variability of the surface wave spectra and associated variability of the surface wind in the vicinity of the underwater local bottom ele-vation. We compared the experimental data an the developed theory, which demonstrates very good quantitative agreement. Also we discuss possibility of detection of a tsunami wave in the upper ocean by modulation of radio-waves scattered by waved rough water surface. A first example of observation of modulation of the cross-section of the radar altimeter on the satellite Jason-1 by the tsunami in the upper ocean 26 December 2004 is presented. The possible mechanism of the modulation is proposed based on the effect of modulation of the growth rate of weakly nonlinear surface waves. We discuss influence of nonlinearity of spectrally narrow train of surface waves on its transformation in the field of inhomogeneous surface current. The asymptotical model is constructed based on taking into account dispersion and nonlinear effects of high order, the numerical modeling of propagation of a surface wave train is performed. The results of the model are compared with the date of laboratory modeling in the large thermostratified tank of IAP.