Journal of Marine Science and Engineering Article Method of Studying Modulation Effects of Wind and Swell Waves on Tidal and Seiche Oscillations Grigory Ivanovich Dolgikh 1,2,* and Sergey Sergeevich Budrin 1,2,* 1 V.I. Il’ichev Pacific Oceanological Institute, Far Eastern Branch Russian Academy of Sciences, 690041 Vladivostok, Russia 2 Institute for Scientific Research of Aerospace Monitoring “AEROCOSMOS”, 105064 Moscow, Russia * Correspondence:
[email protected] (G.I.D.);
[email protected] (S.S.B.) Abstract: This paper describes a method for identifying modulation effects caused by the interaction of waves with different frequencies based on regression analysis. We present examples of its applica- tion on experimental data obtained using high-precision laser interference instruments. Using this method, we illustrate and describe the nonlinearity of the change in the period of wind waves that are associated with wave processes of lower frequencies—12- and 24-h tides and seiches. Based on data analysis, we present several basic types of modulation that are characteristic of the interaction of wind and swell waves on seiche oscillations, with the help of which we can explain some peculiarities of change in the process spectrum of these waves. Keywords: wind waves; swell; tides; seiches; remote probing; space monitoring; nonlinearity; modulation 1. Introduction Citation: Dolgikh, G.I.; Budrin, S.S. The phenomenon of modulation of short-period waves on long waves is currently Method of Studying Modulation widely used in the field of non-contact methods for sea surface monitoring. These processes Effects of Wind and Swell Waves on are mainly investigated during space monitoring by means of analyzing optical [1,2] and Tidal and Seiche Oscillations.