Combined Radar Monitoring of Long Surface Wave Packets in the Pacific Ocean

Abstract

In order to continue and more detailed study of the manifestations of seismic activity on the World Ocean surface, in this work we verified the complex technique of airborne radar monitoring and research of long surface wave packets in the seismically active region in the Northwest Pacific Ocean near the Kuril-Kamchatka Trench. When verifying the technique proposed in the previous work, we used data from two series of radar surveys of the sea surface within the study area in the 3-cm range of radio wave lengths. The first series of radar surveys had included tacks of flights along the north–south direction, to which, for comparison, the results of the second series in the west–east direction were added. These radar images, presented in the work, detect manifestations of two surface wave packets propagating from the same area, in the same direction, with an interval of 16 hours. For a comprehensive study of surface wave packets based on a set of radar images of two series and to establish the nature of their origin, a combined spatial and spectral analysis of the nonlinear form of the wave packet components was performed. As a result, the spatial scale of surface wave packets (5–10 km), the lengths of the wave components of the packets (1–5 km) and the speed of packets movement (6.1 m/s) were determined. The analysis involved the parameters of the ocean-atmosphere near-surface layer, provided by operational in situ measurements, which were obtained by the research vessel "Akademik Petrov". This included the direction and speed of the near-surface wind, the state of wind waves and swell, the speed of the surface current, etc. In addition, data on bathymetry along the path of the surface wave packet and seismic activity in the area were used. Finally, it was assumed that the observed packets of surface waves are Korteweg – de Vries solitons, which arise as a result of collapses on the steep underwater slopes of the Kuril-Kamchatka Trench due to a seismic shock and the aftershock that followed it. The developed airborne radar technique can also be used in satellite monitoring of the surface of the World Ocean in systems for warning about the approach of potentially dangerous long waves to the coast.