Registering the Peculiarities of Wind Wave Breaking from Unmanned Aerial Vehicles

Abstract

The results of using an unmanned aerial vehicle (UAV) to study the processes of gravitational wave breaking are presented. The experiments are carried out in the coastal zone of the western Crimea (the area of Sevastopol) in the range of wind speeds from 5.5 to 9.5 m/s. The determination of the geometric dimensions of breaking and their speeds is carried out according to video recordings of the sea surface obtained from the UAV. It is shown that the spatial resolution of the transformed image plays a key role in separating the active phase of breaking and residual foam. Errors occur in determining the kinematic properties of the breaking with a rough spatial resolution. The proportion of the sea surface covered with foam of breaking waves, the ratio of the maximum length of the spume to the length of the breaking wave, and the distribution of the total breaking length in the intervals of movement speeds per surface unit (obtained from UAVs with a spatial resolution better than 0.5m) are in agreement with results of other authors. Data analysis shows that the use of UAVs makes it possible to study the statistical characteristics and kinematics of wind wave breaking. At the same time, it is necessary to take into account the effect of spatial resolution in the video frame, which can lead to the distortion or omission of measurement data at values comparable to or exceeding the breaking scale.