Sea wave dynamics visualization and its interaction with the surface atmosphere by LED mini lidar

摘要

LED mini lidar has been developed and installed into the sea wave dynamics visualization. This study aims minilidarinstallation to small fishing ship and pleasure boat. In the viewpoints of its safety and robustness of the installedsystem, LED pulse beam was selected as the lidar light source. Its shallow angle observation visualizes the sea wavemotion from just a front of the ship to 300m ahead. At the coast experiment, two types of LED mini lidars were usedfor polarization measurement and Raman scattering measurement. They were almost the same optical characteristicsexcept for their LED wavelength, that is, 365nm for polarization lidar and 365nm for Raman lidar. To visualize thesea wave dynamics, the summation time was shortened to 0.2s. The shallow angle (depression angle) of the lidarobservation was set in 2 – 10 degrees against the horizontal direction. The fundamental information of sea wave,which were wave speed, height, period and wavelength, was deduced from the lidar echo. The polarization echomeasurement revealed its dependency due to the LED beam incident angle against the sea surface. The Raman echomeasurement visualized the correlation between the surface atmosphere activity and the sea wave dynamics. Thesurface atmosphere activity on water vapor Raman echo related to the sea wave motion from the fluorescentbackscattered light of sea water, while it had its original change. These results are valid for safe cruise of small boat.This additional sea wave activity information will be effective for low fuel consumption operation and the automaticcontrol in safety cruise. They are also of interest in physical oceanography.