Nonintrusive Measurement of Ocean Waves: Lidar Wave Gauge

Abstract

In December 1999, a nonintrusive directional lidar wave gauge (LWG) was field tested at the Field Research Facility (FRF) in North Carolina. The LWG uses proven lidar technology to directly measure water surface elevation from above the water?s surface. Therefore, unlike bottom-mounted gauges, the surface elevation measurement from the LWG is independent of other hydrodynamic processes. The LWG prototype consists of four rangefinders, where each collects water surface elevation time series at a rate of 10 Hz. During the field test, ground truth data were collected concurrently with the LWG data using a biaxial current and pressure meter mounted directly beneath the LWG. Additional ground truth data were available from the existing FRF wave-gauging infrastructure. This paper describes principles of LWG operation and field experiment setup, LWG environmental and technical constraints, and LWG performance in measuring spectral wave parameters.