Ocean Wave Measurement Using Short-Range K-Band Narrow Beam Continuous Wave Radar

Abstract

Abstract:We describe a technique to measure ocean wave period, height and direction. The technique is based on the characteristics of transmission and backscattering of short-range K-band narrow beam continuous wave radar at the sea surface. The short-range K-band radar transmits and receives continuous signals close to the sea surface at a low-grazing angle. By sensing the motions of a dominant facet at the sea surface that strongly scatters signals back and is located directly in front of the radar, the wave orbital velocity can be measured from the Doppler shift of the received radar signal. The period, height and direction of ocean wave are determined from the relationships among wave orbital velocity, ocean wave characteristics and the Doppler shift. Numerical simulations were performed to validate that the dominant facet exists and ocean waves are measured by sensing its motion. Validation experiments were conducted in a wave tank to verify the feasibility of the proposed ocean wave measurement method. The results of simulations and experiments demonstrate the effectiveness of the short-range K-band narrow beam continuous wave radar for the measurement of ocean waves.

Experimental Investigation of Ocean Wave Measurement Using Short-Range K-Band Radar: Dock-Based and Boat-Based Wind Wave Measurements

“…Here, two examples of effective footprints are given. With the conditions of the radar antenna and wind as shown in Table 1 and the same procedures of the numerical simulation as described in [11], the locations and dimensions of the effective footprints can be estimated.…”

“…The DSF component generated by wave orbital motions is introduced in our previous research [11]. It is determined from the height ( ) and period ( ) of the wave:…”

“…The amplitude spectrum is then converted into a wave height spectrum. Suppose A i is the ith component of the amplitude spectrum, then the ith component (H i ) of the wave height spectrum [11] can be calculated with:…”

“…In fact, the spectral density of the components higher than 0.64 Hz is very low and negligible. The characteristics of the wind waves are calculated with Equations ( 10) and (11) and are tabulated in Table 4. It should be mentioned that same integration limits (0 Hz ~ 0.64 Hz) are used in Equation ( 12) for both radar-and buoy-measured spectra.…”

Editorial for Special Issue “Ocean Radar”

“…Lastly, Cui et al [12] study the use of a short-range K-band narrow beam continuous wave radar for ocean wave measurements. Numerical simulations and wave tank experiments are conducted to demonstrate the technique's feasibility.…”