Research On Algorithms Of Ocean Wave Measurements Based On Satellite GPS Signals

Ocean wave is an important agent in the marine dynamic environment.Observations and predictions of ocean waves with high precision are of great significance for marine disaster prevention and mitigation.Wave buoys are currently the most widely used wave measuring device.The measurement method using GPS satellite signals is different from of the traditional gravity acceleration wave buoy in its mechanism.This paper aims at studies of the measurement method using GPS satellite signals.The main research results of this paper are summarized as follows:(1)The algorithm model of measuring waves based on GPS satellite signals was studied systematically.The feasibility and effectiveness of this algorithm model were verified by synchronous observations using GPS wave buoys,Waverider buoys and the AWAC wave tide instrument.(2)A modified algorithm model based on nonlinear autoregressive neural network was proposed for tackling the problem of abnormal data occurring in the data sequence of the buoy velocity when antenna of the GPS wave buoy is occasionally covered by the seawater.By combining with Gaussian low-pass filter,the accuracy of GPS satellite signals for wave measurement was further improved,and the feasibility and effectiveness of this modified algorithm model were verified through on-site tests.(3)The consistency and stability of GPS satellite signals for wave measurement algorithm were studied in terms of wave heights,wave periods,wave directions,ocean wave spectrum,top-five-coefficient and frequency energy distribution.(4)A modified algorithm model based on the first-five-coefficient was presented for tackling the low accuracy problem of the wave measurement method based on GPS signals due to the poor wave-following performance of the wave glider carrier.Through on-site tests,the accuracy of wave measurement based on wave glider carrier was improved,and the feasibility and effectiveness of this correction algorithm were verified.(5)The numerical simulation of sea state was carried out using WRF mode and SWAN mode,and the simulation results were verified by the field wave data of the GPS wave buoy.A modified algorithm model based on nonlinear autoregressive neural network was presented,and the model was used to improve the accuracy of prediction for wave sequence at specific positions of the wave field.On-site sea tests shown that the modified algorithm model is helpful in improving the prediction accuracy of waves.