Inversion Of Ocean Surface Current And Tide Measurement Based On GPS Buoy Data

Ocean currents and tides,as two important phenomena in the ocean,have a huge impact on the national economy,the climate and human life.At present,there are many methods for observing currents and tide levels.Although existing methods can achieve effective measurements of currents and tide levels,there are also significant shortcomings.Traditional methods of ocean current observation usually use current meters fixed on offshore platforms for contact measurements.Instruments and equipment are usually expensive,and long-term observations are likely to cause damage and loss of the instrument.The traditional tidal level measurement method is generally to establish tide gauge stations at fixed stations,which is more constrained by the location.As a new type of ocean observation instrument,GPS buoy has the advantages of all-weather,high precision and low cost.In recent years,using GPS buoy data to invert and measure ocean parameters has become a research hotspot.In this paper,the GPS buoy is applied to the inversion and measurement of ocean parameters.The combination of theory and experiment is used to invert the surface current velocity and extract the tide sequence by using GPS buoy data.The speed of the buoy is obtained by the GPS absolute velocity determination.Compared with the measured surface current velocity,the results show that the variation period of the buoy velocity and the current velocity is highly consistent.The ratio of the two is approximately 1/360.The direction and phase are also very consistent.The motion of the buoy at sea is numerically calculated.The motion equation of the buoy is deduced by using Euler parameter method.The turbulence model of the Reynolds average method is constructed,and then the buoy is simulated in seven working conditions.The simulation results show that the displacement and velocity of the buoy are consistent with the experimental results.The model has good stability and can provide effective guidance for further research work.By constructing the GPS tide gauge model and using the measured GPS buoy antenna elevation data,the tidal level of the buoy is extracted by subtracting the antenna height,vertical reference transformation and tidal level filtering.The feasibility of this method is verified by comparing with the tidal level data of the nearby tide gauge station.Based on the data of the tide gauge and the measured ocean current data,the harmonic constants of tides and tidal currents are calculated by harmonic analysis method,and the tidal characteristics and tidal current characteristics of Tianjin Port are studied.The results show that the tides in Tianjin Port belong to irregular semidiurnal tides and the tidal currents belong to regular semidiurnal tides.Wind has an important influence on surface residual currents.Through the research in this paper,it can provide a new method for ocean current measurement and realize tidal level extraction by using GPS technology,to make up for the deficiency of traditional ocean current inversion method and tidal level measurement method.The analysis of tidal current and tidal characteristics has deepened the understanding of the marine dynamic environment of Tianjin Port.The numerical model of buoy motion proposed in this paper can provide the dynamic parameters of buoys and provide effective guidance for accurate inversion of ocean currents.