Research On Velocity Field Inversion Based On Ray Theory

Acoustic method is the main method of current measurement.Acoustic doppler flow profiler(ADCP)is developed by using sound wave propagation in sea water.It is suitable for single station or walking-type velocity measurement,and not suitable for large range,long time and continuous velocity synchronous observation.Temperature and salinity depth meter(CTD)can collect temperature,salinity and depth data at the same time.In order to obtain more three-dimensional data,it needs to be put more times,which will produce higher cost of money and time.Acoustic inversion is one of the most effective methods for realtime and continuous monitoring of velocity field in large area of sea.At present,the coastal acoustic tomography system developed is a real-time observation system,and the data processing and flow field inversion also need some real time.Therefore,how to accurately and quickly invert the Marine velocity field becomes a necessary problem.In this paper,the inversion method of Marine parameter velocity is studied.Based on the acoustic line travel time tomography,the distribution of seawater velocity and sound velocity can be effectively reflected by combining the reciprocal propagation time difference,matching field method,extended empirical orthogonal function(EEOF)analysis method and equivalent segmentation method.The effective signal receiving time is obtained after preprocessing by using the actual collected signal.The obtained time data is used for further inversion,and a stable inversion algorithm is developed to enable real-time monitoring.The main purpose of this study is to realize fast and stable ocean flow field inversion algorithm,implement real-time calculation and establish a whole set of data preprocessing and postprocessing methods,so that the inversion method of this study is applicable to real-time processing of coastal acoustic tomography system.This study involves digital signal processing and computer application technology,interdisciplinary and combined theoretical knowledge,and has certain academic value.Acoustic method is the main method of current measurement.