Research On The Characteristics Of Navigation Radar Rain Clutter And Its Influence On Wave Measurement

Marine monitoring can play a great role in port construction,navigational safety,marine disaster prevention and the development of military strategy.Studying the influence of rainfall on navigating radar to measure waves can estimate the precision of using radar image to invert ocean wave parameters during rainfall so as to provide an evaluation index for better monitoring of ocean.This article is based on the research project "Ship-borne X-band Navigation Radar Inversion Technique".Based on a large number of data of real-time navigational radar images and rain gauges,the error mean and error standard deviation of sea wave parameters retrieved by using X-band navigation radar images under different rainfall intensities are analyzed.Firstly,a large number of experimental data are used to analyze the characteristics of radar image under different rainfall intensities.The results show that the average intensity of radar images increases with the increase of rainfall intensity,while the zero intensity percentage of radar images decreases gradually.Based on this,a method of using K parameters of radar image occlusion area to retrieve rainfall intensity is proposed in this paper,K parameter is defined as the ratio of the zero intensity percentage and the mean value of echo intensity in radar image occlusion area.Secondly,the monotonicity between the K parameter of the radar image and the rainfall intensity is analyzed.By using the measured radar image and rainfall,The relationship between K parameter and rainfall intensity was curve-fitted.Finally,the K parameter of other radar image obscuration zone is substituted into the fitted curve to verify the feasibility of this method to invert rainfall intensity.The correlation between the inversion value and rainfall value is proved to be effective.Aiming at the research of the influence of rainfall on navigation radar,the paper first analyzes the factors that influence rainfall measurement from the theory of using single radar image to extract ocean wave information.The conclusion shows that rainfall can increase the echo intensity of radar image and reduce the image of navigation radar signal to noise ratio.Secondly,the paper introduces the principle and method of selecting data as the true value of ocean wave inversion parameters.Finally,based on the measured radar image and the rain gauge data,the errors of using the X-band navigation radar to invert the ocean wave parameters under the conditions of light rain,moderate rain and heavy rain are respectively analyzed.The mean errors and standard deviations of the wave parameters such as effective wave height,wave direction and Wave period under different rainfall intensities were calculated.Aiming at the rainfall grade identification software based on radar image,the paper firstly analyze the demand of designing rainfall grade identification software,and divide the software into radar image display,radar image sequence continuous playback,radar image range and color mode selection,rainfall intensity level identification and corresponding time inversion of the wave parameter error.Secondly,the functions of each module are analyzed in detail.At the same time,the data flow and working principle of each module are introduced by using data flow diagram and flow chart.Finally,the function and performance of each module are tested.