Accuracy Test And Error Analysis Of Significant Wave Height Inversion In WaMoS ? Wave Measuring Radar System.

Waves are a very common and important physical phenomenon in the ocean.Understanding,studying and utilizing waves is a significant step for mankind beings to develop the ocean field.The Hs(significant wave height)of waves is an important design parameter in protection of coastal port facilities,the safety of maritime navigation and the exploitation of marine resources.In recent years,the application of x-band radar system to extract wave information is gradually becoming a research focus.In this paper,by studying the Wa Mo S ? wave measuring radar system installed on the "XYH03" research vessel,the external factors affecting the Hs measurement are analyzed in view of the problems existing in the inversion of the Hs.In order to better understand Wa Mo S ? wave measuring radar system,this paper first introduces Radar Cross Section,radar equation,radar resolution,radar polarization and other knowledge involved in radar wave remote sensing measurement.Then the basic imaging principles of Bragg scattering,shadow modulation,tilt modulation,hydrodynamic modulation and orbital modulation are described.Then,the software and hardware of Wa Mo S ? wave measuring radar system and the process of wave information inversion are introduced in detail.After analyzing the working principle of Wa Mo S ? wave measuring radar system,this paper compares the Hs data retrieved by the wave measuring radar system during six offshore tests from June 2017 to April 2018 with the Hs data obtained by other wave measuring methods.It is found that the overall changes of the two is relatively consistent,and the average error is within the allowable range of radar system error.In order to further judge the influence of abnormal Hs data retrieved by the radar system on the overall result,the abnormal data with absolute values above 2.0m,above 1.0m and above 0.5m are removed respectively,and the comparison measurement after removing the abnormal data is classified and discussed.It is found that the abnormal data has a great influence on the result.Then,accordingIX to the Hs(significant wave height)obtained by other wave measurement methods,the actual sea state is divided into four sections: <1m,1-2m,2-3m and 3-4m.The distribution of mean error and root mean square error of Hs in different sections is discussed respectively.It is concluded that the inversion result of the Hs of the wave measuring radar system is ideal under the medium-high sea conditions of 1-2m and2-3m,and the average error and root mean square error are small.Under low sea conditions of <1m,the mean error and root mean square error of Hs are large.Under high sea conditions of 3-4m,the average error and root mean square error of Hs are the largest.Then,the distribution of mean error of Hs and root mean square error of Hs in the four sections of wind speed <5m/s,5-10m/s,10-15m/s and 15m/s,and the included angles of wind direction and wave direction in the four sections of <45°,45-90°,90-135° and 135-180° are further analyzed.It is found that when the wind speed is less than 10m/s and the included angle between the wind direction and the wave direction is 45-180,the accuracy of Hs inversion of the wave measuring radar system is relatively low.When the wind speed is less than 10m/s and the included angle between wind direction and wave direction is less than 45,the Hs inversion accuracy of the wave radar system is higher.In order to explore the influence of rainfall on the Hs(significant wave height)inversion of Wa Mo S ? wave measuring radar system,the Hs data retrieved by the radar system and the Hs data manually measured during the offshore observation on December 5,2017 and 6,2017 were analyzed.Comparative analysis of one-dimensional spectrum and two-dimensional wave spectrum at 15:00 and 15:30 on December 5 and 12:30 and 13:30 on December 6 when the Hs is 3.5m and the wind waves are dominant in the sea state.And the one-dimensional spectrum and two-dimensional wave spectrum at 16:30 and 17:00 of December 5 and 16:00 and16:30 of December 6 when the Hs is 2.5m and the wind waves are dominant.Through spectrum analysis,it was found that the spectrum energy was greatly reduced under the influence of rainfall,and the two-dimensional wave spectrum showed bimodal distribution,and the spectrum peak shifted to the direction of low wave number.And the one-dimensional spectrum and two-dimensional wave spectrum at 16:30 and17:00 of December 5 and 16:00 and 16:30 of December 6 when the Hs is 2.5m and the wind waves are dominant.