Research Of Mechanism And Method Of In-situ Monitoring Of Ice Density Based On Ultrasonic Wave

With the in-depth exploration of the polar region,the establishment of ice base parameter detection methods and databases has become one of the content of polar research in China.Through the study of ice density,the realization of reliable remote monitoring methods and means is of great significance for polar exploration and the safety of high-latitude buildings.This paper mainly studies the correlation between ultrasonic parameters and ice density,mainly studies the sound velocity and attenuation law of ultrasonic wave propagation in ice,and obtains the correlation between the sound velocity and attenuation parameters of ultrasonic wave and ice temperature and ice density of sea ice and fresh water ice.Ultrasonic waves of 1MHz and500 k Hz were used to penetrate different fresh water and sea ice and simultaneously measure the physical and ultrasonic parameters of the ice.By analyzing the experimental data,the correlation between the physical parameters such as ice density,temperature,salinity and the acoustic velocity and attenuation of ultrasonic wave passing through the ice was studied,and the inversion method of ice density based on ultrasonic wave was further summarized,which laid a foundation for the realization of ultrasonic wave based ice density monitoring.A sea ice property experiment system based on ultrasonic was designed,which realized the simultaneous measurement of ultrasonic parameters and sea ice physical parameters,including the ultrasonic parameter measurement subsystem and the sea ice parameter measurement subsystem.In this system,fresh water ice and sea ice with salinity from 9‰ to7‰ in the temperature range of-5? to-35? were taken as the research objects.The ultrasonic sound velocity was measured by using the echo method,and the correlation between the ice temperature and the ultrasonic sound velocity passing through the ice was summarized.It is found that in the temperature range from-5? to-35?,there is a negative correlation between the ice temperature of fresh water and sea ice and the ultrasonic wave velocity through them,that is,the lower the temperature,the greater the ultrasonic wave velocity.Similarly,1MHz and500 KHz ultrasonic attenuation of fresh water ice and sea ice with salinity ranging from 0.9‰to 6‰ were measured.It was found that in the temperature range from-5? to-35?,1MHz ultrasonic attenuation was greater than 500 KHz ultrasonic attenuation,and there was a positive correlation between temperature and attenuation.The lower the temperature,the smaller the ultrasonic attenuation.In addition,through the correlation analysis of the density of sea ice and the sound velocity and attenuation through the ice,it is found that there is a certain correlation between the density of sea ice and the attenuation and sound velocity of sea ice,the greater the density,the smaller the wave velocity and the greater the attenuation.Based on the correlation between the density of fresh water ice and sea ice of different temperature and salinity and the ultrasonic attenuation and sound velocity through the density of sea ice,a method of inversion of sea ice density was proposed,and an automatic monitoring system of sea ice density for polar monitoring was designed.