Design And Application Of Ice-ocean Interface Acoustic Monitoring System

This project is an ice-ocean interface acoustic monitoring system designed for the observation of Arctic sea ice and shallow surface ocean environment under the auspices of the Ministry of Science and Technology's key research and development program "Observation and Analysis of Acoustic Characteristics of Shallow Surface Subsurface Ice in Key Polar Regions"(No.2018YFC1405902).Since the 20 th century,great changes have taken place in the global climate.Changes in the Earth's poles have had a significant impact on climate change.In April 2012,the report of the British Meteorological Office showed that the global average temperature has increased by 0.75°C since 1900,and the increase in the Arctic region has reached 2 to 3 times of the global average temperature.Sea ice is an important indicator of global climate change.The sea ice extent in the Arctic Ocean region shows a significant decreasing trend no matter in winter or summer.The rapid disappearance of sea ice in the Arctic Ocean region is reflected in many perspectives,such as the increase in ice occupancy rate in one year,the decrease in sea ice thickness,the decrease in the proportion of multi-year ice and the increase in melting pools.Therefore,in recent years,the in-situ observation data of automatic monitoring equipment such as ice-based buoys,sea ice drift buoys and meteorological observation stations deployed in the Arctic have been greatly applied research.At present,the following types of ice-based buoys are used domestic and overseas.IMB sea ice mass balance buoy,equipped with external observation equipment such as sea ice temperature chain,air temperature and barometric pressure sensor,is used for long-term and real-time observation of sea ice mass balance changes.The M-CAD polar buoy is an economical sea ice buoy that provides environmental meteorological data information in real time,it can carry meteorological observation and upper ocean observation sensors,and can obtain basic meteorological elements such as air temperature,wind speed and wind direction,and upper ocean physical parameters such as seawater temperature and conductivity.ICE BEACON buoys can be used to monitor sea ice drift trajectory,atmospheric data,sea ice and air temperature data,and can collect seawater temperature,salinity and depth data through temperature andsalt tester in seawater.As mentioned above,the commonly used polar observation equipment has some defects,has not yet carried out observation data of the Arctic ocean sound field environment.And also lacks the acquisition of acoustic characteristics data of shallow surface under ice.In view of the problems mentioned above,according to the design requirements and research content,this paper designs and develops an ice-sea interface acoustic monitoring system by analyzing the environmental factors in the Arctic site and the research and development status of polar equipment at domestic and overseas,which integrates multiple sensors such as temperature and humidity,atmospheric pressure,CT,temperature chain and hydrophone.Based on the design of the hardware circuit system,all-weather comprehensive observation of each observation module is realized through the preparation of the program.For continuous observation in unattended state,low-power electronic components,low-power hardware circuits and load power control strategies were used to extend the duration of the monitoring system.By designing a scheme for extracting acoustic feature information of shallow surface under ice,the observation of the Arctic ocean sound field environment is completed.Through Java language and SQL database to design a remote monitoring platform,real-time in-situ data reception and real-time monitoring of system working status are realized.Therefore,the development of the ice-sea interface acoustic monitoring system has been basically completed,and the observation of the Arctic sea ice changes and the ocean sound field environment has been realized.The polar acoustic monitoring system adopts a modular design scheme,which including meteorological elements,sea ice temperature profiles,shallow surface temperature and salt profiles,acoustic characteristics and other observation modules,communication modules,power supply modules,GPS modules and other functional parts,which can complete the continuous observation of the ice weather,sea ice physics,shallow surface acoustic properties and hydrological profile parameters.According to the sampling strategy of the system design and the Iridium communication strategy,the in-situ observation data collection of each observation module is completed,and the big data transmission task is realized through the wireless communication module.The design of the acoustic feature information extraction scheme is the corepart of the entire monitoring system,including the feature information extraction of noise vector fields and burst sound field events.In the observation of burst sound field events,the burst sound field event detection algorithm is applied to the sound field data collected by the system,which can distinguish the noise sound field and the burst sound field events,and extract the characteristics and azimuth information through the sound pressure and vibration velocity signals.In the noise vector field observation,according to the feature information extraction algorithm,the acoustic pressure and vibration speed signal calculation are used to obtain the cross-power spectrum,average power and other acoustic feature information.So it is necessary to obtain the sound field environment observation data of the shallow surface under ice.After the development of the prototype of the acoustic monitoring system,the system was tested in the field.According to a large number of experiments such as low-temperature performance and functional testing in the laboratory,it was able to verify the feasibility of the monitoring system and the stability of the data acquisition module.Through the later processing and analysis of the experimental data,an optimization plan for the monitoring system was proposed to ensure the accuracy and transmission rate of the in-situ observation data,which laid a good foundation for the future deployment in the central area of the Arctic.