Study On The Correlation Between Very Low Frequency Ocean Ambient Noise And Wind Vector

Some studies have found that the nonlinear interaction of surface waves caused by the wind on the sea surface can produce pressure on the submarine that does not decay exponentially with the depth,and this pressure will produce seafloor microseisms,thus can produce very low frequency ocean ambient noise.In this paper,the ocean ambient noise data received by two sets of CTBTO hydrophone triplets located on both sides of the northern and southern Wake Island in 2017 and surface wind data from NOAA are processed and analyzed.Also,based on the analysis results,the correlation between the ocean ambient noise level in very low frequency and the wind speed is proved.This paper mainly analyzes the ocean ambient noise data received by CTBTO hydrophone triplets in the following aspects:1.Firstly,the saturation of the very low frequency ocean ambient noise is observed.At 1-4Hz,it is found that the ocean ambient noise level increases with the increase of wind speed and reaches the saturation state at 4Hz,its spectrum slope is about-21 d B/octave,which indicates that the ocean ambient noise level received by the hydrophone at 1-4Hz is dominated by the ocean ambient noise generated by the nonlinear interaction of surface waves.2.Secondly,the correlation between the ocean ambient noise level in 1-100 Hz and the wind speed is studied,and the calculation results show that there is a correlation between the ocean ambient noise level at 1-3Hz and the wind speed in Wake Island in2017,and there is almost no correlation between the ocean ambient noise level at4-100 Hz and the wind speed,and the correlation coefficient reaches the maximum at2 Hz.At this frequency,the correlation coefficient between the ocean ambient noise level received by the northern No.1 hydrophone of Wake Island and the wind speed is about 0.67,and the correlation coefficient between the ocean ambient noise level received by the southern No.1 hydrophone of Wake Island and the wind speed is about 0.73.3.Then,the correlation between the ocean ambient noise level in very low frequency and the wind direction is also studied.From the generation mechanism of the standing wave,it can be seen that the change of the wind direction is the key factor to produce the ocean ambient noise in very low frequency.However,from the relationship between the ocean ambient noise in very low frequency and each wind direction range,it can be found that the correlation coefficients of the six hydrophones in all wind direction ranges are not clearly different,Therefore,it is concluded that there is no correlation between the ocean ambient noise in very low frequency and the wind direction in a specific range.4.Finally,according to the formation mechanism of standing wave,the data set of 2Hz ocean ambient noise level and wind speed at Wake Island in 2017 were screened.The function fitting curves of the six hydrophones were basically consistent,and the correlation coefficient was as high as 0.99.