Preliminary Study on the Wind-driven Ocean Ambient Noise in Chukchi Plateau

Abstract

The ice-free sea areas are increased continually in the past 20 years in Arctic, however, it’s of great significance to study the ocean ambient noise at ice-free sea area. From September 9 to October 24, 2017 (local time), the Chukchi Plateau was ice-free, and the ocean ambient noise data were recorded by an underwater signal recorder (USR) at 519.5 m depth for 3 min every 2 h. The correlation coefficients of noise spectrum level and sea surface wind speed are greater than 0.5 in frequencies from 31.5 Hz to 5 kHz. Especially, it is greater than 0.73 when the frequency is above 80 Hz. The variation law of noise spectrum levels with time is basically the same as that of wind speed. It suggests that the ocean ambient noise is significantly affected by sea surface wind and the wind-driven noise should be the main noise source during ice-free periods. The empirical probability densities and percentile distribution of noise spectrum levels from 20 Hz to 5 kHz have been given in this paper. The distribution of noise spectrum levels is relatively concentration below 160 Hz and discrete above 160 Hz. According to wind speed, different sea states are divided. The mean values of noise spectrum levels of different frequencies under different sea states are given and compared with the Knudsen’s curves. In the frequency band between 800 Hz and 5 kHz, the wind-driven noise spectrum levels decrease about 4.65 dB/octave with increasing frequency, which is slightly less than that of Wenz’s result of about 5 dB/octave.