Wind-Generated Characteristics of Ambient Noise in Southeastern Indian Ocean Based on Underwater Glider Observation

Based on the ambient noise data measured by Petrel underwater glider and sea surface wind speed reanalysis data in the southeastern Indian Ocean, the time-frequency characteristics of ambient noise from 4 to 20 kHz in this sea area are analyzed. It is verified that glider depth does not significantly affect the wind-related characteristics of ambient noise; the correlation coefficient between noise spectrum level and wind speed is quantitatively calculated; the linear function relationship between the noise spectrum level of each center frequency and the wind speed is obtained by least square fitting. The results show that: in the frequency band range less than 4 kHz, the correlation coefficient is below 0.2 due to the interference of the conductivity-temperature-depth (CTD) pump noise; in the frequency band greater than 4 kHz, the ambient noise spectrum level has a strong consistency with the variation trend of the sea surface wind speed, and the correlation coefficient is about 0.8 in 6-10 kHz. In the fequency range of 5-20 kHz, the fitting of noise spectrum level and wind speed have a linear function relationship, and as the center frequency increases, the average octaveband loss is about 5 dB; at 10 kHz, the fitting slope is the largest, the noise spectral levels are most sensitive to changes in sea surface wind speed.