On the coherent components of low-frequency ambient noise in the Indian Ocean.

This letter demonstrates that the dominant coherent component of low-frequency (1 Hz < f < 20 Hz) ambient noise propagating between hydrophone pairs of the same hydroacoustic station, deployed in the deep sound channel of the Indian Ocean, is directional and mainly originates from Antarctica. However, the amplitude of the peak coherent noise arrivals, obtained using a 4-month-long averaging interval, was relatively low given the small hydrophones spacing hydrophones (<2 km). Hence, extracting similar coherent arrivals between two distinct hydroacoustic stations separated instead by thousands of kilometers for noise-based acoustic thermometry purposes seems unlikely, even using a year-long averaging.