Experimental investigation of oceanic ambient noise generated by typhoon in deep ocean

Abstract

Typhoons Soulik and Nida passed by receivers during ambient noise measurement in deep ocean in WP2013 and SCS2016. When the typhoons were quite close to the receivers, the noise levels increased and exceeded 10 dB. In this study, the moment when a typhoon is closest to receivers is chosen as the breakpoint, and the measured ambient noises are divided into those before and after the typhoon. Linear regression is conducted to analyze the relationships between noise levels and the local wind speed (WS) and air pressure, significant wave height (SWH) during a typhoon period. A linear relationship occurs between noise levels and the logarithm of WS, between noise levels and the logarithm of SWH, and between noise levels and the logarithm of air pressure. The slope before a typhoon is less than that after a typhoon due to the contamination of distant noise sources. The noise levels during a typhoon period can be formulated with the local WS or SWH in deep ocean and were 5 dB less those of Wenz curves at the same wind force. It is deduced that the sea condition during typhoon period did not developed completely at the same wind force compared with that in Wenz curves.