Estimation of rainfall contribution to ocean ambient noise in Northeastern Taiwan Sea

Ocean ambient noise data were collected by underwater MACHO (MArine Cable Hosted Observatory) system, deployed by Central Weather Bureau, at northeastern sea of Taiwan from October of 2011 to March of 2012. With most rainfall of Taiwan in the area of measurement, the rain-generated underwater noise was studied in an attempt to estimate rainfall contribution by the correlation analysis with the acoustic data. Due to the intermittent nature of rain fall occurrence, significant rainfall events with extended period were extracted from the weather data measured at nearest Su-ao weather station, and then patched together to form a rainfall intensity time series. Linear regression between corresponding ocean ambient noise level time series of several frequencies and rainfall intensity data were performed, so the characteristic frequency for prediction can be decided. Duration of this study was divided into Fall, Winter, and Spring, then the statistics and distributions of ambient noise level at different frequencies and rainfall intensities were calculated, so that seasonal variations were also discussed.