Seasonal statistics of experimental oceanic noise observed in the deep region of the South China Sea

Seasonal statistics on underwater ambient noise in the deep area of the South China Sea were analyzed on the basis of the experimental observation data. A parameterized fitting model was utilized to determine the noise spectrum levels at different wind speed (WS) conditions and was compared with the Wenz curves, which are consistent with the NLs in winter at WS higher than wind force 3. The correlation coefficient between NLs and WS or significant wave height (SWH) were described according to the reanalysis database. In addition, the relationship between NLs and WS or SWH could be modeled by using four-parameter logarithm model. Empirical expression between NLs and spectrum levels at 1 kHz was corrected in SCS. Weibull and Burr distributions were applied for the evaluation of PDF of NLs in summer and winter. Low-frequency NLs were dominated by distant shipping noise and their PDF satisfied the Burr distribution. High-frequency NLs were dominated by breaking waves or wind agitation and their PDF satisfied the Burr distribution and Gaussian distributions simultaneously. Finally, frequency correlation matrices (FCM) were utilized in analyzing the noise sources mechanism, and discussing the reason for the statistical difference of NLs in summer and winter. The NL statistical differences was induced by noise source mechanism primarily.