Two-dimensional and three-dimensional probability density functions of underwater noise near the port of Vladivostok

The objectives are estimates of joint two-dimensional and joint three-dimensional probability density functions (2-D and 3-D PDFs) of two and three distant in time instantaneous sample values of underwater noise pressure near the port of Vladivostok in a frequency band of 0.3—6 kHz. The time distance between the instantaneous sample values are equal to the time interval between the main maximum and second zero of the time correlation function of the noise. The noise was registered by an omnidirectional hydrophone that was mounted on the seabed at a 20 m depth, 100 m away from the shore. The PDFs estimations were carried out by using the 2-D and 3-D histograms. Time intervals to 60 s were used for accumulation of the instantaneous sample values and estimation of the PDFs. The graphs of 2-D PDF and slice of the 3-D PDF are presented for the cases when the distance between the hydrophone and nearest vessels was over 2 miles. Checking for normality of the one- and two-dimensional PDFs by using the Chi-square test with significance level 0.05 has not produced lasting positive results.