Analysis of underwater acoustic and electric noise in the port of Gothenburg

In this paper we study some of the underwater background noise properties in the port of Gothenburg. The analysis includes both electric and acoustic noise. We investigate the dynamic range of the absolute noise power as well as its temporal variations. Furthermore, we study the spectral variations of the low-frequency noise power. Stationarity and normality tests are applied in order to quantify the amount of transients and temporal variations in the data. We find that the properties of the acoustic and electric fields are very different. The temporal variability is larger for the acoustic data. The local shipping noise is the most important acoustic source, while the wind is less important. Shipping also give rise to the highest recorded levels in the electric field noise, but due to the short detection ranges, compared with acoustics, only ships passing nearby the sensors will contribute to the background.