Passive acoustic monitoring of ocean weather patterns

Ambient underwater noise can act as markers of weather patterns and human effects; it can also significantly affect sonar performance. Acoustic measurements of ambient noise were conducted in Kongsfjorden, Svalbard, in summer 2007. They were taken with a broadband hydrophone (100 Hz - 48 kHz effective bandwidth), deployed ∼9.5-m deep at regular intervals from the mouth of the fjord toward the glaciers at its inner end. These measurements include ambient noise from wind and small waves, light rain, large ships, marine mammals and different types of freshwater growlers and bergy bits. Principal Component Analysis (PCA) of the frequency variations, averaged over 1-kHz bands, confirms and extends other studies in different environments. PCA results clearly distinguish weather patterns, the presence of icebergs and other contributions to ambient noise underwater. Laboratory experiments complement these observations and their interpretation. These field measurements are, to our knowledge, the first noise recordings taken in this environmentally significant region of the Arctic. They provide a first dataset on which to base analyses of the area's evolution with ocean weather patterns, climate change and anthropogenic activities.