Cabled acoustic observatory

Continuous acoustic measurements were made at a ~370 m deep location in Masfjorden, Norway from 2010-10-07 to 2011-08-15. Submerged transceivers were kept in pressure-proof casings and cabled to shore for power and transmittance of digitized signals to laptop computers, where data were stored in raw format. Data are available for most of the registration period, apart for short-term periods with intermittent power failures. The acoustic set-up consisted of 3 upward looking SIMRAD EK60 split beam echo sounders (7.1° beam widths), mounted at the bottom (38 kHz; ~370 m) and on rigs anchored to the bottom, floating at ~250 m (120 kHz) and ~90 m (200 kHz). The echo sounders were calibrated at the surface using standard methods. Pulse lengths and ping rates were 128 μs and 1 to 2 pings s−1 (200 kHz), 256 μs and 1 to 2 pings s−1 (120 kHz), and 512 μs and 1 ping s−1 (38 kHz), respectively.