EK80 Water Column Sonar Data Collected During DP10

Patterns in acoustically derived biological scatter through the water column was collected with multi-frequency scientific echosounders (Simrad EK80) operating at 18kHz and 38kHz following protocols developed during the NOAA NRDA DAP data collection operations. Specifically, during each cruise, transducers were installed on a rigid pole mounted to the side of the ship, and calibrated at sea for operating conditions following protocols developed during the ONSAP/DAP cruises. The dynamics of the mesopelagic scattering community were examined through the depth dependent scattering responses at both frequencies (18 and 38kHz) as well as through the difference between the mean volume backscattering strength (MVBS; in dB) at 18 kHz and 38 kHz (dMVBS(18-38)). In addition, scatterers in the upper water column (~150m) were examined by analyzing the available frequencies.