Hydroacoustic backscatter recorded by buoy 2020AZFP1 in the central Arctic Ocean during Sep 2020 - May 2021

This dataset contains hydroacoustic measurements collected by an autonomous ice-tethered bio-physical observatory during its drift across the Central Arctic Ocean from the end of MOSAiC in September 2020 to the next spring in May 2021. The measurements were performed by an Acoustic Zooplankton and Fish Profiler (AZFP, ASL) with factory calibrations. Data are provided as volume backscatter (Sv, in dB re 1 m⁻¹). We provide data for the frequencies 67, 125, 200 and 455 kHz. These files contain the quality-controlled raw data. The data were cleaned, processed and analysed in the paper Sea-ice decline makes zooplankton stay deeper for longer by Flores, Veyssiere et al. (submitted to Nature Cliimate Change), which contains a detailed description of the instrument and the measurement settings. The format can be readily ingested in the hydroacoustic data processing application EchoView.