Under-ice current and turbulence measurements at Ice Ridge Observatory during MOSAiC from 2x Nortek Signature1000 Acoustic Doppler profilers

Two Nortek Signature1000 acoustic Doppler current profilers (SN 100098 & SN 101048) were deployed as part of the Sea Ice Ridge Observatory (also called Fort Ridge) in the Arctic Ocean during the 2nd leg of the MOSAiC ice drift expedition in February 2020. The ADCPs are autonomous instruments that measured ice-relative horizontal and vertical ocean currents and turbulence in the upper ~20 m of the water column. The instruments were deployed under the ice, pointing downward on either side of a large ice ridge. In addition to currents, temperature, pressure, tilt, and compass direction were measured. Both instruments were eventually lost due to ice rafting, resulting in one time series between January 3rd and May 6th2020 and one between January 3rd and February 21st, 2020. Here we describe the instrument hardware, setup, and processing that resulted in the final data set. The instruments were deployed as part of the project Ridges - Safe HAVens for ice-associated Flora and Fauna in a Seasonally ice-covered Arctic OCean (HAVOC), funded by the Research Council of Norway, project number: 280292