Under-ice temperature and salinity measurements at Ice Ridge Observatory during MOSAiC from an RBR Concerto CTD

Two RBR Concerto Conductivity Temperature Depth (CTD) sensors (SN 60611 & SN 60610) 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 CTDs are autonomous instruments that measured conductivity (salinity), temperature, and pressure (depth) approximately 2-3 m below the sea ice on either side of a large ice ridge. The RBR 60610 was lost due to ice rafting before data was downloaded. The RBR 60611 was recovered in May 2020, resulting in one time series between January 3rd and May 6th2020. RBR 60611 was redeployed on May 6th but also lost due to ice rafting shortly after. Each CTD was deployed together with a Nortek Signature1000 acoustic Doppler current profiler (doi:10.1594/PANGAEA.941882), installed at a 2 m distance. 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.