Methodology:

Data were collected using a Simrad EK80 echosounder at 18, 38, 120, 200 and 333 kHz. The EK80 was calibrated on 04/01/2023 in Rosita Harbour, South Georgia. Standard calibration procedures were used and all frequencies, except the 333 kHz, were calibrated using a 38.1 mm tungsten carbide sphere. The 333 kHz was not calibrated, as previous attempts using a 20 mm sphere were unsuccessful due to the depths the sphere is at on Discovery versus the usable range. All calibrations were successful and uploaded to the transducers on completion with the exception of the 200 kHz transducer which had an RMS (root mean square) of 0.4, and the 333 kHz transducer which remains uncalibrated. The 200 kHz was reprocessed with a 1dB target window on target strength, resulting in an RMS of 0.2, which was accepted and uploaded to the system on 7/1/2023 12:21:25. More information about the calibration can be found in the Cruise Report for DY158: https://www.bodc.ac.uk/resources/inventories/cruise_inventory/reports/dy158.pdf.

The dataset comprises Simrad raw format files that have not undergone any processing or quality checking. The raw data files are stored by the Polar Data Centre (PDC) at BAS. Each .raw data file contains approximately 5 minutes of data and is approximately 100 MB in size. Each data file contains raw ping data with associated GPS fixes and date/time.

Data collection:

Data were collected using a Simrad EK80 echosounder at 18, 38, 120, 200 and 333 kHz.

Data quality:

Raw data (time, gps and acoustic) are not quality checked. The instrument was calibrated on 04/01/2023 in Rosita Harbour, South Georgia.