During RV Polarstern voyage PS117, under-ice observations were conducted with an instrumented Remotely Operated Vehicle (ROV) deployed directly from the ship. Collected time-stamped datastreams from the instrumented ROV include: ROV navigation data (heading, pitch, roll, position from an acoustic transponder system), under-ice video footage from the ROV camera and additional upward-looking video cameras, data from an upward-looking acoustic altimeter with integrated depth sensor (to measure the distance of the ROV to the sea-ice subsurface), under-ice hyperspectral irradiance and radiance data from two upward-looking radiometers, and time-stamped up-ward looking digital stills images to detect and quantify the abundance of herbivores at the ice-water interface. Methods for data collection are broadly consistent with methods described in detail in the referenced publication.

Sea-ice cores (0.09 m internal diameter) were sampled during Polarstern voyage PS117 to the Weddell Sea during December 2018 to January 2019. Ice core measurements include position, snow thickness, ice thickness, ice core temperature and bulk-salinity profiles, macro-nutrient concentrations as well as Chlorophyll-a pigment content. In addition on each ice station downwelling (surface) and under-ice irradiances were measured with a hyperspectral radiometer.