The Nansen Legacy cruise Q1 (Q1: 1st quarter of the year) was part of the seasonal investigation of the northern Barents Sea and adjacent Arctic Basin. The cruise was conducted in March 2021, and focused on comparing the physical, chemical and biological conditions along the Nansen Legacy main transect in open waters and within the sea ice. The cruise addressed objectives of the work packages ‘Physical drivers’ (Research Foci 1), ‘Human impact’ (Research Foci 2) and ‘The living Barents Sea’ (Research Foci 3).

In total, seven process stations (P1, P2, P3, P4, P5, P6 and P7) were conducted. The station P1 was the only open water station, all other stations were in ice covered waters at the shelf, on the slope and in the deep basin. The area was dominated by about half meter thick first year ice with the thinnest ice in the south and around the Atlantic inflow in the area of P6 and P7. The ice and snow thickness were measured and observed at different scales using an electrodynamic GEM-2 device and a Magna-probe within a few hundred meters of the ship. For mapping of the regional scale of ice thickness a small drone as well as a helicopter-carried EM-bird were used. One drifter buoy and one ice mass balance buoy.

Each process station lasted more than a 24-hour period (except for P3) to allow full daily cycle process measurements (i.e. rates), in addition to extensive biodiversity- and abundance sampling of microbial, plankton and benthic communities. Samples for trophic interaction, ecotoxicology and ocean acidification studies were also collected. Between process stations, CTD depth profiles were taken for higher resolution of the physical environment and water chemistry. Acoustic survey, ADCP, pCO2, GNSS recordings and radiosonde launches (weather balloons) were conducted throughout the cruise.