The Nansen Legacy cruise Q4 (Q4: 4th quarter of the year) was the second of in total four seasonal cruises to the northern Barents Sea and adjacent Arctic Basin. The cruise focused on comparing the state of the physical, chemical and biological conditions along the Nansen Legacy main transect in open waters and within the sea ice, addressing objectives of the work packages ‘Physical drivers’ (Research Foci 1), ‘Human impact’ (Research Foci2), ‘The living Barents Sea’ (Research Foci 3), and ‘Technology and method development’ (Research Activity C).

In total, the cruise investigated 17 stations of the Nansen Legacy main transect along 34 E in the Northern Barents Sea and adjacent Arctic Basin from 76 to 82°N. The sampling began at the deep (>3000 m) northernmost station of the Nansen Legacy main transect, P7, and continued along the southward transect until station P1, in open water dominated by Atlantic water masses. During the expedition the Barents Sea was characterized by a relatively large sea ice cover with consolidated sea ice all the way from P7 to P2. The Polar Front was located just north of P1. All process stations were sampled (P7-P1) as well as two ice stations; one close to P7 and one close to P5. In addition to in situ sampling, on board experiments were conducted to quantify biological processes, rates and interactions that will also feed into modeling work and projections of the work package ‘The future Barents Sea’ (Research Foci 4).