ABSTRACTS

Oral Session 3 | Tuesday, October 4, 10:00–10:20 | Abstract 642

Observing the Barents Sea with bio-optical measurements

The Barents Sea and the Arctic Ocean are notoriously difficult to observe with ocean color remote sensing due to a nearly year-round cloud cover, sea-ice, and the polar night. Climate change is also radically disrupting the ocean environments in this region, which can give large-scale changes in primary production, biological carbon cycle, and higher trophic levels. Consequently, bio-optical measurements in the Arctic region are highly valuable, providing vertically resolved observations of particulate and dissolved matter including phytoplankton. Through several field campaigns in the Barents Sea and the Svalbard archipelago, an extensive set of absorption and scattering measurements has been collected using the SeaBird ac-s and spectrophotometric measurements of water samples, from the sea-surface to the ocean floor. The results show that there can be considerable spatial and seasonal variability in optical properties even below the mixed surface layer. Phytoplankton is a significant driver of the optical variability in the Barents Sea, even observed down to 200 meters, while CDOM has a comparably low contribution to absorption here. Particulate matter has a large impact on the variability close to the coast because of run-off from glaciers and rivers, but also close to the ocean floor due to sediment resuspension and formation of brine-enriched shelf waters. Our results show the high optical complexity of Arctic marine waters, and that optical measurements can be a powerful tool to observe the vertical structures of Arctic waters also beyond the reach of remote sensing.

Håkon Sandven, Norwegian Polar Institute, 0000-0002-8042-510X

Børge Hamre, University of Bergen

Hongbo Liu, University of Bergen

Mats A. Granskog, Norwegian Polar Institute