RRS James Cook Expedition JC268. ReBELS-1. 15-30 August 2024. (National Oceanography Centre Research Expedition Report, 84).

The project ReBELS (Resolving Biological carbon Export in the Labrador Sea) is funded by the UK Natural Environmental Research Council (NERC) and aims to understand and quantify the transport of oceanic organic carbon into the deep sea and its effect on ocean carbon storage. To do so, we proposed to set up a year-long ocean observatory in the Labrador Sea using state-of-the-art autonomous observing technologies (gliders and biogeochemical ARGO floats) paired with traditional measurements of carbon flux (moored sediment trap) to understand the different contribution of particle injection pumps to the overall carbon export in the Labrador Sea. This cruise will collect all assets. JC268, is the first of three cruises which set up this year-long observatory in the Labrador Sea. The cruise comprised several goals: - Deploy a mooring, containing 3 sediment traps, physical and bio-optical sensors, acoustic doppler current profilers and current meters and 2 FluxCams (custom-made camera system aiming at characterising the sinking speed of particles). - Deploy 2 BGC-Argo floats, one of them contributing to the BGC-Argo Network and a second one, the ReBELS float, fitted with specialty sensors to characterise particles (UVP6), the upper ocean phytoplankton community (hyperspectral radiometer) and estimate carbon flux (optical sediment trap, transmissometer). - Conduct physical and biogeochemical measurements to validate/calibrate the deployed assets and create a baseline and understanding of the physical and biogeochemical drivers of carbon export. - Conduct opportunistic measurements at the GOSNAP mooring lines around Greenland to validate sensor measurements, in particular oxygen sensors recently fitted on the array. The cruise consisted of 4 main stations: 1. CTD line off Nuuk; 2. mooring; 3. Floats deployment; 4.GOSNAP mooring array.