Since 2020, the OSNAP / CLASS robotic glider programme has focussed on maintaining observations of the slope (shelf-edge) current which transports 1-2 Sv of warm, salty water past the UK towards Norway. Conventional moorings were often lost due to fishing so a semi-permanent glider occupation has proved to be the best way of characterising the current, and filling the gap at the eastern end of the OSNAP line.

Glider occupations along the OSNAP / Ellett Array, plotted by longitude and time. Since 2020, the slope current has been monitored by weekly glider transects across the shelf edge.

Here’s a recent poster (AGU 2024) showing how the raw glider observations are incorporated into the total OSNAP transport estimate.