Hydrothermal Plumes in the Arctic Ocean -The Aurora Site at Gakkel Ridge

Hydrothermal venting along mid-oceanic ridges alters deep ocean water masses around the globe. These vent systems supply geothermal heat and various biogeochemical properties to water masses close to the bottom. In the Arctic, the influence of hydrothermal venting is largely unknown, and whether it should be considered in relation to other processes that modify the highly isolated deep water masses.

We present new results from the expedition PS 137 on water masses and the flux associated with the Aurora Vent Site at the Gakkel Ridge, 82.9° N, the only system in the Arctic Ocean to have been visited twice. Utilising CTD observations including physical and biogeochemical data, we assess the dimensions of the hydrothermal plume and estimate the heat flux. A spatially restricted plume core with a horizontal extent of less than 1000 m but a large rise height of 1200 m above the seafloor results in an estimated heat flux of approximately 180 MW.

A comparison with the observations made in 2014 reveals that the plume exhibits a comparable height, suggesting a constant heat flux over the period. Furthermore, the combined helium isotope measurements indicate that water masses on a larger scale at the Gakkel Ridge are also influenced by hydrothermal systems.