• The Impact of Geothermal Heating on Deep-Sea Circulation in the Panama Basin: An Idealised Modelling Approach

Geothermal heating is a significant but often underestimated driver of abyssal currents and water mass transformation. This study investigates how varying the location and intensity of geothermal heating affects abyssal circulation, using the Panama Basin as a case study due to its enclosed nature and active geothermal features. An idealised version of the basin was modelled using NEMO-OCE, with four scenarios: intensified basin heating (INTENBAS), uniform heating (EVENH), no heating (NOH), and realistic, localised heating (REALH). The model incorporated ridges extending to 2500 m and a narrow inflow representing the Ecuador trench.

Results show that heating distribution significantly influences circulation patterns. INTENBAS enhanced the meridional stream function and promoted stronger north-south overturning. REALH amplified zonal flow, likely due to baroclinic instabilities and localised overturning circulation. NOH exhibited minimal flow, confirming geothermal heating as a key driver of abyssal circulation in the region.

Temperature increases and cascading inflows were most notable in scenarios with localised heating. Abyssal currents contribute to the dispersal of deep-sea organisms, better understanding abyssal currents can help assess areas where larvae may settle. Larvae were predicted to settle in the north and east sides of the Panama basin due to lowered current velocities.

Meridional velocity patterns were similar across scenarios, though REALH produced stronger negative velocities at 3500 m due to dense, high-momentum trench inflow. This study underscores the crucial role of geothermal heating in shaping deep-sea circulation and offers insights into water mass movement, heat transport, and ecological connectivity in abyssal environments.