Heat Fluxes in a Glacial Fjord: The Role of Buoyancy‐Driven Circulation and Offshore Forcing

Abstract The ocean supplies large quantities of thermal energy to tidewater glaciers, but the mechanisms behind the heat delivery are not fully understood. To examine heat flux dynamics in glacial fjords, we run an 8‐year realistic numerical simulation of Milne Fiord, validated with observations. We leverage the duration and spatial resolution of the simulation to calculate ice melt, offshore density variations, average fjord temperature, and heat fluxes at different locations along‐fjord. Correlations between these quantities reveal that heat fluxes near the grounding line (<5 km) are linked to buoyancy‐driven circulation while offshore forcing is linked to heat fluxes along the remainder of the fjord. Comparison to a simulation with constant offshore boundary conditions reveals that offshore forcing enhances the exchange between the coastal shelf and the fjord, increasing glacier melt rates by 18%. Including offshore forcing into numerical and box models of glacial fjords is essential for accurate melting predictions.