Laboratory simulation of the influence of geothermal heating on the interior ocean

Abstract

This study, using laboratory experiments and scaling analysis, evaluates the influence of geothermal heating on global oceanic circulation. Upon a well-developed large-scale convective flow, an additional heat flux perturbation delta F/F is employed. The increments of flow and thermal properties, including eddy diffusivity K-T, flow velocity V and bottom temperature T-b, are found to be independent of the applied heat flux F. Together with the scaling analysis of convective flow at different configurations, where the flow is thermally driven in the relatively low or extremely high turbulent thermal convections or the horizontal convection, the variances of flow properties, delta K-T/K-T KT and delta V/V, are found to be close to 0.5% and 0.75% at delta F/F=2%. This means that the small heat flux perturbation plays a negligible role in the global convective flow. However, delta T-b/Delta T is found to be 1.5% at delta F/F=2%, which would have a significant effect in the local region. The results might provide a clue to understanding the influence of geothermal heating on global oceanic circulation. It is expected that geothermal heating will contribute less than 1% in turbulent mixing and volume flux to global oceanic circulation, so its influence can be negligible in this situation. However, when it comes to the local environment, the influence of geothermal heating cannot be ignored. For example, temperature increases of about 0.5 degrees C with geothermal heating would have a significant effect on the physical environments within the benthic boundary layer.