摘要
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 5F/F is employed. The increments of flow and thermal properties, including eddy diffusivity K7, flow velocity Vand bottom temperature Tb, 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, 6KT/KTand 6V/V, are found to be close to 0.5% and 0.75% at 5F/F=2%. This means that the small heat flux perturbation plays a negligible role in the global convective flow. However, 6Tb/ATis found to be 1.5% at 8F/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℃ with geothermal heating would have a significant effect on the physical environments within the benthic boundary layer.
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 5F/F is employed. The increments of flow and thermal properties, including eddy diffusivity K7, flow velocity Vand bottom temperature Tb, 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, 6KT/KTand 6V/V, are found to be close to 0.5% and 0.75% at 5F/F=2%. This means that the small heat flux perturbation plays a negligible role in the global convective flow. However, 6Tb/ATis found to be 1.5% at 8F/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℃ with geothermal heating would have a significant effect on the physical environments within the benthic boundary layer.
基金
The National Natural Science Foundation(NSF)of China under contract Nos 41176027 and 11072253
the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA11030302
the State Key Laboratory of Tropical Oceanography(LTO)grant,South China Sea Institute of Oceanography,Chinese Academy of Sciences,under contract No.LTOZZ1304
