A remote effect of geothermal heat on the global thermohaline circulation

Abstract

The effect of the geothermal heat on the global thermohaline circulation (THC) is numerically investigated with an ocean general circulation model (OGCM) under a realistic configuration. It is known that the geothermal heat strongly intensifies meridional overturning circulations (MOCs). Although earlier studies show that the geothermal heat can produce a significant amount of gravitational potential energy (GPE), it is left to be clarified how the geothermal heat affects the intensity of MOCs in terms of energetics. This study shows that the geothermal heat in the Indo-Pacific has a remote effect on the Atlantic MOC while that in the Atlantic does not contribute to the intensity of MOC in the Indo-Pacific. This remote effect can be accounted for as a result of an interbasin transport of GPE and its energy conversion to kinetic energy (KE) that compensates additional viscous dissipation associated with the MOC enhancement. The asymmetric response of MOCs to the geothermal heat can be explained by the circulation pattern. Copyright 2009 by the American Geophysical Union.