1281 / 2019-08-08 19:27:42

Energetics of Eddy-Mean Flow Interactions in the Amery Ice Shelf Cavity

15、冰冻圈科学 > 专题6：海-冰-气相互作用的物理过程和机制

The dynamic processes for the ocean circulation in the sub-ice-shelf cavity of the Amery Ice Shelf (AIS) are studied quantitatively through a Lorenz energy cycle approach by using the outputs of an eddy-resolving coupled regional ocean-sea ice-ice shelf model. Over the entire sub-ice-shelf cavity, mean available potential energy (MAPE) is the largest energy reservoir (112 TJ), followed by the mean kinetic energy (MKE, 70 TJ) and eddy available potential energy (EAPE, 10 TJ). The eddy kinetic energy (EKE) is the smallest pool (5.5 TJ), which is roughly 8% of the MKE, indicating significantly suppressed eddy activities in the sub-ice-shelf cavity. The total generation rate of available potential energy is about 1.0 GW, almost all of which is generated by freshwater forcing induced by basal melting, i.e., the so-called “Ice-Pump” mechanism. The energy generated by Ice-Pump is mainly dissipated by the ocean-ice shelf drag stress and ocean-bottom drag stress, amounting to 0.3 GW and 0.2 GW, respectively. The EKE is generated through two pathways: the barotropic pathway (0.03 GW) and the baroclinic pathway (0.2 GW). In addition to directly supplying the EAPE through the baroclinic pathway (0.2 GW), MAPE also provides 0.5 GW of power to the MKE to facilitate the barotropic pathway.