Modeling and energetics of tidally generated wave trains in the Lombok Strait: Impact of the Indonesian Throughflow

Abstract

[1] This study investigates the possible impact of the Indonesian Throughflow (ITF) on tidally generated internal waves in Lombok Strait and examines the energetics of these disturbances. Using a two‐dimensional nonhydrostatic numerical model which takes into account the variable width of the strait region, two main experiments have been performed, one without and one with an idealized ITF component in the upper layer flowing southward toward the Indian Ocean. These correspond to conditions in boreal winter and summer, respectively. Both experiments show trains of internal solitary‐like gravity waves (ISWs). Overall, ISWs are more numerous on the north side of the sill where the narrower channel in effect amplifies the disturbances. In both experiments about 3.9 GW of energy is injected into barotropic and baroclinic tidal currents, of which about 2.6 GW is radiated away by internal gravity waves. The ITF regulates the way that the radiated energy is partitioned between the two sides of the sill. Without the ITF (boreal winter), the northward radiated energy flux is greater in magnitude than that radiated to the south. However, when the ITF is present (boreal summer), the northward radiated energy flux is smaller in magnitude than that radiated to the south. This result is obtained by diagnosing the flux of the Montgomery potential which can take into account the effect of finite amplitude waves and also offers a simple and robust energy diagnosis in the presence of time mean flows.