2019-20 Honours project - Characterising the variability of the Indonesian Throughflow in ocean models

The Indonesian Throughflow (ITF) is connects the Pacific Ocean and the Indian Ocean in the tropics. The ITF plays an essential role in ocean circulation and regional climate: it hosts strong mixing that can change water-mass properties, influences the sea surface temperature in both oceans and affects the global ocean volume and heat transports. The ITF transports water properties across Indonesian Seas characterized by complex topography with most of the water entering through two main inflow straits, Makassar and Lifamatola straits, and exiting into the Indian Ocean through three main outflow straits, Ombai, Lombok and Timor straits.

The ITF shows variabilities on different time scales, including decadal, interannual, seasonal and intra-seasonal. The ITF variability on intra-seasonal time scales is driven by remotely generated Kelvin and Rossby waves that propagate into the Indonesian Seas from the Indian Ocean and Pacific Ocean. This project focuses on the variability driven by Kelvin waves that propagate into Indonesian seas through three main outflow straits (Ombai, Lombok and Timor). We use a global ocean model and a high-resolution regional ITF model to characterize these variabilities at different depths and in different straits. We also use the mooring observations from the INSTANT program to validate the ocean models.