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Abstract The Makassar Strait throughflow (MST) constitutes a significant component of the Indonesian throughflow (ITF) and plays a pivotal role in the interbasin exchange between the Indian and Pacific Oceans. While previous studies have suggested that the buoyancy forcing plays a role in influencing the seasonality of the MST, the quantitative contribution of salinity effect on MST seasonality remains unclear. Here we use the measurements from the Monitoring ITF program and the Global Ocean Physics Reanalysis product to investigate the seasonality of MST and quantify the impact of the salinity effect. We find that the halosteric variability due to the salinity effect contributes to approximately (69.6 ± 11.7) % of the total seasonal variability of surface dynamic height gradient along the Makassar Strait, and dominates the seasonality of the upper layer MST. The primary drivers for freshwater forcing are horizontal advection through the Karimata Strait and precipitation in the Java Sea.
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Freshwater Contributions to Decadal Variability of the Indonesian Throughflow
Abstract The Makassar Strait, the main passageway of the Indonesian Throughflow (ITF), is an important component of Indo‐Pacific climate through its inter‐basin redistribution of heat and freshwater. Observational studies suggest that wind‐driven freshwater advection from the marginal seas into the Makassar Strait modulates the strait's surface transport. However, direct observations are too short (<15 years) to resolve variability on decadal timescales. Here we use a series of global ocean simulations to assess the advected freshwater contributions to ITF transport across a range of timescales. The simulated seasonal and interannual freshwater dynamics are consistent with previous studies. On decadal timescales, we find that wind‐driven advection of South China Sea (SCS) waters into the Makassar Strait modulates upper‐ocean ITF transport. Atmospheric circulation changes associated with Pacific decadal variability appear to drive this mechanism via Pacific lower‐latitude western boundary current interactions that affect the SCS circulation.
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- PAR ID:
- 10435618
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 50
- Issue:
- 14
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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