Research Article Open Access

The Variability of Indonesian Throughflow in Sumba Strait and Its Linkage to the Climate Events

Ahmad Bayhaqi1, Yueng-Djern Lenn2, Dewi Surinati1, Jeff Polton3, Muhamad Nur4, Corry Corvianawatie1 and Adi Purwandana1
  • 1 Research Center for Oceanography, Indonesian Institute of Sciences, Jakarta, Indonesia
  • 2 School of Ocean Sciences, Bangor University, Wales, United Kingdom
  • 3 National Oceanography Centre, Liverpool, United Kingdom
  • 4 Graduate School of Physics, Natural Science, University of Sriwijaya, Palembang, Indonesia

Abstract

As one of the Indonesian Throughflow (ITF) outflow passages, the Sumba Strait is a meeting point for the Pacific and the Indian Ocean water mass. In order to study the long-term variability of ITF flowing via Sumba Strait, this research uses observational data from the Ekspedisi WIdya Nusantara (EWIN) research cruise conducted in August 2016 to validate the altimetric geostrophic surface current by referencing the shear velocity. Stating the referenced level to 700 m, geostrophic transport is calculated using the Monthly Isopycnal/Mixed-Layer Ocean Climatology (MIMOC) data. Over the period of 1993-2016, the results demonstrate a dominant seasonal pattern for the geostrophic variability. While the total geostrophic transport shows a main westward direction towards the Indian Ocean, the Sumba Strait provides only a small portion (less than 0.1 Sv) for westward ITF geostrophic current. Intraseasonally, the maximum transport occurs during the southeast monsoon. The reversal of South Java Current (SJC), which flows with the eastward direction heading to the Savu Sea, is observed as the intrusion for westward ITF in almost every monsoon season. Despite having an unclear year to year cycle, climate mode of the Indian Ocean may have more influence on the surface geostrophic variability at the Sumba Strait. On the other hand, ocean-atmosphere coupling in the Pacific Ocean has a role in regulating geostrophic transport variation within the Sumba Strait. Using a statistical approach, the findings emphasize that the throughflow may well be impacted as well as feedback on both ENSO and IOD since there is robustness in those variables.

American Journal of Applied Sciences
Volume 16 No. 4, 2019, 118-133

DOI: https://doi.org/10.3844/ajassp.2019.118.133

Submitted On: 17 December 2018 Published On: 12 June 2019

How to Cite: Bayhaqi, A., Lenn, Y., Surinati, D., Polton, J., Nur, M., Corvianawatie, C. & Purwandana, A. (2019). The Variability of Indonesian Throughflow in Sumba Strait and Its Linkage to the Climate Events. American Journal of Applied Sciences, 16(4), 118-133. https://doi.org/10.3844/ajassp.2019.118.133

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Keywords

  • Geostrophic Current
  • Indonesian Throughflow
  • Sumba Strait
  • El Nino
  • La Nina