The Indonesian Throughflow response to Indo-Pacific climate variability

Maximum correlation between SLA and INSTANT transport
TitleThe Indonesian Throughflow response to Indo-Pacific climate variability
Publication TypeJournal Article
Year of Publication2014
AuthorsSprintall J, Revelard A.
JournalJournal of Geophysical Research-Oceans
Date Published2014/02
Type of ArticleArticle
ISBN Number2169-9275
Accession NumberWOS:000336261200032
Keywordscirculation; el-nino; enso; interannual variability; model; region; strait; transport; tropical indian-ocean; vertical structure

The Indonesian Throughflow (ITF) is the only open pathway for interocean exchange between the Pacific and Indian Ocean basins at tropical latitudes. A proxy time series of ITF transport variability is developed using remotely sensed altimeter data. The focus is on the three outflow passages of Lombok, Ombai, and Timor that collectively transport the entire ITF into the Indian Ocean, and where direct velocity measurements are available to help ground-truth the transport algorithm. The resulting 18 year proxy time series shows strong interannual ITF variability. Significant trends of increased transport are found in the upper layer of Lombok Strait, and over the full depth in Timor Passage that are likely related to enhanced Pacific trade winds since the early 1990s. The partitioning of the total ITF transport through each of the major outflow passage varies according to the phase of the Indian Ocean Dipole (IOD) or El Nino-Southern Oscillation (ENSO). In general, Pacific ENSO variability is strongest in Timor Passage, most likely through the influence of planetary waves transmitted from the Pacific along the Northwest Australian shelf pathway. Somewhat surprisingly, concurrent El Nino and positive IOD episodes consistently show contradictory results from those composites constructed for purely El Nino episodes. This is particularly evident in Lombok and Ombai Straits, but also at depth in Timor Passage. This suggests that Indian Ocean dynamics likely win out over Pacific Ocean dynamics in gating the transport through the outflow passages during concurrent ENSO and IOD events.

Short TitleJ Geophys Res-Oceans

This research begins to provide a deeper understanding of the gating dynamics of the Indonesian Throughflow, the climate-shaping process that transfers varying amounts of heat, salinity and water mass from the western Pacific into the Indian Ocean. The nature of the water carried through the Lombok, Ombai, and Timor passages was found to be influenced to varying degrees by the phase of the Indian Ocean Dipole (IOD) or El NiƱo-Southern Oscillation (ENSO). To improve understanding of these climate dynamics, the authors recommend a longer time-series of data as well as full-depth measurements across the passages.

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