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Earth Institute Research Projects

Monitoring the Indonesian Throughflow in Makassar Strait

Lead PI: Professor Arnold L. Gordon , Mr. Bruce A. Huber

Unit Affiliation: Ocean & Climate Physics, Lamont-Doherty Earth Observatory (LDEO)

July 2008 - June 2014
Inactive
Asia ; Southeast Asia
Project Type: Research

DESCRIPTION: Moorings deployed earlier in the Makassar Strait will be maintained to continue to measure throughflow, temperature, velocity, and salinity.

OUTCOMES: The Makassar Strait throughflow of ~12 - 13 Sv, representing ~77% of the total Indonesian Throughflow, displays fluctuations over a broad range of time scales, from intraseasonal, to seasonal (monsoonal) and interannual scales. We now have 13.3 years of Makassar throughflow observations: November 1996 - early July 1998; January 2004 - August 2011; August 2013 - August 2017. Strong southward transport is evident during boreal summer, modulated by an ENSO interannual signal, with weaker southward flow and a deeper subsurface velocity maximum (V-max) during El Niño; stronger southward flow with a shallower V-max during La Niña. Accordingly, the southward heat flux, a product of the along-channel current and temperature profiles, is significantly larger in summer and slightly larger during La Niña. The southward flow relaxed in 2014 and more so in 2015/16, similar though not as extreme as during the strong El Niño event of 1997. In 2017 the throughflow increased to ~20 Sv. Since 2016 the deep layer, 300-760 m southward transport increases, almost doubling to ~7.5 Sv. From mid 2016 into early 2017 the transport above 300 m and below 300 m are about equal, whereas previously the ratio was about 2.7:1. Near zero or northward flow occurs in the upper 100 m during boreal winter, albeit with interannual variability. Particularly strong winter reversals were observed in 2014/15 and 2016/17, the latter being the strongest winter reversal revealed in the entire Makassar time series.

SPONSOR:

National Oceanic & Atmospheric Administration/Department of Commerce

FUNDED AMOUNT:

$1,256,278

COLUMBIA UNIVERSITY COLLABORATORS:

Cooperative Institute for Climate Applications and Research

KEYWORDS

sea surface temperature el nino southern oscillation (enso) indonesian throughflow indian ocean dipole monsoon oceans climate moorings

THEMES

Modeling and Adapting to Future Climate