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Makassar Strait Throughflow, 2004-2017
Prof Arnold L. Gordon
Makassar Strait Throughflow, 2004-2017Event date: 28 August 2018 - 4:00pm to 5:00pm
Event type: Seminar
Venue: ASE 3D Viz Laboratory Room (N2-B1c-16c)
Speaker: Prof Arnold L. Gordon
About the speaker:
My research is directed at the ocean's stratification, circulation and mixing and its role in Earth's climate system. I am a field-going physical oceanographer, an observationalist. My research is directed at the ocean's stratification, circulation and mixing and its role in Earth's climate system. I study the transfer of heat and freshwater within the ocean and between the ocean, cryosphere and atmosphere. I view the ocean as a global system, with specific attention to interocean exchange and to ventilation of the deep ocean interior through sea-air-ice interaction. Comparison and extension of observational data with model results are an increasingly important part of my research. Historically much of my research deals with the Southern Ocean and South Atlantic, but research within the warmer waters of the Maritime Continent and Indian Ocean now compose most of my research program. Recently my focus is on the role of the ocean mesoscale in the transfer of heat and freshwater to compensate for net sea-air flux. I tend to go to areas that have been neglected by the research community, but have the potential of being key players in the global system.
The Makassar Strait throughflow of ~12 Sv, representing ~80% of the total ITF, displays fluctuations over a broad range of time scales, from intraseasonal (Madden Julian Oscillations, Rossby and Kelvin Waves) to seasonal and interannual (ENSO) scales. We now have 13.3 years of Makassar throughflow: November 1996 - early July 1998; January 2004 - August 2011; August 2013 - August 2017. Southward transport displays a strong seasonal signal: strongest in boreal summer, as well as interannual variability, which scales roughly to ENSO: weak southward flow with a deeper V-max during El Nino; stronger southward flow with shallower V-max during La Nina. Accordingly, the southward heat flux, a product of the along-channel current and the temperature profile, is significantly larger in summer and 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 the summer 2017 there is a return to the non-El Nino state. Since 2016 the deep layer, 300-760 m (Makassar Strait sill depth is ~680 m) southward transport increases, almost doubles to ~7.5 Sv. From mid 2016 into early 2017 the transport above 300 m and below 300 m are about equal, where they usually have a ratio of 2:1. In early 2017 the total Makassar transport increases to ‘historical’ highs, of over 20 Sv. Near zero or northward flow occurs in the upper ~100 m during boreal winter, albeit with interannual variability. Particularly strong winter reversal was observed in 2014/15 and 2016/17, the latter being the strongest winter reversal revealed in the entire Makassar time series.
Here is a statement of my research interest as it appears on https://www.ldeo.columbia.edu/user/agordonLink to shareable page