Interannual to Decadal Response of Makassar Strait Throughflow Vertical Profile to Indo-Pacific Forcing

Mingting Li1, Arnold L Gordon2, Laura K. Gruenburg2, Jun Wei1 and Song Yang1, (1)Sun Yat-sen University, School of Atmospheric Sciences, Guangzhou, China, (2)Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY, United States
The vertical structure of Indonesian Throughflow modulates the Indo-Pacific Ocean freshwater and heat content. The transport of Pacific inflow and Indian outflow sections, calculated from GODAS data spanning 1980-2017, which agree with the 2004-2017 observed Makassar Strait throughflow, is used to investigate the interannual to decadal response of the Makassar Strait throughflow vertical profile to Indo-Pacific forcing. The variability of the transport within the upper and sub-thermocline layers (above and below 300 m, respectively) display differ responses to climate indices. The upper 300 m layer inflow responds to ENSO signal with almost no lag (5 months for outflow), while the sub-thermocline layer (300-760 m) is much more related to decadal climate mode. The sub-thermocline layer of Makassar Strait throughflow, which is drawn from South Pacific Ocean, increased after extreme El Nino events, was linked to stronger South Equatoral Current (SEC) induced by enhanced South Pacific trade winds. Also, it is highly correlated with the IPO index with about 7 (outflow) and 13 (inflow) months lag and has significant long-term trend which is following PDO and IPO index change.