A recent study led by Dr. LI Xiang from Prof. YUAN Dongliang's group in the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) found that the South Pacific Ocean plays an important role in the Great Ocean Conveyer Belt (GOCB), the route of the general thermocline circulation of the global oceans. 

Historically, understanding of the GOCB in the Indo-Pacific Ocean was built on measurements in the Makassar Strait of the Indonesian seas, showing that the majority of the Indonesian Throughflow (ITF) comes from the North Pacific Ocean. The cold deep Southern Ocean waters flow northward through the deep South Pacific Ocean and upwell in the North Pacific to the surface to supply for the mass transport of ITF.  

Due to the existence of zero wind curl lines in the South Pacific and below the Inter-Tropical Convergence Zone immediately north of the equator, the wind-driven circulation in the South Pacific was considered to be a closed gyre, playing a trivial role in the GOCB. 

In the current study, the researchers conducted time series measurements of ocean currents in the Jailolo Strait of the Halmahera Sea for the first time in history. The results showed that significant South Pacific tropical waters entered the Indonesian seas through the Halmahera Sea, and then joined the ITF to flow to the Indian Ocean.   

The mass transport through the Halmahera Sea is carried to the entrance of the Indonesian seas by the western boundary current of the South Pacific tropical gyre and must be supplied by upwelling in the South Pacific.   

The flow in the Jailolo Strait is a newly discovered branch of the ITF with a two-year mean transport of 2.44 Sv (about 100 times of Changjiang run-off). 

The study entitled "Moored Observations of Transport and Variability of Halmahera Sea Currents" was published in Journal of Physical Oceanography.