The Indonesian Throughflow plays an important role in the global ocean circulation and climate variations. Existing studies of the Indonesian Throughflow have focused on the upper thermocline currents. The mean circulation and volume budgets in the upper 1200 m of the Maluku Sea are studied using multi-year current meter measurements of four moorings in the Maluku Channel and of one synchronous mooring in the Lifamatola Passage. The measurements show that the mean current in the depth range of 60 m - 450 m is northward towards the Pacific Ocean with a mean transport of 2.07 Sv - 2.60 Sv. In the depth range of 450 m - 1200 m, a mean western boundary current (WBC) flows southward through the western Maluku Sea and connects with the southward flow in the Lifamatola Passage. The mean currents in the central-eastern Maluku Channel are found to flow northward at this depth range, suggesting an anti-clockwise western intensified gyre circulation in the middle layer of the Maluku Sea. The dynamics of the intermediate gyre circulation are explained by the potential vorticity (PV) integral constraint of a semi-enclosed basin. Budget analyses suggest that the mean transport of the intermediate WBC is 1.83 Sv - 2.25 Sv, which is balanced by three transports: (1) 0.62 Sv - 0.93 Sv southward transport into the Seram-Banda Seas through the Lifamatola Passage, (2) 0.97 Sv-1.01 Sv returning to the western Pacific Ocean through the central-eastern Maluku Channel, and (3) a residual transport surplus, suggested to upwell to the upper layer joining the northward transport into the Pacific Ocean. As the Maluku Sea is an important entrance of the AAIW inflow toward the Indian Ocean, the processes of water exchange revealed in this paper help us understand the AAIW movement in the Maluku Sea better, providing new insight for the global ocean overturn and the heat and CO2 storages associated with it.
Yin X, Yuan D*, et al. Moored observations of the currents and transports of the Maluku Sea. Journal of Physical Oceanography (ISSN:0022-3670): 2022. DOI: 10.1175/JPO-D-22-0027.1