Long-Term Mean Mass, Heat and Nutrient Flux Through the Indonesian Seas, Based on the Tritium Inventory in the Pacific and Indian Oceans

The Indonesian Throughflow (ITF), the only oceanic tropical pathway linking the Pacific and Indian Oceans, plays a critical role in the redistribution of heat and mass, affecting both the regional and global climate systems. Based on the distributions and changes in the tritium inventories, and tritium budgets in and between the South Pacific and South Indian Oceans from the Geochemical Ocean Sections Study and World Ocean Circulation Experiment programs, the long-term mean water mass transport of the ITF is estimated. The total throughflow of the ITF is estimated as 16.2 ± 3.5 Sv. The North Pacific contributes 14.1 ± 2.7 Sv to the total throughflow, of which the layers between 0–250, 250–650, and 650–1,000 m carry 7.3 ± 0.6, 5.4 ± 1.3, and 1.4 ± 3.0 Sv, respectively. Along with the water transport, the North Pacific component of the ITF transfers 0.84 ± 0.14 PW of heat into the Indian Ocean, of which almost 90% exits from the Indian Ocean at 30°S. The net nitrate flux into the photic zone associated with the ITF is 2.71 ± 2.60 mmol·m⁻²·d⁻¹ in the Indonesian Seas, ~90% of which is induced by vertical diffusion.