Mingting Li, Arnold L. Gordon, Laura K. Gruenburg, Jun Wei, Song Yang

Published in Geophysical Research Letter, April 2020

The Indonesian Throughflow (ITF) inflow through the Sulawesi, Maluku, and Halmahera Seas and the ITF outflow into the eastern tropical Indian Ocean, based on reanalysis and model data, are used to investigate the interannual to decadal response of the ITF vertical profile to Indo‐Pacific forcing. The thermocline (upper 300 m) inflow, driven by the North Pacific Ocean, negatively responds to El Niño‐Southern Oscillation (ENSO) with almost no lag; while the thermocline outflow lags by 5–7 months. The sub‐thermocline (300–760 m) inflow, which is influenced by both the North and South Pacific, positively responds to ENSO and Interdecadal Pacific Oscillation (IPO) indices with 13 months lag and displays a long‐term trend tracking the IPO index. Influenced by eastern Indian Ocean variations, the sub‐thermocline outflow positively correlates with the ENSO and IPO indices with about 7–9 months lag, a shorter lag time than the inflow.

Fig.1 (a) Topography of Indonesian Seas, with the ITF pathways presented by the red arrows, and mooring site marked by black X in the Makassar Strait. The dash red arrow shows the pathway of Pacific water into Sulawesi Sea in the sub‐thermocline layer. The solid black and green lines indicate the positions of the inflow and outflow sections, respectively. Section IX1 is marked with red scatter. (b)13‐month running mean inflow transport anomaly at thermocline layer calculated from GODAS (black line), SODA3 (blue line), OFES (green line) data sets, and the ensemble mean of these three datasets (red line). (c) Same as (b) but for sub‐thermocline layer. (d and e) Thermocline and sub‐thermocline transport anomalies across the outflow section. Positive values denote more southward or westward transport.

Li, M., Gordon, A. L., Gruenburg, L. K., Wei, J., & Yang, S. (2020). Interannual to decadal response of the Indonesian throughflow vertical profile to Indo‐Pacific forcing. Geophysical Research Letters, 47, e2020GL087679. https://doi.org/10 .1029/2020GL087679.