Parallel Session 1: Sougata Basak: Amplified SST variability along the Indonesian Throughflow pathways: Role of remote and local ocean dynamics

ACCESS Workshop 2025 ACCESS Workshop Day 1
1

Amplified SST variability along the Indonesian Throughflow pathways: Role of remote and local ocean dynamics

Sougata Basak


Sougata Basak (1), Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia

Maxim Nikurashin (2), Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia

Beatriz Peña-Molino (3), CSIRO Environment, Hobart, Tasmania, Australia

Bernadette Sloyan (4), CSIRO Environment, Hobart, Tasmania, Australia

Helen Phillips (5), Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia

  1. The Indonesian Seas, situated at the confluence of the tropical Western Pacific and Southeastern Indian Ocean, are the powerhouse of tropical deep atmospheric convection, featuring one of the warmest SSTs in the world ocean. With the Walker and Hadley circulations sitting above this region, even small SST changes can significantly affect Indo-Pacific atmospheric circulation and precipitation. Despite its importance our understanding of the physical mechanisms governing the SST variability remains incomplete.

  2. Using satellite observations, ARGO floats, and high-resolution (0.1°) ACCESS-OM2 model simulations forced by JRA-55 RYF and IAF, we show the importance of both local and remote ocean dynamics in modulating SST variability in this region.

  3. Monsoon wind reversals and Ekman upwelling bring cold thermocline waters to the surface, driving local SST variability in the Indonesian Seas. This effect is suppressed along the western pathway by strong ITF advection, resulting in a spatial pattern with greater variability toward the Banda Sea. ENSO-driven thermocline changes over Western Pacific further modulates the seasonal SST variability in this region, revealing a previously unidentified oceanic pathway linking ENSO to regional SST variability. These findings deepen our understanding of ocean-driven SST variability and its climate significance.

  4. Physical oceanographers, climate scientists.

  5. Sea Surface Temperature (SST), ITF, ENSO, ACCESS-OM2


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