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Revisiting the seasonal cycle of the Timor Throughflow: impacts of winds, waves and eddies

Citation

Pena-Molino, B and Sloyan, BM and Nikurashin, M and Richet, O and Wijffels, SE, Revisiting the seasonal cycle of the Timor Throughflow: impacts of winds, waves and eddies, JGR Oceans, 127, (4) Article e2021JC018133. ISSN 2169-9275 (2022) [Refereed Article]


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Copyright 2022 The Authors Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) https://creativecommons.org/licenses/by-nc-nd/4.0/

DOI: doi:10.1029/2021JC018133

Abstract

The tropical Pacific and Indian Oceans are connected via a complex system of currents known as the Indonesian Throughflow (ITF). More than 30% of the variability in the ITF is linked to the seasonal cycle, influenced by the Monsoon winds. Despite previous efforts, a detailed knowledge of the ITF response to the components of the seasonal forcing is still lacking. Here, we describe the seasonal cycle of the ITF based on new observations of velocity and properties in Timor Passage, satellite altimetry and a high-resolution regional model. These new observations reveal a complex mean and seasonally varying flow field. The amplitude of the seasonal cycle in volume transport is approximately 6 Sv. The timing of the seasonal cycle, with semi-annual maxima (minima) in May and December (February and September), is controlled by the flow below 600 m associated with semi-annual Kelvin waves. The transport of thermocline waters (<300 m) is less variable than the deep flow but larger in magnitude. This top layer is modulated remotely by cycles of divergence in the Banda Sea, and locally through Ekman transport, coastal upwelling, and non-linearities of the flow. The latter manifests through the formation of eddies that reduce the throughflow during the Southeast Monsoon, when is expected to be maximum. While the reduction in transport associated with the eddies is small, its impact on heat transport is large. These non-linear dynamics develop over small scales (<10 km), and without high enough resolution, both observations and models will fail to capture them adequately.

Item Details

Item Type:Refereed Article
Keywords:Indonesian throughflow, Indonesian seas, seasonal cycle, Kelvin waves
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate change models
UTAS Author:Nikurashin, M (Dr Maxim Nikurashin)
ID Code:149883
Year Published:2022
Funding Support:Australian Research Council (DP210100643)
Deposited By:Oceans and Cryosphere
Deposited On:2022-04-22
Last Modified:2022-05-06
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