Japan Geoscience Union Meeting 2025

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[E] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-OS Ocean Sciences & Ocean Environment

[A-OS13] Exploring Variability and Changes in Ocean Biogeochemical Cycles

Wed. May 28, 2025 1:45 PM - 3:15 PM 101 (International Conference Hall, Makuhari Messe)

convener:Yohei Takano(British Antarctic Survey), Jerry Tjiputra(Norwegian Research Centre, Bjerknes Centre for Climate Research), Hidetaka Kobayashi(Faculty of Science, The University of Toyama), Ryohei Yamaguchi(Japan Agency for Marine-Earth Science and Technology), Chairperson:Yohei Takano(British Antarctic Survey), Jerry Tjiputra(Norwegian Research Centre, Bjerknes Centre for Climate Research), Ryohei Yamaguchi(Japan Agency for Marine-Earth Science and Technology), Hidetaka Kobayashi(Faculty of Science, The University of Toyama)

3:00 PM - 3:15 PM

[AOS13-06] Dissolved oxygen variability in the tropical Pacific: Insights from models and observations

*Yassir Eddebbar1 (1.Scripps Institution of Oceanography, University of California San Diego)

Keywords:ENSO, Dissolved Oxygen, Climate Variability, Ocean Biogeochemistry

The dissolved oxygen (O2) content of the tropical Pacific showcases substantial variability from interannual to decadal timescales, challenging the detection of ocean deoxygenation in this region. This variability is particularly elevated in the upper equatorial Pacific, where the equatorial current system and its generated shear are highly energetic and dominate the supply of O2 in this region. Using a global observational synthesis of O2, an eddy-resolving and non-eddying 60-year hindcast simulations of the Community Earth System Model (CESM), we examine the interannual variability of O2 and its underlying drivers in the tropical Pacific. We find a tight relationship emerges between El Niño Southern Oscillation (ENSO) and the O2 content and distribution across observations and models, with elevated O2 in the eastern and central part of the basin that is tightly linked to isopycnal heave. We find generally similar patterns of O2 response to ENSO across models and observations, though the magnitude of this response is underestimated in both model simulations. We further explore the mechanisms underlying this variability, and show that in addition to contributions by the Equatorial Undercurrent (EUC), eddy-mediated vertical mixing and changes in O2 consumption also contribute substantially to the simulated O2 response to ENSO. These results will be further discussed in the context of the readiness and potential of the observing system to monitor ocean oxygen dynamics across critical scales.