Atmospheric Synoptic Variability and Pacific Ocean Biogeochemistry in the Current and Future Climate (SyVarBio)
Final Report Abstract
Projections based on Earth system models participating in the Coupled Model Intercomparison Project (CMIP) suggest that the ocean environment will dramatically change in the next 100 years should global surface warming continue at the present rate. Changes in ocean circulation may foster the future expansion of the tropical Oxygen Minimum Zones (OMZs). One of the main mechanisms controlling the oxygen levels and the upwelling productivity is the wind-driven ocean circulation. We find that in CMIP6 models the mean Kinetic Energy (KE) contained in the Atmospheric Synoptic Variability band (0–30 days) represents more than half of the total mean average KE poleward of 20°. The annual mean KE in the ASV band decreases due to climate change in the subtropical regions, corresponding to a reduction of storminess. Conversely, the annual mean ASV KE increases in the equatorial region. Using the Kiel Climate Model, we performed model experiments to assess the long-term impact of the change in ASV on ocean upper properties in a climate change context. Compared to a control global warming experiment, maintaining ASV at current values leads to a shallowing of the ML in the tropics and a deepening in the subtropics, associated with a strengthening of the wind-driven tropical (TCs) and subtropical– tropical cells (STCs) and an increase in net primary productivity. Increasing or decreasing ASV has a linear effect on the strength of these recirculation cells, which play a large role in the surface temperature and biogeochemical variability of the equatorial ocean, especially at decadal timescale. Current and future changes in ASV need to be explicitly quantified in climate projections, as they may partly explain some of the inter-model heterogeneity.
Publications
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Final Report of TPOS 2020. GOOS-268, 83 pp
Kessler, W.S., S. Cravatte & Lead Authors
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The riddle of eastern tropical Pacific Ocean oxygen levels: the role of the supply by intermediate-depth waters. Ocean Science, 17(5), 1489-1507.
Duteil, Olaf; Frenger, Ivy & Getzlaff, Julia
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Future changes in atmospheric synoptic variability slow down ocean circulation and decrease primary productivity in the tropical Pacific Ocean. npj Climate and Atmospheric Science, 6(1).
Duteil, Olaf & Park, Wonsun
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Editorial: Constraining uncertainties in hindcasts and future projections of marine deoxygenation. Frontiers in Marine Science, 10.
Shigemitsu, Masahito; Duteil, Olaf; Ito, Takamitsu; Tjiputra, Jerry & Eddebbar, Yassir
