Isopycnal Submesoscale Stirring Crucially Sustaining Subsurface Chlorophyll Maximum in Ocean Cyclonic Eddies

Cao, Haijin; Freilich, Mara; Song, Xiangzhou; Jing, Zhiyou; Fox‐Kemper, Baylor; Qiu, Bo; Hetland, Robert D.; Chai, Fei; Ruiz, Simón; Chen, Dake

doi:10.1029/2023gl105793

Cited by 3 publications

(1 citation statement)

References 75 publications

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“…If VHT is predominantly influenced by internal wave motions, little distinction would be seen between the eddy and front cases. The vertical transport of passive and biological tracers may be associated with submesoscale along-isopycnal stirring through both frontogenesis and small-scale instabilities (Cao et al, 2024). Further observations and insightful analyses, alongside numerical modeling, are imperative for a comprehensive understanding of the underlying dynamics.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Scale‐Dependent Vertical Heat Transport Inferred From Quasi‐Synoptic Submesoscale‐Resolving Observations

Cao,

Jing,

Fox‐Kemper

2024

Geophysical Research Letters

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Oceanic motions across meso‐, submeso‐, and turbulent scales play distinct roles in vertical heat transport (VHT) between the ocean's surface and its interior. While it is commonly understood that during summertime the enhanced stratification due to increased solar radiation typically results in an reduced upper‐ocean vertical exchange, our study reveals a significant upward VHT associated with submesoscale fronts (<30 km) through high‐resolution observations in the eddy‐active South China Sea. The observation‐based VHT reaches ∼100 W m−2 and extends to ∼150 m deep at the fronts between eddies. Combined with microstructure observations, this study demonstrates that mixing process can only partly offset the strong upward VHT by inducing a downward heat flux of 0.5–10 W m−2. Thus, the submesoscale‐associated VHT is effectively heating the subsurface layer. These findings offer a quantitative perspective on the scale‐dependent nature of VHT, with crucial implications for the climate system.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Scale‐Dependent Vertical Heat Transport Inferred From Quasi‐Synoptic Submesoscale‐Resolving Observations

Cao,

Jing,

Fox‐Kemper

2024

Geophysical Research Letters

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Interactions Between Multiple Physical Particle Injection Pumps in the Southern Ocean

Thompson,

Dove,

Flint

et al. 2024

Global Biogeochemical Cycles

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Contributions to the biological pump that arise from the physical circulation are referred to as physical particle injection pumps. A synthesized view of how these physical pumps interact with each other and other components of the biological pump does not yet exist. Here, observations from a quasi‐Lagrangian float and an ocean glider, deployed in the Southern Ocean's Subantarctic Zone for one month during the spring bloom, offer insight into daily‐to‐monthly fluctuations in the mixed layer pump (MLP) and the eddy subduction pump (ESP). Estimated independently, each mechanism contributes intermittent export fluxes of roughly several hundred milligrams of particulate organic carbon (POC) per square meter per day. The glider‐based estimates indicate sustained weekly periods of MLP export fluxes across the base of the mixed layer with a magnitude of mg POC . Potential export fluxes from the ESP, based on a mixed layer instability scaling, occasionally exceed 400 mg POC , with export elevated due to both strong inferred vertical velocities and enhanced isopycnal slopes. Significant export fluxes from the ESP are localized to the edges of mesoscale eddies and to fronts, whereas the MLP acts more broadly due to the larger scales of atmospheric forcing. Regimes occur when MLP and ESP export fluxes can have either the same or opposite sign. Simple summation of fluxes from existing parameterizations of the two pumps likely misrepresents the total physical carbon flux. Insights into how mesoscale stirring and submesoscale velocities set POC vertical structure is a key target to reduce uncertainty in global carbon export fluxes.

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Submesoscale Processes in the Northern Red Sea: Insights From Underwater Glider Observations

Chu,

Yu,

Krokos

et al. 2024

JGR Oceans

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The critical role of oceanic submesoscale currents in promoting energy cascade and modulating biogeochemical processes as well as the heat budget in the upper ocean has gained wide recognition. Although high‐resolution numerical simulations have enabled qualitative investigation of the spatiotemporal variability of submesoscale processes in the north Red Sea (NRS), observational evidence remains scarce. This study investigated the submesoscale processes in the NRS through field observations of underwater gliders. High‐resolution glider and satellite observation data sets reveal the spatiotemporal variation characteristics of submesoscale fronts and deepen mixed layer depth during winter. Diagnosis of potential vorticity (PV) and classifications of submesoscale instabilities demonstrate conducive conditions for the mixed layer baroclinic, gravitational, and symmetric instability. The significant negative PV induced by atmospheric cooling associated with robust fronts promotes the development of submesoscale processes. Combining the Omega equation with biogeochemical observations suggests that coherent pathways via submesoscale processes lead to the vertical transport of biomass and oxygen patches, supplying nutrients into the euphotic layer and ventilating hypoxic waters at depths. These results demonstrate the fundamental role of submesoscale processes in the ocean dynamics of the NRS.

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Isopycnal Submesoscale Stirring Crucially Sustaining Subsurface Chlorophyll Maximum in Ocean Cyclonic Eddies

Cited by 3 publications

References 75 publications

Scale‐Dependent Vertical Heat Transport Inferred From Quasi‐Synoptic Submesoscale‐Resolving Observations

Scale‐Dependent Vertical Heat Transport Inferred From Quasi‐Synoptic Submesoscale‐Resolving Observations

Interactions Between Multiple Physical Particle Injection Pumps in the Southern Ocean

Submesoscale Processes in the Northern Red Sea: Insights From Underwater Glider Observations

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