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Benthic storms

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A benthic storm, also known as a deep-sea storm, is an episodic period of intense bottom current that is capable of sediment resuspension in the deep ocean, typically associated with enhanced bottom-water turbidity.[1] They form in response to the instability of surface currents. This leads to the formation of strong cyclonic and anticyclones currents throughout the water column. They are able to generate deep cyclones, anticyclones, and/or topographic waves. These create currents with sufficient bed-shear stress to erode and resuspend sediment from the sea floor that initiates or enhances benthic storms. Particulate matter eroded from the seafloor by the bottom currents also go into forming a nepheloid layer.[2][3][4]

Occurrence

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Benthic storms often occur with Gulf Stream meanders.

Benthic storms are most frequently occurring beneath Gulf Stream meanders and its associated rings. Other areas where they occur frequently include the New England Seamounts and the North Atlantic Current near the Flemish Cap.[1][3] They have also been observed in other areas with energetic surface ocean currents, including the Argentine Basin[5], the Agulhas Retroflection Zone[6], the Gulf of Mexico[7], and the Gulf of Lions in the Mediterranean[8] and areas of the Southern Ocean[9]. In the Kuroshio Extension, enhanced bottom currents were observed[10] without increased turbidity[11]. Some observation suggests they could also occur in the eastern tropical Pacific where polymetallic nodules exist[12].

Mechanism

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Benthic storms will often form nepheloid layers from the sediment they re-suspend. This one is located in the Gulf of Mexico.

They occur in areas with high sea-surface eddy kinetic energy (EKE). It also seems that they require a mixed barotropic–baroclinic instability-driven cyclogenesis to generate. A jet located near the surface developed meanders evolving into alternating and deep reaching cyclones and anticyclones. Simultaneously, the kinetic energy of high surface eddies increases near the bottom due to the convergence of vertical eddy pressure fluxes. They can then form bottom mixed layers that can have thicknesses of 100 meters, mainly from enhanced velocity shears and near-bottom turbulence production. Fluid particles are transported both laterally and vertically from the near bottom through the mixed bottom layer from deep cyclonic eddies. Varying intensities of deep current with distance from the bottom creates turbulence which leads to well-mixed layers. Deep varying transport particles from the near-bottom upward through the entire mixed layers.[2]

Benthic storms seem to show a high range of variability in velocity, intensity, etc.[13][14]

History

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In oceanography, it was a long held assumption that the water in the benthic boundary layer (BBL) located above the abyssal sea floor would be rather still. However it was revealed that the BBL was not static and instead different areas have dramatically different velocities. Benthic storms were first extensively absorbed along the continental rise of Nova Scotia and the Argentine Basin during the late 1970s and early 1980s with the High Energy Benthic Boundary Layer Experiment (commonly known as the HEBBLE program).[15]

Despite a long history of observation, their mechanisms of formation and their relationship with deep ocean salient features such as bottom mixed layers (BMLs) and benthic nepheloid layers (BNLs) have been poorly understood.[2][15]

Importance

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They are important for both the energy budget of the ocean and for sediment resuspension and transport.[3] The particulate matter is suspends also scavenge adsorption-prone radionuclides. They are used as proxies for paleo-productivity and for the investigation of circulation in modern and paleo-oceans[16]. Knowledge on how they are sourced, transported, and deposited will help to determine where scavenging is most likely to occur and to assess its impact on global biogeochemistry.[1]

References

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  1. 1 2 3 Gardner, Wilford D.; Tucholke, Brian E.; Richardson, Mary Jo; Biscaye, Pierre E. (2017-03-01). "Benthic storms, nepheloid layers, and linkage with upper ocean dynamics in the western North Atlantic". Marine Geology. 385: 304–327. Bibcode:2017MGeol.385..304G. doi:10.1016/j.margeo.2016.12.012. hdl:1912/8971. ISSN 0025-3227.
  2. 1 2 3 Chen, Si-Yuan Sean; Marchal, Olivier; Gardner, Wilford; Andres, Magdalena (July 2024). "Intensified Currents Associated With Benthic Storms Underneath an Eddying Jet". Journal of Geophysical Research: Oceans. 129 (7) e2024JC020963. Bibcode:2024JGRC..12920963C. doi:10.1029/2024JC020963. ISSN 2169-9275.
  3. 1 2 3 Schubert, René; Biastoch, Arne; Cronin, Meghan F.; Greatbatch, Richard J. (2018-10-01). "Instability-Driven Benthic Storms below the Separated Gulf Stream and the North Atlantic Current in a High-Resolution Ocean Model". Journal of Physical Oceanography. 48 (10): 2283–2303. Bibcode:2018JPO....48.2283S. doi:10.1175/JPO-D-17-0261.1. Retrieved 2026-04-13.
  4. ↑ Chen, Si-Yuan Sean; Marchal, Olivier; Andres, Magdalena; Gardner, Wilford; Yang, Jiayan; Peacock, Thomas (2026). "Deep Cyclones and Benthic Storms in the Western North Atlantic: New Insights From a Regional Circulation Model". Journal of Geophysical Research: Oceans. 131 (5) e2025JC023298. Bibcode:2026JGRC..13123298C. doi:10.1029/2025JC023298. ISSN 2169-9291.
  5. ↑ Richardson, Mary Jo; Weatherly, Georges L.; Gardner, Wilford D. (January 1993). "Benthic storms in the Argentine Basin". Deep Sea Research Part II: Topical Studies in Oceanography. 40 (4–5): 975–987. Bibcode:1993DSRII..40..975R. doi:10.1016/0967-0645(93)90044-N.
  6. ↑ Chereskin, T. K.; Donohue, K. A.; Watts, D. R.; Tracey, K. L.; Firing, Y. L.; Cutting, A. L. (December 2009). "Strong bottom currents and cyclogenesis in Drake Passage". Geophysical Research Letters. 36 (23) 2009GL040940. Bibcode:2009GeoRL..3623602C. doi:10.1029/2009GL040940. ISSN 0094-8276.
  7. ↑ Gardner, Wilford D.; Richardson, Mary Jo; Mishonov, Alexey V.; Bean, Daniel A.; Herguera, Juan Carlos (2022-12-01). "Nepheloid layers in the deep Gulf of Mexico". Marine Geology. 454 106950. Bibcode:2022MGeol.45406950G. doi:10.1016/j.margeo.2022.106950. ISSN 0025-3227.
  8. ↑ Durrieu de Madron, X.; Ramondenc, S.; Berline, L.; Houpert, L.; Bosse, A.; Martini, S.; Guidi, L.; Conan, P.; Curtil, C.; Delsaut, N.; Kunesch, S.; Ghiglione, J. F.; Marsaleix, P.; Pujo-Pay, M.; Séverin, T. (March 2017). "Deep sediment resuspension and thick nepheloid layer generation by open-ocean convection". Journal of Geophysical Research: Oceans. 122 (3): 2291–2318. Bibcode:2017JGRC..122.2291D. doi:10.1002/2016JC012062. ISSN 2169-9275.
  9. ↑ Chereskin, T. K.; Donohue, K. A.; Watts, D. R.; Tracey, K. L.; Firing, Y. L.; Cutting, A. L. (December 2009). "Strong bottom currents and cyclogenesis in Drake Passage". Geophysical Research Letters. 36 (23) 2009GL040940. Bibcode:2009GeoRL..3623602C. doi:10.1029/2009GL040940. ISSN 0094-8276.
  10. ↑ Greene, Andrew D.; Watts, D. Randolph; Sutyrin, Georgi G.; Sasaki, Hideharu (2012-09-01). "Evidence of Vertical Coupling between the Kuroshio Extension and Topographically Controlled Deep Eddies". Journal of Marine Research. 70 (5): 719–747. Bibcode:2012JMR....70..719G. doi:10.1357/002224012806290723.
  11. ↑ Gardner, Wilford D.; Richardson, Mary Jo; Mishonov, Alexey V. (2018-01-15). "Global assessment of benthic nepheloid layers and linkage with upper ocean dynamics". Earth and Planetary Science Letters. 482: 126–134. Bibcode:2018E&PSL.482..126G. doi:10.1016/j.epsl.2017.11.008. ISSN 0012-821X.
  12. ↑ Kontar, Evgeny A.; Sokov, Alexey V. (July 1994). "A benthic storm in the northeastern tropical Pacific over the fields of manganese nodules". Deep Sea Research Part I: Oceanographic Research Papers. 41 (7): 1069–1089. Bibcode:1994DSRI...41.1069K. doi:10.1016/0967-0637(94)90019-1.
  13. ↑ Kontar, Evgeny A.; Sokov, Alexey V. (1994-07-01). "A benthic storm in the northeastern tropical Pacific over the fields of manganese nodules". Deep Sea Research Part I: Oceanographic Research Papers. 41 (7): 1069–1089. Bibcode:1994DSRI...41.1069K. doi:10.1016/0967-0637(94)90019-1. ISSN 0967-0637.
  14. ↑ Gardner, Wilford D.; Sullivan, Lawrence G. (1981-07-17). "Benthic Storms: Temporal Variability in a Deep-Ocean Nepheloid Layer". Science. 213 (4505): 329–331. Bibcode:1981Sci...213..329G. doi:10.1126/science.213.4505.329. PMID 17819902.
  15. 1 2 Quirchmayr, R. On the Existence of Benthic Storms. J Nonlinear Math Phys 22, 540–544 (2015). https://doi.org/10.1080/14029251.2015.1113053
  16. ↑ Chen, Si-Yuan Sean; Marchal, Olivier; Lerner, Paul E.; McCorkle, Daniel C.; Rutgers van der Loeff, Michiel M. (2021-11-01). "On the cycling of 231Pa and 230Th in benthic nepheloid layers". Deep Sea Research Part I: Oceanographic Research Papers. 177 103627. doi:10.1016/j.dsr.2021.103627. ISSN 0967-0637.
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