Internal Tides Responsible for Lithogenic Inputs Along the Iberian Continental Slope. Issue 10 (7th October 2022)

• Record Type: Journal Article
• Authors: Barbot, Simon; Lagarde, Marion; Lyard, Florent; Marsaleix, Patrick; Lherminier, Pascale; Jeandel, Catherine
• Is Part Of: Journal of geophysical research. Volume 127:Issue 10(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-10-07
• Subjects: Internal tides -- sediment resuspension -- lithogenic particle transport -- geochemical tracer -- modeling -- GEOTRACES; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2022JC018816
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: This study proposes new insights for the interpretation of GEOVIDE particle measurements. Potential resuspension sites due to internal tides (ITs) have been identified along the western Iberian shelf slope using a tidal regional model. Iberian shelf is mainly a source of lithogenic material whereas Galicia Bank is a source of biogenic matter. The potential pathways for particles from the resuspension sites toward the GEOVIDE stations are identified using IBIRYS reanalysis to infer their transport by the ocean circulation. It appears that each station is influenced by a specific pathway and mixed particles from several resuspension sites. This methodology reveals that the criticality of the bathymetry slope, commonly used to track resuspension sites from internal waves, is not sufficient to investigate ITs. An explicit resolution of ITs using a numerical tidal model is required for an exhaustive identification of the resuspension sites. Plain Language Summary: Internal tides (ITs) are waves with a tidal period generated when tides cross a steep slope of the sea floor. ITs then propagate in every stratified layer of the open ocean over hundreds to thousands of kilometers. The encounter of ITs with underwater relief, either at the generation site or after propagation, results in high bottom friction that enhances sediment resuspension. Evidence of lithogenic particles was found at various depths during the GEOVIDE cruise, from the Iberian continental slope to thousands of kilometers away. The present study identifies the sites where ITs are responsible for sediment resuspension. Additionally, the oceanic circulation is investigated to establish the trajectories of the resuspended sediment that could explain the GEOVIDE measurements. Key Points: Sites of high bottom tidal velocity along the Iberian continental slope were identified using a semi‐realistic internal tides model Sediment resuspension was confirmed on five sites based on earlier sediment surveys and Shields criterion threshold Particle trajectories were proposed based on circulation modeling to improve the interpretation of geochemical tracers measurements