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https://doi.org/10.5194/egusphere-2024-2386
https://doi.org/10.5194/egusphere-2024-2386
02 Aug 2024
 | 02 Aug 2024

The influence of a submarine canyon on the wind-driven downwelling circulation over the continental shelf

Pedro Figueroa, Gonzalo Saldías, and Susan Allen

Abstract. The response of a coastal ocean model, simulating a typical Eastern Boundary system, to downwelling-favorable winds with and without the presence of a submarine canyon is studied. Three contrasting bathymetric configurations, considering shelves with different depth and slopes, are evaluated. Experiments without a submarine canyon represent the well-known downwelling circulation and cross-shore structure with a downwelling front and the development of frontal instabilities generating density anomalies in the bottom layer. The presence of the submarine canyon drives important changes in cross-shore flows, with opposing velocities on either side of the canyon. Onshore (offshore) and downward (upward) velocities develop in the upstream side of the canyon in the time-dependent and advective phases. Instabilities developed and are modified principally downstream of the canyon. Overall, the net impact of the canyon is to enhance offshore and downward transport. However, particle tracking experiments reveal that particles can become trapped inside the canyon in an anticyclonic circulation when the particles pass the canyon over the continental slope or when particles inside the canyon are affected by downwelling conditions. Overall, ~20–23 % (~15–18 %) of particles released directly upstream (in the canyon) at mid-depths become trapped inside the canyon until the end of the simulations (15 days).

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Pedro Figueroa, Gonzalo Saldías, and Susan Allen

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2386', Anonymous Referee #1, 13 Sep 2024
  • RC2: 'Comment on egusphere-2024-2386', Anonymous Referee #2, 20 Sep 2024
  • RC3: 'Comment on egusphere-2024-2386', Jochen Kämpf, 26 Sep 2024
Pedro Figueroa, Gonzalo Saldías, and Susan Allen
Pedro Figueroa, Gonzalo Saldías, and Susan Allen

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Short summary
Submarine canyons are topographic features found along the continental slope worldwide. Here we use numerical simulations to study how a submarine canyon influences the circulation near the coast when winds moving poleward influence the region. Our results show that submarine canyons modify the circulation near the coast, causing strong velocities perpendicular to the coast. These changes can trap particles inside the canyon, an important mechanism to explain its role as a biological hotspot.