The Cape Ghir filament system in August 2009 (NW Africa)

Abstract

In the framework of the Canaries-Iberian marine ecosystem Exchanges (CAIBEX) experiment, an interdisciplinary high-resolution survey was conducted in the NW African region of Cape Ghir (30838 0 N) during August 2009. The anatomy of a major filament is investigated on scales down to the submesoscale using in situ and remotely sensed data. The filament may be viewed as a system composed of three intimately connected structures: a small, shallow, and cold filament embedded within a larger, deeper, and cool filament and an intrathermocline anticyclonic eddy (ITE). The cold filament, which stretches 110 km offshore, is a shallow feature 60 m deep and 25 km wide, identified by minimal surface temperatures and rich in chlorophyll a. This structure comprises two asymmetrical submesoscale (18 km) fronts with jets flowing in opposite directions. The cold filament is embedded near the equatorward boundary of a much broader region of approximately 120 km width and 150 m depth that forms the cool filament and stretches at least 200 km offshore. This cool region, partly resulting from the influence of cold filament, is limited by two asymmetrical mesoscale (50 km) frontal boundaries. At the ITE, located north of the cold filament, we observe evidence of downwelling as indicated by a relatively high concentration of particles extending from the surface to more than 200 m depth. We hypothesize that this ITE may act as a sink of carbon and thus the filament system may serve dual roles of offshore carbon export and carbon sink.

Fronts at the Surface Ocean Can Shape Distinct Regions of Microbial Activity and Community Assemblages Down to the Bathypelagic Zone: The Azores Front as a Case Study

“…The combined effect of strong upwelling filaments, like those stretching from Cape Sao Vicente (Relvas and Barton, 2002) and Cape Guir (Sangrà et al, 2015), and mesoscale eddies ) may extend the transport hundreds of miles to the open ocean. Particularly, the Cape Guir filament is known to export a large fraction of the coastal primary production to the open ocean (García-Muñoz et al, 2004;Pelegrí et al, 2005;Santana-Falcón et al, 2016).…”

Comparative study of age estimation in wild and cultured Octopus vulgaris paralarvae: effect of temperature and diet

“…The youngest oceanic paralarvae with 2−4 increments (i.e. 2−4 d old) caught in Morocco were dispersed far from the coast by the strong upwelling filament recorded off the NW African coast during the CAIBEX-III survey (Sangrà et al 2015). This upwelling filament was 120 km wide, 150 m deep and stretched more than 200 km offshore, thus transporting recently hatched paralarvae from the coast that were growing within the filament, as evidenced from Fig.…”

“…Between these 2 Lagrangian experiments, we collected samples following a coastal−oceanic gradient off the Portuguese coast (S8−S10), to see the changes between these 2 environments, as well as 2 samples in the continental shelf of Galicia (S11 and S12). In contrast, strong winds during CAIBEX-III allowed the development of a strong upwelling filament (Sangrà et al 2015). The IDB was deployed in the core of the upwelling filament, which was advected from the coast into the ocean during the third Lagrangian experiment (L3: 23−31 August, Fig.…”

“…a) Iberian−Canary current eastern boundary upwelling system modified fromArístegui et al (2009), showing the areas sampled (red box: CAIBEX-I cruise, pink box: CAIBEX-III) and the main currents (light blue: surface; dark blue: slope; SC: slope current), retention (orange) and dispersion (green) zones on the shelf. (b) Ría of Vigo (NW Spain) showing the 2 transects (T1 and T2) where 'coastal' Octopus vulgaris paralarvae were sampled.…”

Twenty-Seven Years of Scatterometer Surface Wind Analysis over Eastern Boundary Upwelling Systems

“…The positive wind vorticity pattern along the African coast is captured by all analyses with a somewhat weaker magnitude in the CCMP. Wind stress curl along the African coast is not homogeneous and is spatially modulated by orographic interactions over major capes along the Morocco-Mauritania coast (e.g., Cape Ghir, Sim, Juby [34]). All the above coastal features amplify in summer when the northeasterly trade winds strengthen.…”