| Autor: |
Villacieros‐Robineau, Nicolás1 nvrobineau@gmail.com, Zúñiga, Diana1, Barreiro‐González, Beatriz1, Alonso‐Pérez, Fernando1, Granda, Francisco2, Froján, María1, Collins, Curtis A.3, Barton, Eric Desmond1, Castro, Carmen González1 |
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| Zdroj: |
Journal of Geophysical Research. Oceans. Dec2019, Vol. 124 Issue 12, p9531-9552. 22p. |
| Abstrakt: |
The dynamics of the bottom boundary layer and their effects on the development of nepheloid layers (NLs) on a high‐energy and upwelling‐affected margin, the NW Iberian continental shelf, were studied by means of ADP currents, wave time series, and across‐shelf hydrographic surveys covering an entire annual cycle. The bottom boundary layer hydrodynamics showed that high levels of bottom shear stress over the inner shelf occurred mainly during downwelling seasons, when there was a coupling between storm waves and intense currents. This wave‐current coupling promotes strong resuspension events that favored the generation of bottom NLs (BNLs). BNLs were well developed on the inner continental shelf inshore of a thermohaline front generated by the interaction of the Iberian Poleward Current and the West Iberian Buoyant Plume. The existence of this front limited the extent of offshore export of resuspended particles during the downwelling season. In contrast, during the upwelling season, only thin BNLs were developed, and surface NLs, principally composed by biogenic particulate material, were advected offshore in the Ekman layer, often as part of the development of upwelling filaments. Our study confirmed that wave orbital velocity under stormy conditions, in combination with the hydrography, could explain the shoreward boundary of the Galician mud depocenter. Plain Language Summary: This manuscript mainly focuses on hydrodynamics of the bottom boundary layer and the effect of wave‐current bottom shear stress on the development and modulation of nepheloid layers on the NW Iberia continental shelf during more than 1 year. During this period, we analyze the role of hydrographic seasonality of this coastal upwelling system in the behavior of nepheloid layers and the possible offshore export pathways of particulate matter to the adjacent ocean. In addition, wave climate over the continental shelf was analyzed together with this hydrographic context in order to explain the surface sediment distribution. Key Points: During downwelling season, wave‐current shear stress promotes bottom nepheloid layers limited to the inner shelf by a thermohaline frontDuring the upwelling season, biogenic surface nepheloid layers transport material offshore in the Ekman layerStorm wave conditions combined with hydrography are key factors that explain the sediment distribution on the Galician continental shelf [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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