2024-03-29T01:24:55Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1694822020-05-25T12:46:11Zcom_10261_47com_10261_8col_10261_300
Modulation of the Semidiurnal Cycle of Turbulent Dissipation by Wind-Driven Upwelling in a Coastal Embayment
Fernández-Castro, B.
Gilcoto, Miguel
Naveira-Garabato, Alberto
Villamaña, Marina
Graña, R.
Mouriño-Carballido, Beatriz
21 pages, 12 figures
With two 25‐hour series of turbulent microstructure and currents observations carried out in August 2013, during spring (CHAOS 1) and neap tides (CHAOS 2), we investigated the semidiurnal cycle of turbulent dissipation in an embayment affected by coastal upwelling (Ría de Vigo, NW Iberia). At the time of sampling, the bay hosted a net, wind‐driven bi‐directional positive exchange flow and thermal stratification. Turbulent kinetic energy (TKE) dissipation (ɛ) at the interface between upwelled and surface waters was enhanced by two orders of magnitude during the ebbs ( urn:x-wiley:21699275:media:jgrc22950:jgrc22950-math-0001 W kg− 1) with respect to the floods ( urn:x-wiley:21699275:media:jgrc22950:jgrc22950-math-0002 W kg− 1). This pattern was caused by the constructive interference of the shear associated with the upwelling and tidal currents. The vertical structure of the tidal currents was consistent with a deformation of tidal ellipses by stratification, which was tightly coupled to the intensity of upwelling. This two‐pronged interaction resulted in a modulation of the semidiurnal cycle of turbulent dissipation by coastal upwelling. Thus, as a result of the upwelling relaxation conditions experienced during CHAOS 1, depth‐integrated interior TKE dissipation rates were higher, by a factor of urn:x-wiley:21699275:media:jgrc22950:jgrc22950-math-0003, compared to CHAOS 2. By using a simple model, we determined that observed variations in turbulent mixing had a limited influence on the tidal variations of stratification, which were dominated by straining and advection. The mixing mechanism described here is potentially relevant for the ecology of upwelling bays, as it can stimulate the transport of nutrients from deep‐upwelled waters to the sun‐lit surface layers where primary production takes place
2018-09-07T11:59:55Z
2018-09-07T11:59:55Z
2018
artículo
Journal of Geophysical Research - Part C - Oceans 123(6): 4034-4054 (2018)
http://hdl.handle.net/10261/169482
10.1002/2017JC013582
2169-9291
eng
Publisher's version
https://doi.org/10.1002/2017JC013582
Sí
openAccess
American Geophysical Union