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Características de la capa límite del fondo en el Alto Golfo de California a partir de perfiles de velocidad

Keywords: gulf of california, bottom boundary layer, tidal currents.

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Abstract:

the vertical structure of currents in the upper gulf of california was studied using velocity profiles observed at a site in 25 m water depth during one fortnightly cycle, in order to determine the development of a logarithmic bottom layer and to estimate parameters derived from the law of the wall. the velocity data included two neap-tide periods in which gravity currents have been shown to develop. the currents were dominated by tidal forcing, and were oriented along-gulf, with the main axis towards 323.8°. spring tide velocity amplitude was 0.5-0.9 m s-1, decreasing to less than 0.30 m s-1 during neap tides. a logarithmic layer structure was observed within the lower half of the water column during spring tides. this layer was less than 5 m thick during neap tides, and was not observed under low velocity conditions, around the times of current reversals. the seabed shear stress values were typical of macrotidal environments, reaching ±2.5 pa under spring tide conditions and decreasing by a factor of 2-3 during neap tides. mean values of the bottom drag coefficient and seabed roughness parameter were 10-2 and 0.05 m, respectively. these relatively high values were attributed to the influence of near-bed stratification. during the two neap-tide periods, two gravity current events were observed within 4-5 m from the seabed, reaching 0.30 m s-1, intensified by the ebb tidal flow. the near-bed velocity profiles were markedly modified during these events that persisted for about three days.

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