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- Author or Editor: Brad De Young x
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Abstract
Current meter and CTD data are presented, describing a dense bottom current which transports Labrador Current Water into Fortune Bay, Newfoundland. The effects of rotation and friction are discussed and the three-dimensional nature of the inflow is highlighted. Geostrophy alone is unable to account for the cross-channel momentum balance. The inflow may represent an important sink for the inshore branch of the Labrador Current.
Abstract
Current meter and CTD data are presented, describing a dense bottom current which transports Labrador Current Water into Fortune Bay, Newfoundland. The effects of rotation and friction are discussed and the three-dimensional nature of the inflow is highlighted. Geostrophy alone is unable to account for the cross-channel momentum balance. The inflow may represent an important sink for the inshore branch of the Labrador Current.
Abstract
Current meter data for six mouths from the Grand Bank are analyzed to study inertial currents generated by moving storms. It is found that during periods of strong winds, but no well-defined storm system, the inertial motion exhibits no simple relationship to the local wind. During intense storms inertial currents up to 0.5 m s−1 were observed both in and below the mixed layer. Upper and lower layer currents are roughly equal in amplitude, but are 180° out of phase. To explain this observation, a two-layer, one-dimensional model is developed that successfully simulates the observed inertial currents. We show that under the conditions encountered during the storms only baroclinic inertial motion can be generated. The pressure gradient effect is not important, and the current below the mixed layer is produced by mass continuity. Wavelength computed from the continuity equation is consistent with that predicted by first-order linear theory. For inertial motion generated during periods of strong wind but no cyclone, pressure gradients and barotropic response can be important and should not be neglected.
Abstract
Current meter data for six mouths from the Grand Bank are analyzed to study inertial currents generated by moving storms. It is found that during periods of strong winds, but no well-defined storm system, the inertial motion exhibits no simple relationship to the local wind. During intense storms inertial currents up to 0.5 m s−1 were observed both in and below the mixed layer. Upper and lower layer currents are roughly equal in amplitude, but are 180° out of phase. To explain this observation, a two-layer, one-dimensional model is developed that successfully simulates the observed inertial currents. We show that under the conditions encountered during the storms only baroclinic inertial motion can be generated. The pressure gradient effect is not important, and the current below the mixed layer is produced by mass continuity. Wavelength computed from the continuity equation is consistent with that predicted by first-order linear theory. For inertial motion generated during periods of strong wind but no cyclone, pressure gradients and barotropic response can be important and should not be neglected.
Abstract
In this paper the response of Conception Bay to wind forcing is discussed. Current meter and thermistor chain observations are analysed and compared with output from a reduced-gravity numerical model. The model incorporates realistic coastal geometry and is driven by wind stress calculated from observed winds.
Moorings were deployed in the bay during 1989 and 1990. In 1990 the moorings were placed within the coastal waveguide around the head of the bay and show that southwesterly winds generate an upwelling event on the western side that moves around the head of the bay and is suggestive of Kelvin wave propagation. Data analysis shows that the thermocline response is strongly coherent between each mooring at periods of 2–10 days, and winds measured at a nearby station are found to be strongly coherent with the observed temperature fluctuations.
Two versions of the reduced-gravity model are applied—one models Conception Bay alone and ignores “upstream” influences and another includes neighboring Trinity Bay, located to the northwest and “upstream” in the sense of Kelvin wave propagation. The local model does reasonably well at reproducing the observed movement of the thermocline but underestimates its amplitude. The nonlocal model, which includes the neighboring bay, does much better at simulating the observation including the amplitude of the response, and also the upper-layer currents. The comparisons clearly show the importance of nonlocal effects.
Abstract
In this paper the response of Conception Bay to wind forcing is discussed. Current meter and thermistor chain observations are analysed and compared with output from a reduced-gravity numerical model. The model incorporates realistic coastal geometry and is driven by wind stress calculated from observed winds.
Moorings were deployed in the bay during 1989 and 1990. In 1990 the moorings were placed within the coastal waveguide around the head of the bay and show that southwesterly winds generate an upwelling event on the western side that moves around the head of the bay and is suggestive of Kelvin wave propagation. Data analysis shows that the thermocline response is strongly coherent between each mooring at periods of 2–10 days, and winds measured at a nearby station are found to be strongly coherent with the observed temperature fluctuations.
Two versions of the reduced-gravity model are applied—one models Conception Bay alone and ignores “upstream” influences and another includes neighboring Trinity Bay, located to the northwest and “upstream” in the sense of Kelvin wave propagation. The local model does reasonably well at reproducing the observed movement of the thermocline but underestimates its amplitude. The nonlocal model, which includes the neighboring bay, does much better at simulating the observation including the amplitude of the response, and also the upper-layer currents. The comparisons clearly show the importance of nonlocal effects.
Abstract
A diagnostic circulation model is developed for application to coastal regions. The three-dimensional velocity field can be calculated from a specified density field and wind-stress distribution provided transport is given on boundaries where f/H contours enter the model domain (here f is the Coriolis parameter and H is the ocean depth). The model is an extension of that of Mellor. It includes the effect of vertical mixing and bottom friction and avoids explicit calculation of the JEBAR (joint effect of baroclinicity and relief) term, which can be noisy when a realistic density field is combined with realistic topography. The model can also be used in regions of closed f/H contours. An application of the model to Conception Bay, Newfoundland, illustrates the case of calculation and yields comparisons with the more classical technique of dynamic height analysis.
Abstract
A diagnostic circulation model is developed for application to coastal regions. The three-dimensional velocity field can be calculated from a specified density field and wind-stress distribution provided transport is given on boundaries where f/H contours enter the model domain (here f is the Coriolis parameter and H is the ocean depth). The model is an extension of that of Mellor. It includes the effect of vertical mixing and bottom friction and avoids explicit calculation of the JEBAR (joint effect of baroclinicity and relief) term, which can be noisy when a realistic density field is combined with realistic topography. The model can also be used in regions of closed f/H contours. An application of the model to Conception Bay, Newfoundland, illustrates the case of calculation and yields comparisons with the more classical technique of dynamic height analysis.
