Variability of internal tides in the Laurentian Channel

摘要: Data from three sequential stations of thermistor chains and current meters along the main axis lower St. Lawrence estuary during summer-fall period in 1978 were analyzed to help understand generation variability internal tide. The Lagrangian (or direct tracing) method has been developed compute displacements tides, which can overcome limitations Eulerian caused by very small vertical temperature gradients. Internal tides semidiurnal frequency observed, but diurnal not, both time domain band. surface tide behaves like a standing wave rather than progressive one. Due nonlinear interaction tide, generated locally near sill, with topography, quarter-diurnal higher oscillations also generated. displacement reach 80, 40 30 m spring respectively, at station 1, two downstream 3 5. propagate seaward attenuation downstream, mainly results changing stratification conditions, may be partly attributed breaking turbulent mixing upper layer bottom lateral friction. amplitude ratio S2/ M2 is smaller (0.2) for baroclinic barotropic (0.24) 1 becomes larger This implies presence narrower response band forcing site. Poincare type, three-dimensional structure. “nutrient pumping” due was confirmed occur only region convergence zone primary productivity considered equivalent “rotor clouds” atmospheric mountain waves.