INTERNAL TIDE ACOUSTIC TOMOGRAPHY: RELIABILITY OF THE NORMAL MODES EXPANSION AS A POSSIBLE BASIS FOR SOLVING THE INVERSE PROBLEM

摘要

Using hydrodynamic and thermodynamic equations appropriate for modelling internal tides, one can predict the current and temperature distributions associated with the ocean's dynamic modes. Comparing, such predictions with observations from the INTIMATE'96 experiment, we find a high degree of correlation between the first 3 theoretically calculated dynamic modes and corresponding empirical orthogonal functions (EOF's) derived from an ensemble of temperature and current profiles. The implications are twofold. First, this implies that the dominant variability in the INTIMATE'96 experiment is indeed associated with internal tides. Secondly, it suggests that in future tidal experiments a theoretically generated basis may be used as effectively as an EOF basis (which requires more extensive oceanographic. measurements). We have also used the set of dynamic modes to simulate the effect of the tides on acoustic propagation to understand the relative importance of the usual surface tide (barotropic) and the internal (baroclinic) tides.