Abstract

A primitive-equation numerical model is used to examine the generation and propagation of internal-inertial waves in the Subtropical Front. The mesoscale variability in surface inertial currents is induced by radiation of internal-inertial waves out of the surface layer. On the warm side of the front, surface inertial energy is carried away by normal internal-inertial waves. A deep inertial energy maximum exists at the base of the thermocline where the effective local inertial frequency approaches the planetary inertial frequency. On the cold side of the front, the surface inertial energy is carried away by anomalously low frequency internal waves. A subsurface inertial energy maximum occurs at the top of the thermocline where the density slope becomes flat. The propagation of internal-inertial waves is consistent with the WKB approximation. On the other hand, since the upper-ocean response consists of a full spectrum of internal-inertial waves, prediction of inertial energy distribution based on ray theory is invalid. Comparison between model results and current profiler observations in the Subtropical Front is quite favorable.

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