| Summary: | The role of strong atmospheric forcing events in determining the evolution of the upper ocean during the fall and early winter cooling season was investigated. The historical series of surface and near-surface marine observations at three mid-latitude ocean weather ships (PAPA (OWS P), NOVEMBER (OWS N), and VICTOR (OWS V)) support the hypothesis that the integrated effects of these events dominate this evolution. For example, periods when the mechanical forcing was greater than the long-term mean accounted for approximately 35% of the time in the record examined at the three stations. However 85%/68%/57% of the sea-surface temperature change at OWS N/OWS P/OWS V occurred during these periods. Forty-nine data sets were examined and modeled during periods of intense fall and winter forcing. The significant thermal structure modifications observed during these strong events were simulated successfully using three modifications of the Kraus and Turner (1967) one- dimensional model. Evidence is presented which demonstrates that the amount of mechanically-generated turbulent kinetic energy available for entrainment decreases as the mixed-layer depth increases. Furthermore, in agreement with Gill and Turner (1976), these case studies suggest that only a small percentage of the convectively-generated turbulent kinetic energy is available for increasing the potential energy of the ocean by entrainment. (Author)
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