Periodic motions of the seasonal thermocline along the southern California coast

An investigation off the southern California coast has shown that a significant part of seasonal thermocline motion is caused by wind transport. A linear relationship for this motion, which takes into account the 14- to 16-hour response time occurring between wind and depth changes, has been established. Through this relationship it is possible to compute and predict movements of the thermocline caused by the wind. Those found to occur regularly include a diurnal oscillation, an oscillation of 4½-day period, and an over-all upward trend throughout the summer. Tidal thermocline oscillations were studied with the wind effects removed. It was found that during the 4 months of nearly continuous thermocline depth data the internal tide lagged the surface tide by 3 to 5 hours and averaged 4 or 5 times as great in amplitude.