OBSERVATIONS ON INTERNAL WAVES IN SHALLOW WATER

Observations made off the San Diego coast in 1959 are presented and discussed. Two different systems for recording temperatures were employed and thermistors were used in both of them. The transducer component of one consists of several thermistors by which temperature is measured at fixed depths. The other system includes a sea element which is automatically and continuously positioned on a selected isotherm. Ocean temperature was simultaneously recorded at three locations. Series of internal waves of relatively high frequency usually follow high or low tide and persist for approximately one hour. Single waves that are separated from other significant thermal disturbances and not related to any particular phase of tide progress in the same area. Profiles of both types of waves show that they are strongly influenced by boundary conditions. Wave displacement is upward when the thermocline is near the bottom and downward when the thermocline is higher. Internal tides are present throughout a 7‐day record of isotherm depth. The phase relation between the surface tide and internal tide is variable over time but the period and asymmetry of the two waves are similar.