No abstract

Measurements from three vertical line arrays of temperature probes, deployed in a triangular configuration in the Santa Barbara Channel in August 2002, permitted determination of speed and direction of tidally generated internal solitary wave events (ISWEs). Two arrays were deployed 2 km apart along a 60-m isobath, with the third normal to the isobath. Sound propagation measurements were also conducted along the isobath. Highly correlated ISWEs were evident on all three arrays every 12 h. Measurements of time delays suggest that these waves emanated from a single site between two of the Channel Islands. Because the ISWE propagation direction was nearly normal to the acoustic propagation direction, acoustic mode coupling due to ISWEs is expected to be minimal. Time-series temperature measurements reveal that average near-surface sound speeds were systematically different when ISWEs were present or absent, and changed abruptly during transitions. Numerical simulations with a normal mode propagation code (C−SNAP) indicate that frequency-dependent differences in transmission loss on near-bottom hydrophones may be as large as 7 dB in narrow frequency bands (5%–10%) between 0.5 and 2 kHz when an ISWE is present versus when it is absent. [Work supported by ONR.]