Extensive independent measurements of the temperature, salinity, and velocity fields were also made. The deep-turning rays are stable and yield differential travel times that give reasonable values for the current components along the acoustic paths. Finally, the acoustic signals show the effects of the nonlinear internal waves present in the Strait. A 'dot plot' showing travel times of several rays during transmissions from instrument T1 to T2. Deep-going rays arrive first, vary with current, and are shown in green.
Shallow rays are more complicated, and can even reorder themselves.
Instrument motion data reveals when internal bores pass the source, and those times are noted in red. A closeup look at the same data in Fig.1 over only one day. Note the discontinuity in travel time with each passing of the bore. Decreasing travel times until the bore passes are associated with a temperature increase as warm shallow water is displaced deeper by the bore. Summed travel times show low frequency temperature variation.