Fig. 8 shows the correlation between a pair of co-located
fiber optic and piezoelectric sensors during the passage of the
24 cm wave train. The average correlation is good, however the
quantization of the 12-bit analogue to digital converter used
in the data acquisition unit generates large error bars and the
roll-off seen at high and low pressures. Fig. 9 shows the peakto-
trough pressures recorded by all the sensors in the vertical
array that remained below the surface during the passage of the
wave trains. The data was averaged from 10 consecutive wave
peaks recorded once the wave train had become established.
The data shows a distinct reduction in pressure with increasing
depth and the gradient becomes increasingly negative with
increasing wave height. The dashed curves in Fig