lightning damage, but protective measures have been taken to minimize such 

 occurrences. A more complete description of the gages' operational charac- 

 teristics was given by Grogg (1986) . 

 Buoy gage 



31. One Datawell Laboratory for Instrumentation (Haarlem, The Nether- 

 lands) Waverider buoy gage (Gage 630) measures the vertical acceleration pro- 

 duced by the passage of a wave. The acceleration signal is double- integrated 

 to produce a displacement signal which is transmitted by radio to an onshore 

 receiver. The manufacturer stated that wave amplitudes are correct to within 

 3 percent of their actual value for wave frequencies between 0.065 and 

 0.500 Hz (corresponding 15- to 2-sec wave periods). The manufacturer also 

 specified that the error gradually increased to 10 percent for wave periods in 

 excess of 20 sec. The results in this report were not corrected for the 

 manufacturer's specified amplitude errors. However, the buoy was calibrated 

 semiannually to ensure that it was within the manufacturer's specification. 

 Pressure gage 



32. One Senso-Metrics , Incorporated (Simi Valley, CA) , pressure trans- 

 duction gage (Gage 111) installed near the ocean bottom measures the pressure 

 changes produced by the passage of waves creating an output signal which is 

 linear and proportional to pressure when operated within its design limits. 

 Predeployment and postdeployment precision calibrations are performed at the 

 FRF using a static deadweight tester. The sensor's range is to 25 psi 

 (equivalent to 0- to 17-m seawater) above atmospheric pressure with a 

 manufacturer- stated accuracy of ±0.25 percent. Copper scouring pads are 

 installed at the sensor's diaphragm to reduce biological fouling, and the 

 system is periodically cleaned by divers. 



Digital Data Analysis and Summarization 



33. The data were collected, analyzed, and stored on magnetic tape 

 using the FRF's VAX computer. Data sets were normally collected every 6 hr. 

 During storms, the collection was at 3-hr intervals. For each gage a data set 

 consisted of 4 contiguous records of 4,096 points recorded at 0.5 Hz (approxi- 

 mately 34-min long) , for a total of 2 hr and 16 min. Analysis was performed 

 on individual 34-min records. 



34. The analysis program computes the first moment (mean) and the 



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