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Chapter 6 



Array of Subsurface Pressure 

 Measurements 



Arrays of subsurface pressure gauges are installed in the sea in order to capture 

 directional wave field data. These instruments have an advantage over arrays of 

 water surface wave rods, as they are mounted below the surface, where they are less 

 susceptible to damage, by either the strong wave forces experienced during storms, 

 as well as vandalism or accidents with vessels. 



Unfortunately, the reason they are less susceptible to damage from wave forces is 

 because they are placed under the surface, often at the sea bed, where the action of 

 waves is the smallest. This leads to the mathematically ill-posed problem discussed 

 in chapter 3. This difficulty is somewhat mitigated by the added information made 

 available by the multiple gauges in the array, but still limits the ability to determine 

 the detail of the kinematics, particularly when there is a lot of high frequency energy 

 in the sea state. 



6.1 Formulation of Solution 



The lessons learned in the previous chapters provide for a fairly straightforward 

 determination of the formulation for adapting the LFI method to the analysis of 

 arrays of pressure gauges. The formulation for a single subsurface pressure gauge was 



