An additional data quality analysis was performed on each current meter 
record to determine the effect of biofouling on signal attenuation. This 
procedure, referred to as the PUV-test, Z(c), used a ratio of surface wave H,,, 
computed from pressure gauges and current meters, to estimate a gain 
correction for the current meters. The method to calculate the PUV-test 
follows. 
Pressure gauge data (in units of meters of sea water) were surface normal- 
ized by the pressure response function K(z,d,k) = coshk(z + d)/coshkd, 
where Z is gauge depth from (ensemble) mean sea level, d is total water 
depth, and & is radian wavenumber (related to radian frequency © by the 
dispersion relation 0” = gk tanhkd) immediately after Fourier transformation, 
by dividing the complex Fourier coefficients at frequencies 0 by K(z,d,k). 
Current meter data were surface normalized in a similar fashion except that the 
Fourier coefficients were divided by gk K(z,d,k). In linearized wave 
(0) 
theory, the auto-spectrum from surface normalized pressure C5) is equal to 
the sum of the auto-spectra from the two surface normalized velocity compo- 
nents C,,(0) and C,(o) for uw and v, respectively. A routine check on data 
quality for co-located pressure and current meter data , the PUV -test, is to 
compute the function ,Z’(o) = CA o)/[C_,(0) +C,(o)],which was expected 
to be unity in the wind-wave pass band of frequencies in regions where linear 
theory applies. 
The PUV-test analysis used the same gauge pairs as the exposed current 
meter analysis, current meters without colocated pressure gauges were matched 
with primary array pressure gauges at the same cross-shore coordinate. Again, 
longshore homogeneity was assumed. An average PUV-test is calculated for 
each current meter record over a select frequency range of the Z(c). This 
PUV-test is averaged over the half-power bandwidth in the pressure gauge 
energy spectra, for the spectral peak that lies in the wind-wave band (0.4 to 
0.05 Hz). These PUV-test values are used as a multiplier to adjust the mean 
current amplitudes. Inherent in this treatment is the assumption of uniform 
fouling between both axes of each current meter. Corrected and uncorrected 
current velocities, and PUV-test values are recorded in the DELILAH statistics 
database. Plots of the PUV-test values are presented in Figures ES and E6. 
These data are noisy because averages are taken over short time segments. 
PUV-test plots for current meters that are not colocated to pressure gauges are 
especially noisy. The noisiness increases with the distance between current 
meter and pressure gauge. Plots CM71, CM72, CM73 and CM74 demonstrate 
this spatial inhomogeneity. The consistent PUV-test value of less than one for 
gauge CM90 indicates the pressure gauge was either lower in the water than 
believed or the current meter was higher. 
Appendix E Stationary Instrument Data 
E11 
