Basic HTML Version
ACT Protocols for Wave Measurement Systems
July 2012
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with other ongoing efforts (e.g. CDIP evaluation protocols) that will provide additional data for
comparisons and will facilitate the involvement of databases obtained from other ongoing
efforts.
The matrix (Figure 1) displays the range of conditions where it may be possible to evaluate
instrument performance. The dashed line indicates the JONSWAP spectrum (Hasselmann
et al
.,
1973) for an extreme wave with H
s
of 20-m. The highest frequency included here (0.5 Hz) is the
upper limit for the reference instrument (Datawell MKII) in typical deep water conditions. While
this includes most of the energy in the surface wave field, significant remote sensing applications
focus on waves with frequencies higher than this cut-off. These waves will not be included
herein. For a particular experiment to have achieved a robust comparison of sensors there should
be a sufficient number of samples at each frequency-energy bin to determine whether there is a
significant difference between mean derived parameters. This will require long duration
deployments to establish sufficient sampling over most of the intended range.
Figure 1. Sample frequency energy comparison plot of directional differences for GPS based
and MKII wave observations at Waimea, HI. Dashed line represents the extreme JONSWAP
spectrum for a wave with a 20 m H
s
.