January 2014 - TD 302 Operating Manual for Pressure 4117/4117R Tide 5217/5217R, Wave & Tide 5218/5218RPage 67
Cut-off Frequency
:
The WTS is applicable for studies of waves with wave period as small as 1 second without aliasing, according to the
Nyquist theorem. However, the dynamic pressure caused by waves with short wave period is damped rapidly with
depth, see Figure A , hence the WTS calculates a cut-off frequency based on the deployment depth as measured by
the pressure sensor
:
d
g
f
Off
Cut
⋅
=
−
282
.
0
where
g
is the gravitational coefficient and
d
the deployment depth.
Calculation of Wave parameters
The sea conditions can be described by a number of wave parameters, like e.g.
Significant Wave Height
Maximum Wave Height
Mean Zero Crossing
Peak Wave Period
Mean Wave period
Energy Wave Period
Irregularity
Wave Steepness
These parameters are provided by the WTS, and will be described below. For more information regarding the wave
parameters, see the ‘
Guide to Wave Analysis and Forecasting
’, World Meteorological Organization (WMO) report
number 702.
6
IEEE Journal of Oceanic Engineering, VOL 26, No2, April 2001, p 171-180