January 2014 - TD 302 Operating Manual for Pressure 4117/4117R Tide 5217/5217R, Wave & Tide 5218/5218RPage 65
difference between the true dynamic pressure and the observed dynamic pressure before the wave parameters
can be calculated.
The damping of the dynamic pressure can be described by the Linear Wave Theory (sometimes known as the Airy
Wave Theory). Figure A 4 illustrates the damping of the dynamic pressure as a function of the wave period in [m]
and of the deployment depth. A small damping factor means that the dynamic pressure is significantly damped,
while less damped when the damping factor is larger; as the damping factor approaches 1, the observed dynamic
pressure approaches the true dynamic pressure.
To compensate for the damping of the dynamic pressure, the power spectrum is multiplied with a
transfer function that is the inverse of the function describing the damping of the dynamic pressure.
Figure A 4 Damping of the dynamic pressure in deep water as a factor of wave period and
deployment depth.
Linear Wave Theory:
The Linear Wave Theory provides a number of equations that can be applied to compute wave properties as e.g.
significant wave height, mean zero crossing and mean wave period.
