Deterministic (Cycle by Cycle) Wave Parameters

The standard measurement of waves derives from the time history of wave surface profile measured at a suitably high sampling rate; for wave buoys the measurement of the buoy motion is related to the wave surface profile through the buoy transfer function. The primary measurement requirement is the buoy heave, with measurement of other motion parameters such as surge and sway, roll pitch and yaw, and local magnetic field, allowing a more extensive interpretation of the motion of the buoy.

By combining all the motion data the AIM sensor calculates the buoy heave time history in earth coordinates, either at the measurement point, or at some other suitable reference point, typically the COG. From this time history a number of standard wave parameters are calculated using both deterministic analysis (cycle by cycle), and spectral analysis.

Note that the use of a deterministic analysis is important in establishing accurate wave parameters; with spectral analysis alone some parameters can only be estimated. For example, significant wave height (1/3 highest waves) is typically approximated using the formula 4*heave RMS, or 4*area under the heave total energy spectrum. However, the factor 4 is only valid under certain conditions, typically with waves containing a dominant single frequency and direction. In contrast, the deterministic analysis calculated the value explicitly and as defined by a number of oceanographic authorities. This also applies to other deterministic parameters such as significant wave period, 1/10 highest wave parameters, etc..

Height Parameters

Period Parameters

Significant Wave Height H1/3

Significant Wave Period T1/3

Significant Wave Height H1/10

Significant Wave Period T1/10

Maximum Wave Height HMAX

Period of Maximum Wave TMAX

RMS Wave Height HRMS

Average Wave Period TZ

Maximum Wave Period TMAX

Maximum Crest Height HCMAX

Crest Period TC

Minimum Trough Height HTMIN

Deterministic Spectral Bandwidth