Marine Parameters

Below is an overview of all marine parameters:

• General Terms

• Interaction With Ocean Currents

• Bathymetry

• Ocean Current

• Salinity

• Sea Ice

• Stokes Drift

• Water Temperature

• Wave Direction

• Wave Height

• Wave Period

Each parameter is explained in more detail on the respective pages.

General Terms

The two-dimensional wave spectrum describes the distribution of the wave energy as a function of frequency and propagation direction. In numerical implementation, the spectrum is discretized using 36 frequencies and 36 directions. The frequency spectrum is obtained by integrating over all directions.
The wave components in the spectrum are divided into wind sea (wind waves) and swell.

• full wave spectrum: wind waves + total swell
• wind sea: wind sea is defined as those wave components that are still growing or being sustained by the wind. In contrast to swell, these waves propagate mainly in the direction of the wind.
• swell: the remaining part of the spectrum is termed swell. Swell consists of a series of mechanical waves that propagate along the interface between water and air (surface gravity waves)
• total swell: if the full remaining part of the spectrum is considered as one entity (full spectrum excluding wind waves).
• first/second/third swell: when the remaining part of the spectrum is split into the 3 most energetic systems (descending in the respective wave heights).
• moments for periods:
  • first: reciprocal of mean frequency
  • second: reciprocal of the variance of the frequency spectrum
• significant height: the average height of the highest third of the waves
• peak period: defined for the full wave spectrum, reciprocal of the peak frequency (period of the most energetic frequency)
• wave direction: according to meteorological convention - 0° means from northern direction
• stokes drift: stokes drift caused by full wave spectrum

Interaction With Ocean Currents

Ocean current models do not consider the stokes drift in the calculation of current speeds and directions. The stokes drift can overshoot the surface ocean current in stormy conditions, but rapidly decreases with depth. In order to get a complete picture of the surface drift however, the ocean current and the stokes drift can be overlaid.