Marine Parameters

Below is an overview of all marine parameters:

General Terms

Interaction With Ocean Currents

Significant Wave Height | Peak Wave Period | Mean Direction Total Swell | Mean Wave Direction | Max Individual Wave Height |

Mean Direction Wind Waves | Mean Period Total Swell | Mean Period Wind Waves |

Mean Wave Direction First Swell | Mean Wave Direction Second Swell | Mean Wave Direction Third Swell | Mean Wave Period | Mean Wave Period First Moment |

Mean Wave Period First Swell | Mean Wave Period Second Moment | Mean Wave Period Second Swell | Mean Wave Period Third Swell |

Significant Height Total Swell | Significant Height Wind Waves | Significant Wave Height First Swell | Significant Wave Height Second Swell | Significant Wave Height Third Swell |

Stokes Drift

Ocean Current | Water Temperature | Salinity

Bathymetry

Each parameter is explained in more detail below.

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.

Significant Wave Height

The significant wave height is traditionally defined as the mean wave height (trough to crest) of the highest third of the waves. Nowadays, it is usually defined as four times the standard deviation of the surface elevation or equivalently as four times the square root of the zeroth-order moment (area) of the full wave spectrum. ¹

significant_wave_height:m

Examples

• MetX chart showing the significant wave height along with the mean sea level pressure.

  

  Current situation:
  https://api.meteomatics.com/__replace__0Z/significant_wave_height:m/world:0.5,0.5/html_map?model=ecmwf-wam
• Show a time series of the significant wave height. The queried location lies to the south of Nagasaki in the Philippine Sea.
  https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/significant_wave_height:m/27.852903,130.116770/html

  

   

Peak Wave Period

The peak wave period is defined as the wave period associated with the most energetic waves in the total wave spectrum at a specific point. Wave regimes that are dominated by wind waves tend to have smaller peak wave periods, and regimes that are dominated by swell tend to have larger peak wave periods. ²

peak_wave_period:s

Examples

• MetX chart of the peak wave period and the mean sea level pressure.

  

  Current:
  https://api.meteomatics.com/__replace__0Z/peak_wave_period:s/world:0.5,0.5/html_map?model=ecmwf-wam
• Show a time series of the peak wave period. The queried location lies to the south of Nagasaki in the Philippine Sea.https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/peak_wave_period:s/27.852903,130.116770/html

  

   

• https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/peak_wave_period:s/27.852903,130.116770/csv

  validdate;peak_wave_period:s
  2017-08-02T00:00:00Z;12.9
  2017-08-02T01:00:00Z;12.9
  2017-08-02T02:00:00Z;12.9
  2017-08-02T03:00:00Z;13
  2017-08-02T04:00:00Z;13
  2017-08-02T05:00:00Z;13
  2017-08-02T06:00:00Z;13
  2017-08-02T07:00:00Z;13
  2017-08-02T08:00:00Z;13

Mean Direction Total Swell

Spectral mean direction in degrees over all frequencies and directions of the total swell spectrum.
The total swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind.
Please note that we are using the meteorological convention to define directions (Read more here).

mean_direction_total_swell:d

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_direction_total_swell:d/90,-180_-90,180:1000x600/html

  

Mean Wave Direction

Spectral mean direction in degrees over all frequencies and directions of the two-dimensional wave spectrum.
Please note that we are using the meteorological convention to define directions (Read more here).

mean_wave_direction:d

Examples

• Create a time series of the mean wave direction. The queried location lies to the south of Nagasaki in the Philippine Sea.https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/mean_wave_direction:d/27.852903,130.116770/html

  

   

• Create a time series of the mean wave direction. The queried location lies to the south of Nagasaki in the Philippine Sea.https://api.meteomatics.com/__replace__0T00:00:00ZPT12H:PT1H/max_individual_wave_height:m/27.852903,130.116770/json

  {"version":"3.0","user":"api-test","dateGenerated":"2018-02-14T16:32:30Z","status":"OK","data":
  [{"parameter":"max_individual_wave_height:m","coordinates":[{"lat":27.8529,"lon":130.117,"dates":
  [{"date":"2017-08-02T00:00:00Z","value":4.8},{"date":"2017-08-02T01:00:00Z","value":4.8},
  {"date":"2017-08-02T02:00:00Z","value":4.9},{"date":"2017-08-02T03:00:00Z","value":4.9},
  {"date":"2017-08-02T04:00:00Z","value":5},{"date":"2017-08-02T05:00:00Z","value":5},
  {"date":"2017-08-02T06:00:00Z","value":5},{"date":"2017-08-02T07:00:00Z","value":5.1},
  {"date":"2017-08-02T08:00:00Z","value":5.1},{"date":"2017-08-02T09:00:00Z","value":5.2},
  {"date":"2017-08-02T10:00:00Z","value":5.2},{"date":"2017-08-02T11:00:00Z","value":5.2},
  {"date":"2017-08-02T12:00:00Z","value":5.3}]}]}]}

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_direction:d/90,-180_-90,180:1000x600/html

  

Maximum Individual Wave Height

From a theory of wave height distribution that includes non-linear effects, the estimation value of the largest single wave height in a record of 20 minutes is derived.

max_individual_wave_height:m

Examples

• Create a time series of the maximal individual wave height. The queried location lies to the south of Nagasaki in the Philippine Sea.https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/max_individual_wave_height:m/27.852903,130.116770/html

  

   

• https://api.meteomatics.com/__replace__0T00:00:00Z/max_individual_wave_height:m/90,-180_-90,180:1000x600/html

  

Mean Direction Wind Waves

Spectral mean direction over all frequencies and direction of the wind waves spectrum.
The wind waves spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are still under the influence of the local wind.
Please note that we are using the meteorological convention to define directions (Read more here).

mean_direction_wind_waves:d

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_direction_wind_waves:d/90,-180_-90,180:1000x600/html

  

• Obtain the values directly in csv format.https://api.meteomatics.com/__replace__0T00:00:00ZP1D:PT2H/mean_direction_wind_waves:d/27.852903,130.116770/csv

  validdate;mean_direction_wind_waves:d
  2017-08-25T00:00:00Z;193.3
  2017-08-25T02:00:00Z;200.5
  2017-08-25T04:00:00Z;202
  2017-08-25T06:00:00Z;197.9
  2017-08-25T08:00:00Z;183.3
  2017-08-25T10:00:00Z;171.9
  2017-08-25T12:00:00Z;163.6
  2017-08-25T14:00:00Z;170.5
  2017-08-25T16:00:00Z;176.2
  2017-08-25T18:00:00Z;180.7
  2017-08-25T20:00:00Z;183.5
  2017-08-25T22:00:00Z;204.1
  2017-08-26T00:00:00Z;242.2

Mean Period Total Swell

Spectral mean wave period obtained using the reciprocal frequency moment of the total swell spectrum. The total swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind.

mean_period_total_swell:s

Examples

• Create a time series showing the mean period of the total swell. The queried location lies in the Philippine Sea south of Nagasaki.https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/mean_period_total_swell:s/27.852903,130.116770/html

  

   

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_period_total_swell:s/90,-180_-90,180:1000x600/html

  

Mean Period Wind waves

Spectral mean wave period obtained using the reciprocal integral moment of the wind waves spectrum. The wind waves spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are under the influence of the local wind. The integration is performed to infinitely high frequencies.

mean_period_wind_waves:s

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_period_wind_waves:s/90,-180_-90,180:1000x600/html

  

Mean Wave Direction First Swell

Spectral mean wave direction computed using the first-most energetic partition of the swell spectrum The swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind.
Please note that we are using the meteorological convention to define directions (Read more here).

mean_wave_direction_first_swell:d

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_direction_first_swell:d/90,-180_-90,180:1000x600/html

  

Mean Wave Direction Second Swell

Spectral mean wave direction computed using the second-most energetic partition of the swell spectrum The swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind.
Please note that we are using the meteorological convention to define directions (Read more here).

mean_wave_direction_second_swell:d

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_direction_second_swell:d/90,-180_-90,180:1000x600/html

  

Mean Wave Direction Third Swell

Spectral mean wave direction computed using the third-most energetic partition of the swell spectrum. The swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind.
Please note that we are using the meteorological convention to define directions (Read more here).

mean_wave_direction_third_swell:d

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_direction_third_swell:d/90,-180_-90,180:1000x600/html

  

Mean Wave Period

Spectral mean wave period obtained using the reciprocal frequency moment of the full wave spectrum. The integration is performed over all theoretical frequencies up to infinity. Again, the frequency wave spectrum is obtained by integrating the two-dimensional wave spectrum over all directions.

mean_wave_period:s

Examples

• Show a time series depicting the mean wave period. The queried location lies in the Philippine Sea south of Nagasaki.https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/mean_wave_period:s/27.852903,130.116770/html

  

   

• A part of the corresponding csv-file.https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/mean_wave_period:s/27.852903,130.116770/csv

  validdate;mean_wave_period:s
  2017-08-03T03:00:00Z;10
  2017-08-03T04:00:00Z;9.9
  2017-08-03T05:00:00Z;9.9
  2017-08-03T06:00:00Z;9.9
  2017-08-03T07:00:00Z;9.9
  2017-08-03T08:00:00Z;10
  2017-08-03T09:00:00Z;10.1
  2017-08-03T10:00:00Z;10.2
  2017-08-03T11:00:00Z;10.3

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_period:s/90,-180_-90,180:1000x600/html

  

Mean Wave Period First Moment

Spectral mean wave period obtained using the first frequency moment of the total swell spectrum. The integration is performed over all theoretical frequencies up to infinity. The frequency wave spectrum is obtained by integrating the two-dimensional wave spectrum over all directions.

mean_wave_period_first_moment:s

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_period_first_moment:s/90,-180_-90,180:1000x600/html

  

Mean Wave Period First Swell

Spectral mean wave period obtained using the first integral moment of the total swell frequency spectrum. The integration is performed over all theoretical frequencies up to infinity. The total swell frequency spectrum is obtained by integrating the two-dimensional wave spectrum over all directions for all wave components that are no longer under the influence of the local wind (full spectrum without wind sea).

mean_wave_period_first_swell:s

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_period_first_swell:s/90,-180_-90,180:1000x600/html

  

Mean Wave Period Second Moment

Spectral mean wave period obtained using the second integral moment of the frequency wave spectrum. The integration is performed over all theoretical frequencies up to infinity. The frequency wave spectrum is obtained by integrating the two-dimensional wave spectrum over all directions.

mean_wave_period_second_moment:s

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_period_second_moment:s/90,-180_-90,180:1000x600/html

  

Mean Wave Period Second Swell

Spectral mean wave period obtained using the second integral moment of the total swell frequency spectrum. The integration is performed over all theoretical frequencies up to infinity. The total swell frequency spectrum is obtained by integrating the two-dimensional wave spectrum over all directions for all wave components that are not under the influence of the local wind (full spectrum without wind sea).

mean_wave_period_second_swell:s

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_period_second_swell:s/90,-180_-90,180:1000x600/html

  

Mean Wave Period Third Swell

Mean wave period computed using the reciprocal frequency moment of the third most energetic partition of the swell spectrum.
The swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind (full spectrum without wind sea).

mean_wave_period_third_swell:s

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/mean_wave_period_third_swell:s/90,-180_-90,180:1000x600/html

  

Significant Height Total Swell

4 times the square root of the integral over all directions and all frequencies of the total swell spectrum. The total swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind.

significant_height_total_swell:m

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/significant_height_total_swell:m/90,-180_-90,180:1000x600/html

  

Significant Height Wind Waves

4 times the square root of the integral over all directions and all frequencies of the windsea wave spectrum. The wind waves spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are under the influence of the local wind (wind sea).

significant_height_wind_waves:m

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/significant_height_wind_waves:m/90,-180_-90,180:1000x600/html

  

Significant Wave Height First Swell

Significant wave height for the first most energetic partition of the swell spectrum (as determined by ECMWF),
where the significant wave height is defined as 4 times the square root of the integral
over all directions and all frequencies of the first partition of the swell spectrum.
The swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind.

significant_wave_height_first_swell:m

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/significant_wave_height_first_swell:m/90,-180_-90,180:1000x600/html

  

• https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/significant_wave_height_first_swell:m/27.852903,130.116770/html

  

Significant Wave Height Second Swell

Significant wave height for the second most energetic partition of the swell spectrum (as determined by ECMWF),
where the significant wave height is defined as 4 times the square root of the integral
over all directions and all frequencies of the second partition of the swell spectrum.
The swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind.

significant_wave_height_second_swell:m

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/significant_wave_height_second_swell:m/90,-180_-90,180:1000x600/html

  

• https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/significant_wave_height_second_swell:m/27.852903,130.116770/html

  

• https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/significant_wave_height_second_swell:m/27.852903,130.116770/csv

  validdate;significant_wave_height_second_swell:m
  2018-03-01T07:00:00Z;0.7
  2018-03-01T08:00:00Z;0.9
  2018-03-01T09:00:00Z;1.1
  2018-03-01T10:00:00Z;1.3
  2018-03-01T11:00:00Z;1.5
  2018-03-01T12:00:00Z;1.7
  2018-03-01T13:00:00Z;1.6
  2018-03-01T14:00:00Z;1.5
  2018-03-01T15:00:00Z;1.4
  2018-03-01T16:00:00Z;1.3

Significant Wave Height Third Swell

Significant wave height for the third most energetic partition of the swell spectrum (as determined by ECMWF),
where the significant wave height is defined as 4 times the square root of the integral
over all directions and all frequencies of the third partition of the swell spectrum.
The swell spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are not under the influence of the local wind.

significant_wave_height_third_swell:m

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/significant_wave_height_third_swell:m/90,-180_-90,180:1000x600/html

  

• https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/significant_wave_height_third_swell:m/27.852903,130.116770/html

  

Stokes Drift

For a pure wave motion in fluid dynamics, the Stokes drift velocity is the average velocity of a specific fluid parcel as it travels with the fluid flow. For instance, a particle floating at the free surface of water waves experiences a net Stokes drift velocity in the direction of wave propagation. Along with effects such as Ekman drift and geostrophic currents, the Stokes drift is one of the most relevant processes in the transport of marine debris.
Please note that we are using the meteorological convention to define directions (Read more here).

Speed and direction:

stokes_drift_speed:<speed_unit>
stokes_drift_dir:d

Components (u is positive for a west to east flow, v is positive for a south to north flow ):

stokes_drift_speed_u:<speed_unit>
stokes_drift_speed_v:<speed_unit>

Available speed units: ms, kmh, kn

Examples

• https://api.meteomatics.com/__replace__0T00:00:00Z/stokes_drift_speed_u:ms/90,-180_-90,180:1000x600/html

  

• https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/stokes_drift_speed_u:ms/27.852903,130.116770/html

  

• https://api.meteomatics.com/__replace__0T00:00:00Z/stokes_drift_speed_v:ms/90,-180_-90,180:1000x600/html (upper right)

  

• https://api.meteomatics.com/__replace__0T00:00:00ZP3D:PT1H/stokes_drift_speed_v:ms/27.852903,130.116770/html (lower right)

  

Ocean Current

These parameters describe the velocity of the ocean currents.
Please note that we are using the meteorological convention to define directions (Read more here).

Speed and direction (surface level):

ocean_current_speed:<speed_unit>
ocean_current_direction:d

Components (surface level, u is positive for a west to east flow, v is positive for a south to north flow):

ocean_current_u:<speed_unit>
ocean_current_v:<speed_unit>

Speed and direction (submarine levels):

ocean_current_speed_<level>:<speed_unit>
ocean_current_direction_<level>:d

Components (submarine levels, u is positive for a west to east flow, v is positive for a south to north flow):

ocean_current_u_<level>:<speed_unit>
ocean_current_v_<level>:<speed_unit>

Available levels: 2m, 4m, 6m, 8m, 10m, 12m, 15m, 20m, 50m, 100m 1000m (below mean sea level)

Available speed units: ms, kmh, kn

Example

Water speed in 10m depth on a straight line from New York to Lisbon

• https://api.meteomatics.com/__replace__0T12Z/ocean_current_speed_10m:ms/37.2700358,-74.2856509_38.5162836,-9.218927:1000/csv

  

Water Temperature

The temperature of the water.

Surface temperature:

water_temperature:C

Example

A cross section of the temperature in the Atlantic at -30° longitude from 60° to -70 degrees latitude.

• https://api.meteomatics.com/__replace__0T12Z/water_temperature:C/60,-30_-70,-30:1000/csv

  

• https://api.meteomatics.com/__replace__0T12Z/water_temperature:C/60,-30_-70,-30:10/csv

  lat;lon;validdate;water_temperature:C
  60;-30;2018-01-01T12:00:00Z;6.9
  45.5556;-30;2018-01-01T12:00:00Z;14
  31.1111;-30;2018-01-01T12:00:00Z;21.3
  16.6667;-30;2018-01-01T12:00:00Z;24.6
  2.22222;-30;2018-01-01T12:00:00Z;26.4
  -12.2222;-30;2018-01-01T12:00:00Z;26.8
  -26.6667;-30;2018-01-01T12:00:00Z;22.2
  -41.1111;-30;2018-01-01T12:00:00Z;14.1
  -55.5556;-30;2018-01-01T12:00:00Z;1.4
  -70;-30;2018-01-01T12:00:00Z;-0

Salinity

The amount of salt within the water.

Surface salinity:

salinity:psu

Example

• https://api.meteomatics.com/__replace__0T00Z/salinity:psu/80,-180_-80,180:0.2,0.2/png

Bathymetry

The depth of the ocean for each point on earth.

Ocean depth:

ocean_depth:<unit>

Available units: m, km, ft

Example

Global ocean depth as an image:

• https://api.meteomatics.com/__replace__0T00Z/ocean_depth:m/80,-180_-80,180:0.4,0.4/png

Ocean depth through the north atlantic at latitude 50, from longitude -60 to 0:

• https://api.meteomatics.com/__replace__0T00Z/ocean_depth:m/50,-60_50,0:10/csv

  lat;lon;validdate;ocean_depth:m
  50;-60;2018-05-01T00:00:00Z;132.8
  50;-53.3333;2018-05-01T00:00:00Z;322.6
  50;-46.6667;2018-05-01T00:00:00Z;3007.1
  50;-40;2018-05-01T00:00:00Z;4345.0
  50;-33.3333;2018-05-01T00:00:00Z;3678.9
  50;-26.6667;2018-05-01T00:00:00Z;3670.5
  50;-20;2018-05-01T00:00:00Z;4418.3
  50;-13.3333;2018-05-01T00:00:00Z;2659.4
  50;-6.66667;2018-05-01T00:00:00Z;96.7
  50;0;2018-05-01T00:00:00Z;43.3

1. Wikipedia Page of Significant Wave Height: http://en.wikipedia.org/wiki/Significant_wave_height
2. National Hurricane Center: http://www.nhc.noaa.gov/pdf/TAFB_wave_period.pdf