Ocean Wave Model high resolution 10-day Forecast (Set II - HRES-WAM)

Configure and order Set II

HRES-WAM (High RESolution WAve Model) is coupled to the atmospheric model (HRES) and it is a Direct model output Products offers "High Frequency products":

  • 4 forecast runs per day (00/06/12/18) (see dissemination schedule for details)
  • Hourly steps to step 90 for all four runs

Domain

  • HRES-WAM: Global

The  model computes between the latitudes -78 and 90, the output grid is artificially extended to -90.

The purchase of the "Basic Set" +72, +96, +120, +144, +168 hrs is a mandatory prerequisite for the purchase of time steps in the range 12 to 66 hours.

Product description

Resolution supported

  • 0.125° x 0.125° lat/long grid or any multiple thereof (global or sub-area)
  • 0.1° x 0.1° lat/lon or any multiple thereof (global or sub-area)

 

Single level -forecast - HRES-WAM

  Forecast time step Base time
T+0 to T+90 1-hourly 00 UTC, 06 UTC, 12 UTC and 18UTC
T+93 to T+144 3-hourly 00 UTC and 12 UTC
T+150h to T+240h 6-hourly 00 UTC and 12 UTC

 

Dissemination schedule

HRES-WAM

Forecast Runs (base time) Forecast step frequency Forecast Dissemination schedule Forecast Dissemination stream indicator
00 UTC
  • 0 to 90 by 1
  • 93  to 144 by 3
  • 150 to 240 by 6
  • 5:45 --> 6:13
  • 6:13 --> 6:27
  • 6:27 --> 6:55
  • Q
  • P
  • P
06 UTC
  • 0 to 90 by 1
  • 11:45 --> 12:13
  • Q
12 UTC
  • 0 to 90 by 1
  • 0 to 144 by 3
  • 150 to 240 by 6
  • 17:45 --> 18:13
  • 18:13 --> 18:27
  • 18:27 --> 18:55
  • Q
  • P
  • P
18 UTC
  • 0 to 90 by 1
  • 23:45 --> 00:13
  • Q
Short Name ID Long Name Description Units Additional information
weta 140098 Wave induced mean sea level correction   m  
wraf 140099 Ratio of wave angular and frequency width   dimensionless  
wnslc 140100 Number of events in freak waves statistics   dimensionless  
utaua 140101 U-component of atmospheric surface momentum flux   N m**-2  
vtaua 140102 V-component of atmospheric surface momentum flux   N m**-2  
utauo 140103 U-component of surface momentum flux into ocean   N m**-2  
vtauo 140104 V-component of surface momentum flux into ocean   N m**-2  
wphio 140105 Wave turbulent energy flux into ocean   W m**-2  
wefxm 140112 Wave energy flux magnitude This parameter is the amount of energy from ocean/sea waves which are generated by local winds and associated with swell. It is the magnitude of the energy flux per unit length of wave crest, also known as the wave power per unit length of wave crest.

In deep water, the wave energy flux magnitude can be estimated from the mean wave period and the significant wave height. In the ECMWF Integrated Forecasting System, it is calculated by integrating the full two-dimensional wave spectrum multiplied by the wave group velocity (the velocity of the envelope of a group of waves of nearly equal frequencies).
W m**-1  
wefxd 140113 Wave energy flux mean direction This parameter is the direction of the flux of energy of ocean/sea waves which are generated by local winds and associated with swell.

It is the spectral mean direction calculated by integrating the full two-dimensional wave energy spectrum multiplied by the wave group velocity (the velocity of the envelope of a group of waves of nearly equal frequencies).

The units are degrees true which means the direction relative to the geographic location of the north pole. It is the direction that waves are coming FROM, so zero means 'coming from the north' and 90 'coming from the east'.
Degree true  
h1012 140114 Significant wave height of all waves with periods within the inclusive range from 10 to 12 seconds This parameter represents the average height of the highest third of surface ocean/sea waves that have a period between 10 and 12 seconds. It includes all waves generated by local winds and associated with swell. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

More strictly, this parameter is four times the square root of the integral over all directions of the two-dimensional wave spectrum and all frequencies between 1/12 and 1/10 hertz (i.e. periods between 10 and 12 seconds). See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
h1214 140115 Significant wave height of all waves with periods within the inclusive range from 12 to 14 seconds This parameter represents the average height of the highest third of surface ocean/sea waves that have a period between 12 and 14 seconds. It includes all waves generated by local winds and associated with swell. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

More strictly, this parameter is four times the square root of the integral over all directions of the two-dimensional wave spectrum and all frequencies between 1/14 and 1/12 hertz (i.e. periods between 12 and 14 seconds). See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
h1417 140116 Significant wave height of all waves with periods within the inclusive range from 14 to 17 seconds This parameter represents the average height of the highest third of surface ocean/sea waves that have a period between 14 and 17 seconds. It includes all waves generated by local winds and associated with swell. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

More strictly, this parameter is four times the square root of the integral over all directions of the two-dimensional wave spectrum and all frequencies between 1/17 and 1/14 hertz (i.e. periods between 14 and 17 seconds). See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
h1721 140117 Significant wave height of all waves with periods within the inclusive range from 17 to 21 seconds This parameter represents the average height of the highest third of surface ocean/sea waves that have a period between 17 and 21 seconds. It includes all waves generated by local winds and associated with swell. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

More strictly, this parameter is four times the square root of the integral over all directions of the two-dimensional wave spectrum and all frequencies between 1/21 and 1/17 hertz (i.e. periods between 17 and 21 seconds). See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
h2125 140118 Significant wave height of all waves with periods within the inclusive range from 21 to 25 seconds This parameter represents the average height of the highest third of surface ocean/sea waves that have a period between 21 and 25 seconds. It includes all waves generated by local winds and associated with swell. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

More strictly, this parameter is four times the square root of the integral over all directions of the two-dimensional wave spectrum and all frequencies between 1/25 and 1/21 hertz (i.e. periods between 21 and 25 seconds). See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
h2530 140119 Significant wave height of all waves with periods within the inclusive range from 25 to 30 seconds This parameter represents the average height of the highest third of surface ocean/sea waves that have a period between 25 and 30 seconds. It includes all waves generated by local winds and associated with swell. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

More strictly, this parameter is four times the square root of the integral over all directions of the two-dimensional wave spectrum and all frequencies between 1/30 and 1/25 hertz (i.e. periods between 25 and 30 seconds). See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
sh10 140120 Significant wave height of all waves with period larger than 10s This parameter represents the average height of the highest third of surface ocean/sea waves that have a period of longer than 10 seconds. It includes all waves generated by local winds and associated with swell. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

More strictly, this parameter is four times the square root of the integral over all directions of the two-dimensional wave spectrum and over frequencies less than 0.1 hertz (i.e. periods longer than 10 seconds). See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
swh1 140121 Significant wave height of first swell partition This parameter represents the average height of the highest third of surface ocean/sea waves associated with the first swell partition. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

In many situations, swell can be made up of different swell systems, for example, from two distant and separate storms. To account for this, the swell spectrum is partitioned into up to three parts. The swell partitions are labelled first, second and third based on their respective wave height. Therefore, there is no guarantee of spatial coherence (the first might be from one system at one location and another system at the neighbouring location). See further information.

More strictly, this parameter is four times the square root of the integral over all directions and all frequencies of the first swell partition of the two-dimensional 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.

This parameter can be used to assess swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
mwd1 140122 Mean wave direction of first swell partition This parameter is the mean direction of waves in the first swell partition.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

In many situations, swell can be made up of different swell systems, for example, from two distant and separate storms. To account for this, the swell spectrum is partitioned into up to three parts. The swell partitions are labelled first, second and third based on their respective wave height. Therefore, there is no guarantee of spatial coherence (the first swell partition might be from one system at one location and a different system at the neighbouring location). See further information.

The units are degrees true which means the direction relative to the geographic location of the north pole. It is the direction that waves are coming FROM, so zero means 'coming from the north' and 90 'coming from the east'.
degrees  
mwp1 140123 Mean wave period of first swell partition This parameter is the mean period of waves in the first swell partition. The wave period is the average time it takes for two consecutive wave crests, on the surface of the ocean/sea, to pass through a fixed point.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

In many situations, swell can be made up of different swell systems, for example, from two distant and separate storms. To account for this, the swell spectrum is partitioned into up to three parts. The swell partitions are labelled first, second and third based on their respective wave height. Therefore, there is no guarantee of spatial coherence (the first swell partition might be from one system at one location and a different system at the neighbouring location). See further information.
s  
swh2 140124 Significant wave height of second swell partition This parameter represents the average height of the highest third of surface ocean/sea waves associated with the second swell partition. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

In many situations, swell can be made up of different swell systems, for example, from two distant and separate storms. To account for this, the swell spectrum is partitioned into up to three parts. The swell partitions are labelled first, second and third based on their respective wave height. Therefore, there is no guarantee of spatial coherence (the second might be from one system at one location and another system at the neighbouring location). See further information.

More strictly, this parameter is four times the square root of the integral over all directions and all frequencies of the first swell partition of the two-dimensional 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.

This parameter can be used to assess swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
mwd2 140125 Mean wave direction of second swell partition This parameter is the mean direction of waves in the second swell partition.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

In many situations, swell can be made up of different swell systems, for example, from two distant and separate storms. To account for this, the swell spectrum is partitioned into up to three parts. The swell partitions are labelled first, second and third based on their respective wave height. Therefore, there is no guarantee of spatial coherence (the second swell partition might be from one system at one location and a different system at the neighbouring location). See further information.

The units are degrees true which means the direction relative to the geographic location of the north pole. It is the direction that waves are coming FROM, so zero means 'coming from the north' and 90 'coming from the east'.
degrees  
mwp2 140126 Mean wave period of second swell partition This parameter is the mean period of waves in the second swell partition. The wave period is the average time it takes for two consecutive wave crests, on the surface of the ocean/sea, to pass through a fixed point.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

In many situations, swell can be made up of different swell systems, for example, from two distant and separate storms. To account for this, the swell spectrum is partitioned into up to three parts. The swell partitions are labelled first, second and third based on their respective wave height. Therefore, there is no guarantee of spatial coherence (the second swell partition might be from one system at one location and a different system at the neighbouring location). See further information.
s  
swh3 140127 Significant wave height of third swell partition This parameter represents the average height of the highest third of surface ocean/sea waves associated with the third swell partition. Wave height represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

In many situations, swell can be made up of different swell systems, for example, from two distant and separate storms. To account for this, the swell spectrum is partitioned into up to three parts. The swell partitions are labelled first, second and third based on their respective wave height. Therefore, there is no guarantee of spatial coherence (the third might be from one system at one location and another system at the neighbouring location). See further information.

More strictly, this parameter is four times the square root of the integral over all directions and all frequencies of the first swell partition of the two-dimensional 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.

This parameter can be used to assess swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
mwd3 140128 Mean wave direction of third swell partition This parameter is the mean direction of waves in the third swell partition.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

In many situations, swell can be made up of different swell systems, for example, from two distant and separate storms. To account for this, the swell spectrum is partitioned into up to three parts. The swell partitions are labelled first, second and third based on their respective wave height. Therefore, there is no guarantee of spatial coherence (the third swell partition might be from one system at one location and a different system at the neighbouring location). See further information.

The units are degrees true which means the direction relative to the geographic location of the north pole. It is the direction that waves are coming FROM, so zero means 'coming from the north' and 90 'coming from the east'.
degrees  
mwp3 140129 Mean wave period of third swell partition This parameter is the mean period of waves in the third swell partition. The wave period is the average time it takes for two consecutive wave crests, on the surface of the ocean/sea, to pass through a fixed point.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.

In many situations, swell can be made up of different swell systems, for example, from two distant and separate storms. To account for this, the swell spectrum is partitioned into up to three parts. The swell partitions are labelled first, second and third based on their respective wave height. Therefore, there is no guarantee of spatial coherence (the third swell partition might be from one system at one location and a different system at the neighbouring location). See further information.
s  
wss 140207 Wave Spectral Skewness This parameter is a statistical measure used to forecast extreme or freak ocean/sea waves. It describes the nature of the sea surface elevation and how it is affected by waves generated by local winds and associated with swell.

Under typical conditions, the sea surface elevation, as described by its probability density function, has a near normal distribution in the statistical sense. However, under certain wave conditions the probability density function of the sea surface elevation can deviate considerably from normality, signalling increased probability of freak waves.

This parameter gives one measure of the deviation from normality. It is a measure of the asymmetry of the probability density function of the sea surface elevation. So, a positive/negative skewness (typical range -0.2 to 0.12) means more frequent occurrences of extreme values above/below the mean, relative to a normal distribution.
dimensionless  
wstar 140208 Free convective velocity over the oceans This parameter is an estimate of the vertical velocity of updraughts generated by free convection. Free convection is fluid motion induced by buoyancy forces, which are driven by density gradients. The free convective velocity is used to estimate the impact of wind gusts on ocean wave growth.

It is calculated at the height of the lowest temperature inversion (the height above the surface of the Earth where the temperature increases with height).

This parameter is one of the parameters used to force the wave model, therefore it is only calculated over water bodies represented in the ocean wave model. It is interpolated from the atmospheric model horizontal grid onto the horizontal grid used by the ocean wave model.
m s**-1  
rhoao 140209 Air density over the oceans This parameter is the mass of air per cubic metre over the oceans, derived from the temperature, specific humidity and pressure at the lowest model level in the atmospheric model.

This parameter is one of the parameters used to force the wave model, therefore it is only calculated over water bodies represented in the ocean wave model. It is interpolated from the atmospheric model horizontal grid onto the horizontal grid used by the ocean wave model.
kg m**-3  
phiaw 140211 Normalized energy flux into waves This parameter is the normalised vertical flux of energy from wind into the ocean waves. A positive flux implies a flux into the waves.

The energy flux has units of Watts per metre squared, and this is normalised by being divided by the product of air density and the cube of the friction velocity.
dimensionless  
phioc 140212 Normalized energy flux into ocean This parameter is the normalised vertical flux of turbulent kinetic energy from ocean waves into the ocean. The energy flux is calculated from an estimation of white capping waves across the surface of the ocean. A white capping wave is one that appears white at its crest as it breaks, due to air being mixed into the water. When waves break in this way, there is a transfer of energy from the waves to the ocean. A negative flux implies a flux from the waves into the ocean.

The energy flux has units of Watts per metre squared, and this is normalised by being divided by the product of air density and the cube of the friction velocity.
dimensionless  
tauoc 140214 Normalized stress into ocean This parameter is the normalised surface stress, or momentum flux, from the air into the ocean due to turbulence at the air-sea interface and breaking waves. It does not include the flux used to generate waves. The ECMWF convention for vertical fluxes is positive downwards.

The stress has units of Newtons per metre squared, and this is normalised by being divided by the product of air density and the square of the friction velocity.
dimensionless  
ust 140215 U-component stokes drift This parameter is the eastward component of the surface Stokes drift. The Stokes drift is the net drift velocity due to surface wind waves. It is confined to the upper few metres of the ocean water column, with the largest value at the surface.

For example, a fluid particle near the surface will slowly move in the direction of wave propagation.
m s**-1  
vst 140216 V-component stokes drift This parameter is the northward component of the surface Stokes drift. The Stokes drift is the net drift velocity due to surface wind waves. It is confined to the upper few metres of the ocean water column, with the largest value at the surface.

For example, a fluid particle near the surface will slowly move in the direction of wave propagation.
m s**-1  
tmax 140217 Period corresponding to maximum individual wave height This parameter is the period of the expected highest individual wave within a 20-minute time window. It can be used as a guide to the characteristics of extreme or freak waves. Wave period is the average time it takes for two consecutive wave crests, on the surface of the ocean/sea, to pass through a fixed point.

Occasionally waves of different periods reinforce and interact non-linearly giving a wave height considerably larger than the significant wave height. If the maximum individual wave height is more than twice the significant wave height, then the wave is considered to be a freak wave. The significant wave height represents the average height of the highest third of surface ocean/sea waves, generated by local winds and associated with swell.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). This parameter is derived statistically from the two-dimensional wave spectrum. See further information.

The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of both.
s  
hmax 140218 Maximum individual wave height This parameter is an estimate of the height of the expected highest individual wave within a 20 minute time window. It can be used as a guide to the likelihood of extreme or freak waves.

The interactions between waves are non-linear and occasionally concentrate wave energy giving a wave height considerably larger than the significant wave height. If the maximum individual wave height is more than twice the significant wave height, then the wave is considered as a freak wave. The significant wave height represents the average height of the highest third of surface ocean/sea waves, generated by local winds and associated with swell.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). This parameter is derived statistically from the two-dimensional wave spectrum. See further information.

The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of both.
m  
wmb 140219 Model bathymetry This parameter is the depth of water from the surface to the bottom of the ocean. It is used by the ocean wave model to specify the propagation properties of the different waves that could be present.

Note that the ocean wave model grid is too coarse to resolve some small islands and mountains on the bottom of the ocean, but they can have an impact on surface ocean waves. The ocean wave model has been modified to reduce the wave energy flowing around or over features at spatial scales smaller than the grid box.
m  
mp1 140220 Mean wave period based on first moment This parameter is the reciprocal of the mean frequency of the wave components that represent the sea state. All wave components have been averaged proportionally to their respective amplitude. This parameter can be used to estimate the magnitude of Stokes drift transport in deep water.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). Moments are statistical quantities derived from the two-dimensional wave spectrum.
s  
mp2 140221 Mean zero-crossing wave period This parameter represents the mean length of time between occasions where the sea/ocean surface crosses mean sea level. In combination with wave height information, it could be used to assess the length of time that a coastal structure might be under water, for example.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). In the ECMWF Integrated Forecasting System this parameter is calculated from the characteristics of the two-dimensional wave spectrum.
s  
wdw 140222 Wave spectral directional width This parameter indicates whether waves (generated by local winds and associated with swell) are coming from similar directions or from a wide range of directions.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). Many ECMWF wave parameters (such as the mean wave period) give information averaged over all wave frequencies and directions, so do not give any information about the distribution of wave energy across frequencies and directions. This parameter gives more information about the nature of the two-dimensional wave spectrum. This parameter is a measure of the range of wave directions for each frequency integrated across the two-dimensional spectrum.

This parameter takes values between 0 and the square root of 2. Where 0 corresponds to a uni-directional spectrum (i.e., all wave frequencies from the same direction) and the square root of 2 indicates a uniform spectrum (i.e., all wave frequencies from a different direction).
dimensionless  
p1ww 140223 Mean wave period based on first moment for wind waves This parameter is the reciprocal of the mean frequency of the wave components generated by local winds. All wave components have been averaged proportionally to their respective amplitude. This parameter can be used to estimate the magnitude of Stokes drift transport in deep water associated with wind waves.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.This parameter takes account of wind-sea waves only. Moments are statistical quantities derived from the two-dimensional wave spectrum.
s  
p2ww 140224 Mean wave period based on second moment for wind waves This parameter is equivalent to the zero-crossing mean wave period for waves generated by local winds. The zero-crossing mean wave period represents the mean length of time between occasions where the sea/ocean surface crosses a defined zeroth level (such as mean sea level).

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. Moments are statistical quantities derived from the two-dimensional wave spectrum.
s  
dwww 140225 Wave spectral directional width for wind waves This parameter indicates whether waves generated by the local wind are coming from similar directions or from a wide range of directions.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of wind-sea waves only.

Many ECMWF wave parameters (such as the mean wave period) give information averaged over all wave frequencies and directions, so do not give any information about the distribution of wave energy across frequencies and directions. This parameter gives more information about the nature of the two-dimensional wave spectrum. This parameter is a measure of the range of wave directions for each frequency integrated across the two-dimensional spectrum.

This parameter takes values between 0 and the square root of 2. Where 0 corresponds to a uni-directional spectrum (i.e., all wave frequencies from the same direction) and the square root of 2 indicates a uniform spectrum (i.e., all wave frequencies from a different direction).
dimensionless  
p1ps 140226 Mean wave period based on first moment for swell This parameter is the reciprocal of the mean frequency of the wave components associated with swell. All wave components have been averaged proportionally to their respective amplitude. This parameter can be used to estimate the magnitude of Stokes drift transport in deep water associated with swell.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.This parameter takes account of all swell only. Moments are statistical quantities derived from the two-dimensional wave spectrum.
s  
p2ps 140227 Mean wave period based on second moment for swell This parameter is equivalent to the zero-crossing mean wave period for swell. The zero-crossing mean wave period represents the mean length of time between occasions where the sea/ocean surface crosses a defined zeroth level (such as mean sea level).

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. Moments are statistical quantities derived from the two-dimensional wave spectrum.
s  
dwps 140228 Wave spectral directional width for swell This parameter indicates whether waves associated with swell are coming from similar directions or from a wide range of directions.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of all swell only.

Many ECMWF wave parameters (such as the mean wave period) give information averaged over all wave frequencies and directions, so do not give any information about the distribution of wave energy across frequencies and directions. This parameter gives more information about the nature of the two-dimensional wave spectrum. This parameter is a measure of the range of wave directions for each frequency integrated across the two-dimensional spectrum.

This parameter takes values between 0 and the square root of 2. Where 0 corresponds to a uni-directional spectrum (i.e., all wave frequencies from the same direction) and the square root of 2 indicates a uniform spectrum (i.e., all wave frequencies from a different direction).
dimensionless  
swh 140229 Significant height of combined wind waves and swell This parameter represents the average height of the highest third of surface ocean/sea waves generated by wind and swell. It represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum).

The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of both.

More strictly, this parameter is four times the square root of the integral over all directions and all frequencies of the two-dimensional wave spectrum. See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
mwd 140230 Mean wave direction This parameter is the mean direction of ocean/sea surface waves. The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). This parameter is a mean over all frequencies and directions of the two-dimensional wave spectrum.

The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of both. See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use this type of wave information when designing structures in the open ocean, such as oil platforms, or in coastal applications.

The units are degree true which means the direction relative to the geographic location of the north pole. Zero means 'coming from the north' and 90 'coming from the east'.
Degree true  
pp1d 140231 Peak wave period This parameter represents the period of the most energetic ocean waves generated by local winds and associated with swell. The wave period is the average time it takes for two consecutive wave crests, on the surface of the ocean/sea, to pass through a fixed point.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). This parameter is calculated from the reciprocal of the frequency corresponding to the largest value (peak) of the frequency wave spectrum. The frequency wave spectrum is obtained by integrating the two-dimensional wave spectrum over all directions.

The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of both.
s  
mwp 140232 Mean wave period This parameter is the average time it takes for two consecutive wave crests, on the surface of the ocean/sea, to pass through a fixed point. The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). This parameter is a mean over all frequencies and directions of the two-dimensional wave spectrum.

The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of both. See further documentation.

This parameter can be used to assess sea state and swell. For example, engineers use such wave information when designing structures in the open ocean, such as oil platforms, or in coastal applications.
s  
cdww 140233 Coefficient of drag with waves This parameter is the resistance that ocean waves exert on the atmosphere. It is sometimes also called a 'friction coefficient'.

It is calculated by the wave model as the ratio of the square of the friction velocity, to the square of the neutral wind speed at a height of 10 metres above the surface of the Earth.

The neutral wind is calculated from the surface stress and the corresponding roughness length by assuming that the air is neutrally stratified. The neutral wind is, by definition, in the direction of the surface stress. The size of the roughness length depends on the sea state.
dimensionless  
shww 140234 Significant height of wind waves This parameter represents the average height of the highest third of surface ocean/sea waves generated by the local wind. It represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of wind-sea waves only.

More strictly, this parameter is four times the square root of the integral over all directions and all frequencies of the two-dimensional wind-sea wave spectrum. The wind-sea wave spectrum is obtained by only considering the components of the two-dimensional wave spectrum that are still under the influence of the local wind. See further documentation.

This parameter can be used to assess wind-sea waves. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
mdww 140235 Mean direction of wind waves The mean direction of waves generated by local winds.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.This parameter takes account of wind-sea waves only. It is the mean over all frequencies and directions of the total wind-sea wave spectrum. See further information.

The units are degrees true which means the direction relative to the geographic location of the north pole. It is the direction that waves are coming FROM, so zero means 'coming from the north' and 90 'coming from the east'.
degrees  
mpww 140236 Mean period of wind waves This parameter is the average time it takes for two consecutive wave crests, on the surface of the ocean/sea generated by local winds, to pass through a fixed point.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of wind-sea waves only. It is the mean over all frequencies and directions of the total wind-sea spectrum. See further information.
s  
shts 140237 Significant height of total swell This parameter represents the average height of the highest third of surface ocean/sea waves associated with swell. It represents the vertical distance between the wave crest and the wave trough.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of total swell only.

More strictly, this parameter is four times the square root of the integral over all directions and all frequencies of the two-dimensional 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. See further documentation.

This parameter can be used to assess swell. For example, engineers use significant wave height to calculate the load on structures in the open ocean, such as oil platforms, or in coastal applications.
m  
mdts 140238 Mean direction of total swell This parameter is the mean direction of waves associated with swell.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time.This parameter takes account of all swell only. It is the mean over all frequencies and directions of the total swell spectrum. See further information.

The units are degrees true which means the direction relative to the geographic location of the north pole. It is the direction that waves are coming FROM, so zero means 'coming from the north' and 90 'coming from the east'.
degrees  
mpts 140239 Mean period of total swell This parameter is the average time it takes for two consecutive wave crests, on the surface of the ocean/sea associated with swell, to pass through a fixed point.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). The wave spectrum can be decomposed into wind-sea waves, which are directly affected by local winds, and swell, the waves that were generated by the wind at a different location and time. This parameter takes account of all swell only. It is the mean over all frequencies and directions of the total swell spectrum. See further information.
s  
msqs 140244 Mean square slope of waves This parameter can be related analytically to the average slope of combined wind-sea and swell waves. It can also be expressed as a function of wind speed under some statistical assumptions. The higher the slope, the steeper the waves. This parameter indicates the roughness of the sea/ocean surface which affects the interaction between ocean and atmosphere. See further information.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). This parameter is derived statistically from the two-dimensional wave spectrum.
dimensionless  
wind 140245 10 metre wind speed This parameter is the horizontal speed of the 'neutral wind', at a height of ten metres above the surface of the Earth. The units of this parameter are metres per second.

The neutral wind is calculated from the surface stress and the corresponding roughness length by assuming that the air is neutrally stratified. The neutral wind is, by definition, in the direction of the surface stress. The size of the roughness length depends on sea state.

This parameter is the wind speed used to force the wave model, therefore it is only calculated over water bodies represented in the ocean wave model. It is interpolated from the atmospheric model's horizontal grid onto the horizontal grid used by the ocean wave model.
m s**-1  
dwi 140249 10 metre wind direction This parameter is the direction from which the 'neutral wind' blows, in degrees clockwise from true north, at a height of ten metres above the surface of the Earth.

The neutral wind is calculated from the surface stress and roughness length by assuming that the air is neutrally stratified. The neutral wind is, by definition, in the direction of the surface stress. The size of the roughness length depends on the sea state.

This parameter is the wind direction used to force the wave model, therefore it is only calculated over water bodies represented in the ocean wave model. It is interpolated from the atmospheric model's horizontal grid onto the horizontal grid used by the ocean wave model.
degrees  
2dfd 140251 2D wave spectra (single) The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). This parameter represents the wave energy for each frequency and direction at each model grid point i.e., it describes the contribution to the frequency and direction of the two-dimensional wave spectrum.

Strictly, this parameter is the base ten logarithm of the spectral density of ocean waves in two dimensions (across the horizontal surface of the ocean). Therefore, all values (except missing data) need to be raised to the power of ten to give the spectral density. 'Missing data' is indicated by a value of 0. The spectral density describes the combination of waves with different heights, lengths and directions. See further documentation.
m**2 s radian**-1  
wsk 140252 Wave spectral kurtosis This parameter is a statistical measure used to forecast extreme or freak ocean/sea waves. It describes the nature of the sea surface elevation and how it is affected by waves generated by local winds and associated with swell.

Under typical conditions, the sea surface elevation, as described by its probability density function, has a near normal distribution in the statistical sense. However, under certain wave conditions the probability density function of the sea surface elevation can deviate considerably from normality, signalling increased probability of freak waves.

This parameter gives one measure of the deviation from normality. It shows how much of the probability density function of the sea surface elevation exists in the tails of the distribution. So, a positive kurtosis (typical range 0.0 to 0.06) means more frequent occurrences of very extreme values (either above or below the mean), relative to a normal distribution.
dimensionless  
bfi 140253 Benjamin-Feir index This parameter is used to calculate the likelihood of freak ocean waves, which are waves that are higher than twice the mean height of the highest third of waves. Large values of this parameter (in practice of the order 1) indicate increased probability of the occurrence of freak waves.

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). This parameter is derived from the statistics of the two-dimensional wave spectrum. More precisely, it is the square of the ratio of the integral ocean wave steepness and the relative width of the frequency spectrum of the waves.

Further information on the calculation of this parameter is given in Section 10.6 of the ECMWF Wave Model documentation.
dimensionless  
wsp 140254 Wave spectral peakedness This parameter is a statistical measure used to forecast extreme or freak waves. It is a measure of the relative width of the ocean/sea wave frequency spectrum (i.e., whether the ocean/sea wave field is made up of a narrow or broad range of frequencies).

The ocean/sea surface wave field consists of a combination of waves with different heights, lengths and directions (known as the two-dimensional wave spectrum). When the wave field is more focussed around a narrow range of frequencies, the probability of freak/extreme waves increases.

This parameter is Goda's peakedness factor and is used to calculate the Benjamin-Feir Index (BFI). The BFI is in turn used to estimate the probability and nature of extreme/freak waves.
dimensionless  

Last updated 09-09-2020

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Type: 
Real-time
Range: 
Medium (15 days)