GribStream

ECMWF Integrated Forecasting System Wave Ensemble Forecast (IFS Waef)

GribStream Code: ifswaef

Description

The IFS Wave Ensemble Forecast (IFS Waef) is ECMWF's probabilistic ocean wave guidance. It couples the WAM wave model with the atmospheric IFS, producing 51 ensemble members (50 perturbed + 1 control) every six hours. By sampling model and initial condition uncertainty, IFS Waef delivers a spread of plausible sea state scenarios—crucial for offshore operations, coastal engineering, and voyage optimisation.

This open data subset provides global wave fields on a 0.25° grid in GRIB2 format. In GribStream's current index, the 00/12 UTC cycles reach 360 h (15 days), while the 06/18 UTC cycles reach 144 h.

Detail

Parameters

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Click a parameter to reveal variants in a compact table with ready-to-copy JSON selectors.

cdww –Coefficient of drag with waves (dimensionless)
1 variant

Parameter ID 140233

ECMWF param DB

Wave-model drag coefficient describing the surface stress coupling between winds and waves.

  • Published with ECMWF wave-model output and useful for diagnosing air-sea momentum exchange.
Level Info Horizon Introduced Selector
sfc 0h-360h 2026-05-12
{"name":"cdww","level":"sfc","info":""}
h1012 –Significant wave height of all waves with periods from 10 to 12 seconds (m)
1 variant

Parameter ID 140114

ECMWF param DB

Significant wave height contributed by waves with periods from 10 to 12 seconds.

  • Period-band wave height fields help separate sea states by wave-period class.
Level Info Horizon Introduced Selector
sfc 0h-360h 2026-05-12
{"name":"h1012","level":"sfc","info":""}
h1214 –Significant wave height of all waves with periods from 12 to 14 seconds (m)
1 variant

Parameter ID 140115

ECMWF param DB

Significant wave height contributed by waves with periods from 12 to 14 seconds.

  • Period-band wave height fields help separate sea states by wave-period class.
Level Info Horizon Introduced Selector
sfc 0h-360h 2026-05-12
{"name":"h1214","level":"sfc","info":""}
h1417 –Significant wave height of all waves with periods from 14 to 17 seconds (m)
1 variant

Parameter ID 140116

ECMWF param DB

Significant wave height contributed by waves with periods from 14 to 17 seconds.

  • Period-band wave height fields help separate sea states by wave-period class.
Level Info Horizon Introduced Selector
sfc 0h-360h 2026-05-12
{"name":"h1417","level":"sfc","info":""}
h1721 –Significant wave height of all waves with periods from 17 to 21 seconds (m)
1 variant

Parameter ID 140117

ECMWF param DB

Significant wave height contributed by waves with periods from 17 to 21 seconds.

  • Period-band wave height fields help separate sea states by wave-period class.
Level Info Horizon Introduced Selector
sfc 0h-360h 2026-05-12
{"name":"h1721","level":"sfc","info":""}
h2125 –Significant wave height of all waves with periods from 21 to 25 seconds (m)
1 variant

Parameter ID 140118

ECMWF param DB

Significant wave height contributed by waves with periods from 21 to 25 seconds.

  • Period-band wave height fields help separate sea states by wave-period class.
Level Info Horizon Introduced Selector
sfc 0h-360h 2026-05-12
{"name":"h2125","level":"sfc","info":""}
h2530 –Significant wave height of all waves with periods from 25 to 30 seconds (m)
1 variant

Parameter ID 140119

ECMWF param DB

Significant wave height contributed by waves with periods from 25 to 30 seconds.

  • Period-band wave height fields help separate sea states by wave-period class.
Level Info Horizon Introduced Selector
sfc 0h-360h 2026-05-12
{"name":"h2530","level":"sfc","info":""}
mp2 –Mean zero-crossing wave period (s)
1 variant

Parameter ID 140221

ECMWF param DB

Mean time between sea-surface crossings of mean sea level.

  • Derived from the two-dimensional wave spectrum that combines waves of different heights, lengths, and directions.
  • Useful with wave height to estimate time under water for coastal structures.
Level Info Horizon Introduced Selector
sfc 0h-360h 2024-03-01
{"name":"mp2","level":"sfc","info":""}
mwd –Mean wave direction (Degree true)
1 variant

Parameter ID 140230

ECMWF param DB

Mean direction of ocean surface waves averaged over the wave spectrum.

  • Accounts for both wind-sea and swell components.
  • Direction is in degrees true (0 = from north, 90 = from east).
Level Info Horizon Introduced Selector
sfc 0h-360h 2024-03-01
{"name":"mwd","level":"sfc","info":""}
mwp –Mean wave period (s)
1 variant

Parameter ID 140232

ECMWF param DB

Average time between successive wave crests based on the wave spectrum.

  • Accounts for both wind-sea and swell components.
  • Useful for sea state assessments and marine engineering.
Level Info Horizon Introduced Selector
sfc 0h-360h 2024-03-01
{"name":"mwp","level":"sfc","info":""}
pp1d –Peak wave period (s)
1 variant

Parameter ID 140231

ECMWF param DB

Period of the most energetic ocean waves associated with the spectral peak.

  • Computed from the reciprocal of the frequency at the peak of the wave spectrum.
  • Includes contributions from both wind-sea and swell.
Level Info Horizon Introduced Selector
sfc 0h-360h 2024-03-01
{"name":"pp1d","level":"sfc","info":""}
swh –Significant height of combined wind waves and swell (m)
1 variant

Parameter ID 140229

ECMWF param DB

Average height of the highest one-third of wind + swell waves.

  • Defined as four times the square root of the spectral variance (integral over all frequencies and directions).
  • Used to assess sea state and structural loading offshore.
Level Info Horizon Introduced Selector
sfc 0h-360h 2024-03-01
{"name":"swh","level":"sfc","info":""}
wmb –Model bathymetry (m)
1 variant

Parameter ID 140219

ECMWF param DB

Bathymetry used by the ECMWF wave model.

  • This is a model-grid field used by the wave model, not an observed water-depth analysis.
Level Info Horizon Introduced Selector
sfc 0h-360h 2026-05-12
{"name":"wmb","level":"sfc","info":""}

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