This page describes the model output data (either direct output or processed) available from EFAS and GloFAS. Please see Data Access to obtain the data and Working with CEMS-Flood Data for examples of how to open, extract subsets and visualise the data.

EFAS Available Data

Presented here is a brief overview of the EFAS data made available to the public and registered EFAS users. For a full overview of the EFAS hydrological model LISFLOOD, please go to the dedicated pages. You will find information on the latest release of EFAS here: Latest operational EFAS release

EFAS datasets

EFAS Historical

This dataset provides gridded modelled hydrological time series forced with meteorological observations. The data set is a consistent representation of the most important hydrological variables across EFAS. The temporal resolution is up to 30 years modelled time series of:

River discharge
Soil wetness index (root zone) (from EFASv5.1)
Snow water equivalent
Runoff water equivalent (surface plus subsurface)
Volumetric soil moisture for three soil layers (EFASv4 and previous)

It also provides static data on soil depth for the three soil layers. Volumetric oil moisture and river discharge data are accompanied by Auxiliary Data for interpretation.

This dataset was produced by forcing the LISFLOOD hydrological model with gridded observational data of precipitation and temperature at a 1x1 arcminute (for version 5.0 onwards) resolution across the EFAS domain. The most recent version uses a 6-hourly time step, whereas older versions uses a 24-hour time step. It is available from 1992-01-01 up until near-real time, with a delay of 6 days. The real-time data is only available to EFAS partners. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	River discharge and related historical data from the European Flood Awareness System
Data type	Gridded
Projection	Regular latitude-longitude grid for version 5.0, and ETRS89 Lambert Azimuthal Equal Area (ETRS-LAEA) for version 4.0 and older.
Horizontal coverage	Europe - The domain spans from northern Africa beyond the northern tip of Scandinavia. In the west it ranges far into the Atlantic Ocean and in the east as far as to the Caspian Sea.
Horizontal resolution	1x1 arcminute for version 5.0, 5x5km for older versions
Vertical resolution	Surface level for river discharge and snow depth water equivalent; Subsurface level for soil wetness index; Surface and subsurface for runoff water equivalent; 3 levels for volumetric soil moisture.
Temporal coverage	1 January 1992 to near real time (6 day delay) for version 5.0, various dates for previous versions. Volumetric soil moisture is provided until 2024-03-20.
Temporal resolution	6-hourly from version 4, 24-hourly for previous versions.
Update frequency	New data are added continuously with a 6-day delay with respect to the actual date for the latest version. Older versions will be discontinued when a new version is released.
File format	GRIB2 and NetCDF-4
Versions	For a full description of the versions we refer to EFAS versioning system.
CDS DOI	https://doi.org/10.24381/cds.e3458969

EFAS Real-time Forecasts

This dataset provides gridded modelled hydrological time series forced with medium-range meteorological forecasts from EFAS. The temporal resolution is sub-daily high-resolution and ensemble forecasts of:

River discharge
Soil wetness index (root zone) (from EFAS v5.1)
Snow water equivalent
Runoff water equivalent (surface plus subsurface)
Volumetric soil moisture for three soil layers (EFAS v4 and previous)

It also provides static data on soil depth for the three soil layers. Volumetric soil moisture and river discharge data are accompanied by Auxiliary Data for interpretation.

This data set was produced by forcing the LISFLOOD hydrological model at a 1x1 arcminute (for version 5.0 onwards) resolution with meteorological forecasts. The forecasts are initialised twice daily at 00 and 12 UTC with time steps of 6 or 24 hours and lead times between 5 and 15 days depending on the forcing numerical weather prediction model. The forcing EFAS Meteorological forecasts are high-resolution and ensemble forecasts from ECMWF with 51 ensemble members, high-resolution forecasts from the Deutsches Wetter Dienst (DWD) and the ensemble forecasts from the COSMO Local Ensemble Prediction System (COSMO-LEPS) with 20 ensemble members. The hydrological forecasts are available from 2018-10-10 up until present with a 30-day delay. The real-time data is only available to EFAS partners. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	River discharge and related forecasted data from the European Flood Awareness System
Data type	Gridded
Projection	Regular latitude-longitude grid for version 5.0, and ETRS89 Lambert Azimuthal Equal Area (ETRS-LAEA) for version 4.0 and older.
Horizontal coverage	Europe - The domain spans from northern Africa beyond the northern tip of Scandinavia. In the west it ranges far into the Atlantic Ocean and in the east as far as to the Caspian Sea.
Horizontal resolution	1x1 arcminute for version 5.0, 5x5km for older versions
Vertical resolution	Surface level for river discharge and snow depth water equivalent; Subsurface level for soil wetness index; Surface and subsurface for runoff water equivalent; 3 levels for soil moisture.
Temporal coverage	10 October 2018 to near real-time with a 30-day delay.
Temporal resolution	Forecasts are initialized daily at 00 and 12 UTC with a 6 or 24-hourly time step and lead times up to 15 days.
Ensemble members	ECMWF-ENS = 51 members; COSMO-LEPS = 20 members; ECMWF-HRES = deterministic; DWD = deterministic
Update frequency	The EFAS forecasts are published on CDS at regular intervals with a minimum of 1 month lag with respect to the actual date.
File format	GRIB2 and NetCDF-4
Versions	Operational forecasts use the latest version of the EFAS system, hence the version will depend on the forecast initiation date. The version used to produce each individual forecast is included in the metadata, and the date in which it is valid for can be seen in Citation on the right hand side. For a full description of the versions we refer to EFAS versioning system.
CDS DOI	https://doi.org/10.24381/cds.9f696a7a

EFAS Reforecasts

This dataset provides gridded modelled hydrological time series forced with medium- to sub-seasonal range meteorological reforecasts from EFAS. The temporal resolution is 20 years of sub-daily reforecasts initialised twice weekly (Mondays and Thursdays) of:

River discharge
Soil wetness index (root zone) (from EFASv5.1)
Snow water equivalent
Runoff water equivalent (surface plus subsurface)
Volumetric soil moisture for three soil layers (EFASv4 and previous)

It also provides static data on soil depth for the three soil layers. Volumetric soil moisture and river discharge data are accompanied by Auxiliary Data for interpretation.

This dataset was produced by forcing the LISFLOOD hydrological model at a 1x1 arcminute (for version 5.0 onwards) resolution with ensemble meteorological reforecasts from ECMWF. Reforecasts are forecasts run over past dates and are typically used to assess the skill of a forecast system or to develop tools for statistical error correction of the forecasts. The reforecasts are initialised twice weekly with lead times up to 46 days, at 6-hourly time steps for 20 years. For more specific information on the how the reforecast dataset is produced we refer to EFAS medium-range forecast skill. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	Reforecasts of river discharge and related data from the European Flood Awareness System
Data type	Gridded
Projection	Regular latitude-longitude grid for version 5.0, and ETRS89 Lambert Azimuthal Equal Area (ETRS-LAEA) for version 4.0 and older.
Horizontal coverage	Europe - The domain spans from northern Africa beyond the northern tip of Scandinavia. In the west it ranges far into the Atlantic Ocean and in the east as far as to the Caspian Sea.
Horizontal resolution	1x1 arcminute for version 5.0, 5x5km for older versions
Vertical resolution	Surface level for river discharge and snow depth water equivalent; Subsurface level for soil wetness index; Surface and subsurface for runoff water equivalent; 3 levels for soil moisture.
Temporal coverage	For the operational version, reforecasts are generated in near real time for each Monday and Thursday as reference dates. For each reference date, reforecasts are produced for the past 20 years from 2003 to 2022 (inclusive). The first available reforecast reference date is the 2023-03-27.
Temporal resolution	Reforecasts are initialized at 00 UTC on Mondays and Thursdays with a 6-hourly time step and 46-day lead time.
Ensemble members	11
Update frequency	EFAS reforecasts are published at regular intervals on CDS, typically with every major EFAS upgrade.
File format	GRIB2 and NetCDF-4
Conventions	WMO standards for GRIB2. The NetCDF-4 files inherit the WMO GRIB2 conventions.
Versions	For a full description of the versions we refer to EFAS versioning system.
CDS DOI	https://doi.org/10.24381/cds.c83f560f

EFAS Seasonal real-time forecasts

This dataset provides gridded modelled daily hydrological time series forced with seasonal meteorological forecasts from EFAS. The temporal resolution is daily forecasts initialised once a month consisting of:

River discharge
Soil wetness index (root zone) (from EFASv5.1)
Snow water equivalent
Runoff water equivalent (surface plus subsurface)
Volumetric soil moisture for three soil layers (EFAS v4 and previous)

It also provides static data on soil depth for the three soil layers. Volumetric soil moisture and river discharge data are accompanied by Auxiliary Data for interpretation.

This dataset was produced by forcing the LISFLOOD hydrological model at a 1x1 arcminute (for version 5.0 onwards) resolution with seasonal meteorological ensemble forecasts. The forecasts are initialised on the first of each month with a lead time of 215 days at 24-hour time steps. The meteorological data are seasonal forecasts (SEAS5) from ECMWF with 51 ensemble members. The forecasts are available from November 2020. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	Seasonal forecasts of river discharge and related data from the European Flood Awareness System
Data type	Gridded
Projection	Regular latitude-longitude grid for version 5.0, and ETRS89 Lambert Azimuthal Equal Area (ETRS-LAEA) for version 4.0 and older.
Horizontal coverage	Europe - The domain spans from northern Africa beyond the northern tip of Scandinavia. In the west it ranges far into the Atlantic Ocean and in the east as far as to the Caspian Sea.
Horizontal resolution	1x1 arcminute for version 5.0, 5x5km for older versions
Vertical resolution	Surface level for river discharge and snow depth water equivalent; Subsurface level for soil wetness index; Surface and subsurface for runoff water equivalent; 3 levels for soil moisture.
Temporal coverage	1 November 2020 to near real-time.
Temporal resolution	Forecasts are initialized the first of each month at 00 UTC with a 24-hour time step and lead time of 215 days.
Ensemble members	51
Update frequency	The EFAS forecasts are published on CDS every month.
File format	GRIB2 and NetCDF-4
Conventions	WMO standards for GRIB2. The NetCDF-4 files inherit the WMO GRIB2 conventions
Versions	Operational forecasts use the latest version of the EFAS system, hence the version will depend on the forecast initiation date. The version used to produce each individual forecast is included in the metadata, and the date in which it is valid for can be seen in Citation on the right hand side. For a full description of the versions we refer to the wiki pages in EFAS versioning system.
CDS DOI	https://doi.org/10.24381/cds.eb224b0e

EFAS Seasonal reforecasts

This dataset provides modelled daily hydrological time series forced with seasonal meteorological reforecasts from EFAS. The temporal resolution is daily forecasts initialised once a month over the reforecast period 1991-2020 of:

River discharge
Soil wetness index (root zone) (from EFASv5.1)
Snow water equivalent
Runoff water equivalent (surface plus subsurface)
Volumetric soil moisture for three soil layers (EFASv4 and previous)

It also provides static data on soil depth for the three soil layers. Volumetric soil moisture and river discharge data are accompanied by Auxiliary Data for interpretation.

This dataset was produced by forcing the LISFLOOD hydrological model at a 1x1 arcminute (for version 5.0 onwards) gridded resolution with seasonal meteorological ensemble reforecasts. Reforecasts are forecasts run over past dates and are typically used to assess the skill of a forecast system or to develop tools for statistical error correction of the forecasts. The reforecasts are initialised on the first of each month with a lead time of 215 days at 24-hour time steps. The forcing meteorological data are seasonal reforecasts from ECMWF, consisting of 25 ensemble members up until December 2016, and after that 51 members. Hydrometeorological reforecasts are available from 1991-01-01 up until 2020-10-01. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	Seasonal reforecasts of river discharge and related data from the European Flood Awareness System
Data type	Gridded
Projection	Regular latitude-longitude grid for version 5.0, and ETRS89 Lambert Azimuthal Equal Area (ETRS-LAEA) for version 4.0 and older.
Horizontal coverage	Europe - The domain spans from northern Africa beyond the northern tip of Scandinavia. In the west it ranges far into the Atlantic Ocean and in the east as far as to the Caspian Sea.
Horizontal resolution	1x1 arcminute for version 5.0, 5x5km for older versions
Vertical resolution	Surface level for river discharge and snow depth water equivalent; Subsurface level for soil wetness index; Surface and subsurface for runoff water equivalent; 3 levels for soil moisture.
Temporal coverage	1 January 1991 to near real-time (several months delay) for the operational version
Temporal resolution	Forecasts are initialized the first of each month at 00 UTC and run with a 24-hour time step with a lead time of 215 days.
Ensemble members	25 members up until December 2016, and after that 51 members
Update frequency	The reforecasts will be updated when there is a new version of the seasonal forecast or the EFAS system
File format	GRIB2 and NetCDF-4
Versions	Current version - EFAS v4.0 released 2020-10-14. For more information on versions we refer to EFAS versioning system.
CDS DOI	https://cds.climate.copernicus.eu/cdsapp#!/dataset/efas-seasonal-reforecast?tab=overview

EFAS variables

EFAS variables (called 'parameters' in ECMWF MARS) are the hydrological entities calculated by the modelling chain.

From EFAS v5.1, the following variables are made available:

River discharge,
Soil wetness index (root zone) (see Soil wetness index (root zone) for details),
Runoff water equivalent (surface plus subsurface),
Snow depth water equivalent.

For EFAS v5.0 and earlier, the variable 'volumetric soil moisture content' was available. This variable has been withdrawn since the release of EFAS v5.1 on 2024-03-20.

For EFAS v3.5 and earlier, all variables were only available for 24-hourly time steps. Since EFAS v4.0, all variables are only available for 6-hourly time steps (but can be aggregated to 24-hourly for all non-instantaneous variables).

EFAS Short Description	Unit	GRIB parameter ID	GRIB Short name	GRIB Name	Comment	GRIB description	CDS description
River discharge	m3/s	240023/ 240024	dis06/ dis24	Mean discharge in the last 6/ 24 hours	Average	Volume rate of water flow, including sediments, chemical and biological material, in the river channel averaged over a time step through a cross-section	Same as GRIB description
Snow depth water equivalent	kg/m2 (mm)	228141	sd	Snow depth water equivalent	Instantaneous at the end of the model time step	Snow depth water equivalent in kg m**-2 (mm) water equivalent	The value represents the mass of water per square meter if all the snow in the grid box would be melted. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued model time step
Soil wetness index (see Soil wetness index (root zone) for details)	Numeric	231026	swir	Soil wetness index (root zone)	Instantaneous at the end of the model time step	The volume of water over the total volume of voids in the soil, expressed as an index with values between 0 (residual soil moisture) and 1 (saturation), representing the lower and upper soil moisture limits of the root zone. The root zone is the maximum depth at which plants can extract water from the soil. Voids are empty spaces in the soil column that can be filled with water or air.	The volume of water over the total volume of voids in the soil, expressed as an index with values between 0 (residual soil moisture) and 1 (saturation), representing the lower and upper soil moisture limits of the root zone. The root zone is the maximum depth at which plants can extract water from the soil. Voids are empty spaces in the soil column that can be filled with water or air.
Runoff water equivalent	kg/m²	231002	rowe	Runoff water equivalent (surface plus subsurface)	Accumulation	Some water from rainfall, melting snow, or deep in the soil, stays stored in the soil. Otherwise, the water drains away, either over the surface (surface runoff), or under the ground (sub-surface runoff) and the sum of these two is simply called 'runoff'. This parameter is the total amount of water accumulated over a particular time period which depends on the data extracted.The units of runoff are depth in metres. This is the depth the water would have if it were spread evenly over the grid box. Care should be taken when comparing model parameters with observations, because observations are often local to a particular point rather than averaged over a grid square area. Observations are also often taken in different units, such as mm/day, rather than the accumulated metres produced here. Runoff is a measure of the availability of water in the soil, and can, for example, be used as an indicator of drought or flood.	The sum of the surface and sub-surface runoff, and represents all the water that would drain away from the grid box. This variable is the total amount of water accumulated from the beginning of the time step to the end of the time step.
Soil depth	m	260367	sod	Soil depth	Set of three values. Depth from the surface to the bottom of each layer	Soil depth, positive downward. It is meant to be used together with the type of level 'soil level' to encode the depth of the level at each grid point	Soil depth, positive downward for each of the three soil layers at each grid point. The value is relative from the top of the land surface to the bottom of each layer respectively
Volumetric soil moisture content (Withdrawn on 2024-03-20)	m3 /m3	260199	vsw	Volumetric soil moisture	Instantaneous at the end of the model time step Available for three soil layers	Volumetric soil moisture	Amount of water in a cubic meter of soil valid for the cell grid at the corresponding soil layer. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued model time step. For more documentation on the calculation of the volumetric soil moisture we refer to the documentation.

River Discharge

EFAS variable river discharge (dis) is stored as average over the time step of the model (6-hourly or 24-hourly), with time stamp (date and time of end of averaging period) explicit in the GRIB short name.

In EFAS, river discharge is calculated in each grid box of the hydrological model. However, not all grid boxes correspond to a river segment, and because of the relatively coarse resolution of the EFAS gridded domain, the modelled river network in EFAS might be associated with slightly different latitude-longitude than in the real world. It is hence essential that when extracting river discharge data, the user also checks the upstream area of the grid box of interest. The EFAS upstream area can be found in the Auxiliary Data pages.

Some short scripts to use as examples are provided in the Working with CEMS-Flood Data pages.

Snow depth water equivalent

Snow depth water equivalent represents the amount of water stored as ice and snow given as an instantaneous value at the end of each model time step. The time stamp (date and time of end of time step period) is explicit in the GRIB short name.

In EFAS, snow depth water equivalent in each grid box is calculated from three elevation-related bands to account for the difference in the melting rate with snow condition (see Auxiliary Data for more details). However, only the more directly usable composite snow map representing the total snow water equivalent for each grid box is made available.

Some short scripts to use as examples are provided in the Working with CEMS-Flood Data pages.

Soil wetness index (root zone)

Soil wetness index (root zone) represents the volume of water stored in the soil layers given as an instantaneous value at the end of each model time step.

EFAS soil wetness information is stored as the fraction of the total volume of voids in the root zone. The root zone is the maximum depth at which plants can extract water from the soil. Voids are empty spaces in the soil column that can be filled with water or air.

See Soil wetness index (root zone) for details.

Runoff water equivalent (surface and subsurface)

Runoff water equivalent (surface and subsurface) represents the sum of the surface and sub-surface runoff, and represents all the water that would drain away from the grid box. This variable is the total amount of water accumulated from the beginning of the time step to the end of the time step.

NOTE: If this variable were to be expressed as a value over the time step (e.g. 'runoff over the last 24 hours), it would become an average flux.

Volumetric soil moisture content - (Withdrawn on 2024-03-20)

Volumetric soil moisture content represents the amount of water stored in the soil layers given as an instantaneous value at the end of each model time step. The time stamp (date and time of end of time step period) is explicit in the GRIB short name.

EFAS volumetric soil moisture content in each grid box is calculated in three layers, top, intermediate and bottom, each associated with a given soil depth (depth from top to bottom of that layer). Information for each 3 layers is provided as separate data field, the soil depth (see Auxiliary Data for more details).

EFAS volumetric soil moisture information is stored as volumetric soil moisture content for each layer. The associated volume of water for that layer is volumetric soil moisture content multiplied by the layer thickness. The thickness of a specific layer is the difference between the depth of two consecutive layers.

The total volume soil moisture content is the sum of volume of water for each layer. Note that in EFAS-IS, only soil moisture of the first 2 layers is shown.

Some short scripts to use as examples are provided in the Working with CEMS-Flood Data pages.

EFAS Horizontal Resolution and Projection

Since EFAS v5.0, the LISFLOOD operational model is setup over Europe with the spatial resolution of 1 arcmin/ 0.0166667 degrees resolution (~1.4km). The geographical projection is the World Geodetic System 1984 (EPSG 4326). Its defining parameters can be found here.

Proj4 format: Proj4js.defs["EPSG:4326"] = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs"

For EFAS v4.0 and earlier, the LISFLOOD operational model was setup over Europe with the spatial resolution of 5 * 5 km with the geographical projection is the INSPIRE compliant ETRS89 Lambert Azimuthal Equal Area Coordinate Reference System (ETRS-LAEA). ETRS-LAEA is a single projected coordinate reference system for the pan-European area. It is based on the ETRS89 geodetic datum and the GRS80 ellipsoid, and is the recommended projection for pan-European statistical mapping at all scales or for other purposes where true area representation is required. Its defining parameters can be found here.

Proj4 format: Proj4js.defs["EPSG:3035"] = " +proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000 +ellps=GRS80 +units=m +no_defs "

Recommendation regarding EFAS outputs

We do not recommend to use EFAS for catchments below 50 km², most of our products/layers use 150 km² as a threshold (i.e. we do not evaluate the model skill/performance in catchments smaller than 150 km²).

GloFAS Available Data

Presented here is a brief overview of the GloFAS data made available to the public. For a full overview of the GloFAS system, please go to the dedicated wiki pages. You will find information on the latest releases here: Latest operational GloFAS release

GloFAS datasets

GloFAS Historical

This dataset contains global modelled daily data of river discharge from GloFAS. River discharge. This dataset is simulated by forcing the the LISFLOOD hydrological modelling chain with inputs from the ERA5 global reanalysis. Data availability for the operational historical simulation is from 1979-01-01 up to near real time. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	River discharge and related historical data from the Global Flood Awareness System
Data type	Gridded
Horizontal coverage	Global except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution	0.05° x 0.05° (~5 km)
Vertical resolution	Surface level for river discharge, Surface for snow depth water equivalent, Sub-surface for soil wetness index (root zone) Sub-surface for runoff water equivalent (surface plus subsurface)
Temporal coverage	1 January 1979 to near real-time (intermediate) and -2 months (consolidated)
Update frequency	A new river discharge reanalysis will be published with every major update of the GLOFAS system. The latest version will always be the version used in operations. For more information on the model versions, we refer to GloFAS versioning system.
Conventions	WMO standards for GRIB2
Versions	For more information on operational and historical versions we refer to above and the GloFAS versioning system.
CDS DOI	https://doi.org/10.24381/cds.ff1aef77

GloFAS real-time forecasts

This dataset contains global modelled daily data of river discharge forced with meteorological forecasts from GloFAS. This dataset is simulated by forcing the the LISFLOOD hydrological modelling chain with input from ECMWF ensemble forecast combined with the ECMWF extended-range ensemble forecast up to 30 days. Data availability for the GloFAS forecast is from 2019-11-05 up to near real time. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	River discharge and related forecasted data from the Global Flood Awareness System
Data type	Gridded
Projection	Regular latitude-longitude grid
Horizontal coverage	Global except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution	0.05° x 0.05° (~5 km)
Vertical resolution	Surface level for river discharge, Surface for snow depth water equivalent, Sub-surface for soil wetness index (root zone) Sub-surface for runoff water equivalent (surface plus subsurface)
Temporal coverage	5 November 2019 to near real time
Temporal resolution	Daily data
Ensemble members	51
Update frequency	Updated daily. For more information on the model versions, please refer to GloFAS versioning system.
File format	GRIB2 and NetCDF-4
Conventions	WMO standards for GRIB2. The NetCDF-4 files inherit the WMO GRIB2 conventions
Versions	For more information on versions we refer to GloFAS versioning system.
CDS DOI	https://doi.org/10.24381/cds.ff1aef77

GloFAS reforecasts

This dataset provides a gridded modelled time series of river discharge, forced with medium- to sub-seasonal range meteorological reforecasts from GloFAS. This dataset was produced by forcing the LISFLOOD hydrological modelling chain with input from the ECMWF-ENS 11-member ensemble reforecasts. Reforecasts are forecasts run over past dates, and those presented here are used for providing a suitably long time period against which the skill of the 30-day real-time operational forecast can be assessed. The reforecasts are initialised twice weekly with lead times up to 46 days, at 24-hour steps for 20 years in the recent history. For more specific information on the how the reforecast dataset is produced we refer to GloFAS forecast skill. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	Reforecasts of river discharge and related data from the Global Flood Awareness System
Data type	Gridded
Projection	Regular latitude-longitude grid
Horizontal coverage	Global except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution	0.05° x 0.05° (~5 km)
Vertical resolution	Surface level for river discharge, Surface for snow depth water equivalent, Sub-surface for soil wetness index (root zone) Sub-surface for runoff water equivalent (surface plus subsurface)
Temporal coverage	27 March 2003 to 26 February 2024
Temporal resolution	Reforecasts are initialised at 00 UTC twice weekly with a 24-hour time step and 46-day lead time
Ensemble members	11
Update frequency	GloFAS reforecasts are published at regular intervals on CDS, typically with every major GloFAS upgrade
File format	GRIB2
Conventions	WMO standards for GRIB2
Versions	For more information on versions we refer to GloFAS versioning system.
CDS DOI	https://doi.org/10.24381/cds.2d78664e

GloFAS Seasonal Forecasts

This dataset provides a gridded modelled time series of river discharge, forced with seasonal range meteorological forecasts from GloFAS. This dataset was produced by forcing the LISFLOOD hydrological model at a 0.1° (~11 km at the equator) resolution with downscaled runoff forecasts from the ECMWF 51-member ensemble seasonal forecasting system, SEAS5. The forecasts are initialised on the first of each month with a 24-hourly time step, and cover 123 or 215 days, depending on the date it was produced. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	Seasonal river discharge forecasts and Seasonal forecasts of river discharge and related data from the Global Flood Awareness System
Data type	Gridded
Projection	Regular latitude-longitude grid
Horizontal coverage	Global except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution	0.05° x 0.05° (~5 km)
Vertical resolution	Surface level for river discharge, Surface for snow depth water equivalent, Sub-surface for soil wetness index (root zone) Sub-surface for runoff water equivalent (surface plus subsurface)
Temporal coverage	01 December 2020 to near real time
Temporal resolution	Forecasts are initialised the first of each month with a 24-hourly time step, and cover 123 days until May 2021 and 215 days from June 2021
Ensemble members	51
Update frequency	Monthly, made available on the 10th of each month
File format	GRIB2
Conventions	WMO standards for GRIB2
Versions	For more information on versions we refer to GloFAS versioning system.
CDS DOI	https://doi.org/10.24381/cds.00b6c4fb

GloFAS Seasonal reforecasts

This dataset provides a gridded modelled time series of river discharge forced with seasonal range meteorological reforecasts from GloFAS. This dataset was produced by forcing the LISFLOOD hydrological modelling chain with input from the ECMWF ensemble seasonal forecasting system, SEAS5. For the period of 1981 to 2016 the number of ensemble members is 25, whilst reforecasts produced for 2017 onwards use a 51-member ensemble. Reforecasts are forecasts run over past dates, with those presented here used for producing the seasonal river discharge thresholds. In addition, they provide a suitably long time period against which the skill of the seasonal forecast can be assessed. The reforecasts are initialised monthly and run with 24-hourly time step for 123 days or 215 days, depending on the date it was produced. For more specific information on the how the seasonal reforecast dataset is produced we refer to the documentation. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
Dataset	Seasonal reforecasts of river discharge and related data from the Global Flood Awareness System
Data type	Gridded
Projection	Regular latitude-longitude grid
Horizontal coverage	Global except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution	0.05° x 0.05° (~5 km)
Vertical resolution	Surface level for river discharge, Surface for snow depth water equivalent, Sub-surface for soil wetness index (root zone) Sub-surface for runoff water equivalent (surface plus subsurface)
Temporal coverage	01 January 1981 to near real time (several months delay)
Temporal resolution	Reforecasts are initialised on the first of each month with a 24-hourly time run for 123 days for version 2.2 and earlier, and 215 days for version 3.1 and later.
Ensemble members	For the period of 1981 to 2016 the number of ensemble members is 25, whilst reforecasts produced for 2017 onwards use a 51-member ensemble
Update frequency	GloFAS reforecasts are published at regular intervals on CDS, typically with every major GloFAS upgrade
File format	GRIB2
Conventions	WMO standards for GRIB2
Versions	For more information on versions we refer to GloFAS versioning system.
CDS DOI	https://doi.org/10.24381/cds.0aa9b9dd

GloFAS variables

GloFAS variables (called 'parameters' in ECMWF MARS) are the hydrological entities calculated by the modelling chain.

From GloFAS v4.1, the following variables are made available:

River discharge in the last 24 hours,
Soil wetness index (root zone) (see Soil wetness index (root zone) for details),
Runoff water equivalent (surface plus subsurface),
Snow depth water equivalent.

For previous GloFAS versions, only the variable 'River discharge in the last 24 hours' was available.

A short description of variables is given below in table below, along with associated metadata information.

GloFAS Short Description	Unit	GRIB parameter ID	GRIB Short name	GRIB Name	Comment	GRIB description	CDS description
River discharge in the last 24 hours	m3/s	240024	dis24	Mean discharge in the last 24 hours	Average	Volume rate of water flow, including sediments, chemical and biological material, in the river channel averaged over a time step through a cross-section.	Same as GRIB description
Soil wetness index (see Soil wetness index (root zone) for details)	Numeric	231026	swir	Soil wetness index (root zone)	Instantaneous at the end of the model time step	The volume of water over the total volume of voids in the soil, expressed as an index with values between 0 (residual soil moisture) and 1 (saturation), representing the lower and upper soil moisture limits of the root zone. The root zone is the maximum depth at which plants can extract water from the soil. Voids are empty spaces in the soil column that can be filled with water or air.	The volume of water over the total volume of voids in the soil, expressed as an index with values between 0 (residual soil moisture) and 1 (saturation), representing the lower and upper soil moisture limits of the root zone. The root zone is the maximum depth at which plants can extract water from the soil. Voids are empty spaces in the soil column that can be filled with water or air.
Runoff water equivalent	kg/m²	231002	rowe	Runoff water equivalent (surface plus subsurface)	Accumulation	Some water from rainfall, melting snow, or deep in the soil, stays stored in the soil. Otherwise, the water drains away, either over the surface (surface runoff), or under the ground (sub-surface runoff) and the sum of these two is simply called 'runoff'. This parameter is the total amount of water accumulated over a particular time period which depends on the data extracted.The units of runoff are depth in metres. This is the depth the water would have if it were spread evenly over the grid box. Care should be taken when comparing model parameters with observations, because observations are often local to a particular point rather than averaged over a grid square area. Observations are also often taken in different units, such as mm/day, rather than the accumulated metres produced here. Runoff is a measure of the availability of water in the soil, and can, for example, be used as an indicator of drought or flood.	The sum of the surface and sub-surface runoff, and represents all the water that would drain away from the grid box. This variable is the total amount of water accumulated from the beginning of the time step to the end of the time step.
Snow depth water equivalent	kg/m2	228141	sd	Snow depth water equivalent	Instantaneous at the end of the model time step	Snow depth water equivalent in kg m**-2 (mm) water equivalent	The mass of water per square meter if all the snow in the grid box would be melted. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued model time step

River discharge

GloFAS variable river discharge (dis) is stored as average over the time step of the model (24-hourly), with time stamp (date and time of end of averaging period) explicit in the GRIB short name.

In GloFAS, river discharge is calculated in each grid box of the hydrological model. However, not all grid boxes correspond to a river segment, and because of the relatively coarse resolution of the GloFAS gridded domain, the modelled river network in GloFAS might be associated with slightly different latitude-longitude than in the real world. It is hence essential that when extracting river discharge data, the user also checks the upstream area of the grid box of interest. The GloFAS upstream area can be found in the Auxiliary Data pages.

Some short scripts to use as examples are provided in the Working with CEMS-Flood Data pages.

Snow depth water equivalent

Snow depth water equivalent represents the amount of water stored as ice and snow given as an instantaneous value at the end of each model time step.

In GloFAS, snow depth water equivalent in each grid box is calculated from three elevation-related bands to account for the difference in the melting rate with snow condition (see Auxiliary Data for more details). However, only the more directly usable composite snow map representing the total snow water equivalent for each grid box is made available.

Some short scripts to use as examples are provided in the Working with CEMS-Flood Data pages.

Soil wetness index (root zone)

Soil wetness index (root zone) represents the volume of water stored in the soil layers given as an instantaneous value at the end of each model time step.

GloFAS soil wetness information is stored as the fraction of the total volume of voids in the root zone. The root zone is the maximum depth at which plants can extract water from the soil. Voids are empty spaces in the soil column that can be filled with water or air.

See Soil wetness index (root zone) for details.

Runoff water equivalent (surface and subsurface)

Runoff water equivalent (surface and subsurface) represents the sum of the surface and sub-surface runoff, and represents all the water that would drain away from the grid box. This variable is the total amount of water accumulated from the beginning of the time step to the end of the time step.

GloFAS

NOTE: If this variable were to be expressed as a value over the time step (e.g. 'runoff over the last 24 hours), it would become an average flux.

Recommendation regarding GloFAS outputs

GloFAS is primarily designed for larger river catchments (over 10,000 km²), where the forecast skill is expected to be considerably higher. For small catchments, especially below 500 km², the uncertainties get much larger due to the horizontal resolution constraints (~5 km in the river network and ~9 km in the meteorological forcing such as precipitation). This is reflected in our products/layers which do consider a minimum catchment size of 250 km² or 500 km², depending on the product.

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Model Output

EFAS Available Data

EFAS datasets

EFAS Historical

EFAS Real-time Forecasts

EFAS Reforecasts

EFAS Seasonal real-time forecasts

EFAS Seasonal reforecasts

EFAS variables

EFAS Horizontal Resolution and Projection

Recommendation regarding EFAS outputs

GloFAS Available Data

GloFAS datasets

GloFAS Historical

GloFAS real-time forecasts

GloFAS reforecasts

GloFAS Seasonal Forecasts

GloFAS Seasonal reforecasts

GloFAS variables

Recommendation regarding GloFAS outputs