This page describes the model output data 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 moisture for three soil layers
  • Snow water equivalent

It also provides static data on soil depth for the three soil layers. Soil 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 5x5 km 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 1991-01-01 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 typeGridded
ProjectionThe geographical projection is the INSPIRE compliant ETRS89 Lambert Azimuthal Equal Area Coordinate Reference System (ETRS-LAEA).
Horizontal coverageEurope - 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 resolution5x5km
Vertical resolution3 levels for soil moisture; surface level for river discharge and snow depth water equivalent.
Temporal coverage1 January 1991 to near real time (6 day delay) for the most recent version.
Temporal resolution6-hourly from version 4, 24-hourly for previous versions.
Update frequencyNew data are added continuously with a minimum of 1 month lag with respect to the actual date for the latest version. Older versions will be discontinued when a new version is released.
File formatGRIB2 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 moisture for three soil layers
  • Snow water equivalent

It also provides static data on soil depth for the three soil layers. 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 5x5km 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
DatasetRiver discharge and related forecasted data from the European Flood Awareness System
Data typeGridded 
ProjectionThe geographical projection is the INSPIRE compliant ETRS89 Lambert Azimuthal Equal Area Coordinate Reference System (ETRS-LAEA).
Horizontal coverageEurope - 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 resolution5x5km
Vertical resolution3 levels for soil moisture; surface level for river discharge and snow depth water equivalent.
Temporal coverage10 October 2018 to near real-time with a 30-day delay.
Temporal resolutionForecasts are initialized daily at 00 and 12 UTC with a 6 or 24-hourly time step and lead times up to 15 days.
Ensemble membersECMWF-ENS = 51 members; COSMO-LEPS = 20 members; ECMWF-HRES = deterministic; DWD = deterministic 
Update frequencyThe EFAS forecasts are published on CDS at regular intervals with a minimum of 1 month lag with respect to the actual date.
File formatGRIB2 and NetCDF-4
VersionsOperational 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 DOIhttps://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 moisture for three soil layers
  • Snow water equivalent

It also provides static data on soil depth for the three soil layers. 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 5x5km 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
DatasetReforecasts of river discharge and related data from the European Flood Awareness System
Data typeGridded
ProjectionThe geographical projection is the INSPIRE compliant ETRS89 Lambert Azimuthal Equal Area Coordinate Reference System (ETRS-LAEA).
Horizontal coverageEurope - 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 resolution5x5km
Vertical resolution3 levels for soil moisture; surface level for river discharge and snow depth water equivalent.
Temporal coverage3 January 1999 to 30 December 2018.
Temporal resolutionReforecasts are initialized at 00 UTC on Mondays and Thursdays with a 6-hourly time step and 46-day lead time.
Ensemble members11
Update frequencyEFAS reforecasts are published at regular intervals on CDS, typically with every major EFAS upgrade.
File formatGRIB2 and NetCDF-4
ConventionsWMO standards for GRIB2. The NetCDF-4 files inherit the WMO GRIB2 conventions.
VersionsFor a full description of the versions we refer to EFAS versioning system.
CDS DOIhttps://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 moisture for three soil layers
  • Snow water equivalent

It also provides static data on soil depth for the three soil layers. 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 5x5km 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
DatasetSeasonal forecasts of river discharge and related data from the European Flood Awareness System
Data typeGridded
ProjectionThe geographical projection is the INSPIRE compliant ETRS89 Lambert Azimuthal Equal Area Coordinate Reference System (ETRS-LAEA).
Horizontal coverageEurope - 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 resolution5x5km
Vertical resolution3 levels for soil moisture; surface level for river discharge, snow depth water equivalent.
Temporal coverage1 November 2020 to near real-time.
Temporal resolutionForecasts are initialized the first of each month at 00 UTC with a 24-hour time step and lead time of 215 days.
Ensemble members51
Update frequencyThe EFAS forecasts are published on CDS every month.
File formatGRIB2 and NetCDF-4
ConventionsWMO standards for GRIB2. The NetCDF-4 files inherit the WMO GRIB2 conventions
VersionsOperational 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 DOIhttps://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 moisture for three soil layers
  • Snow water equivalent

It also provides static data on soil depth for the three soil layers. 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 5x5km 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
DatasetSeasonal reforecasts of river discharge and related data from the European Flood Awareness System
Data typeGridded
ProjectionThe geographical projection is the INSPIRE compliant ETRS89 Lambert Azimuthal Equal Area Coordinate Reference System (ETRS-LAEA).
Horizontal coverageEurope - 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 resolution5x5km
Vertical resolution3 levels for soil moisture; surface level for river discharge, snow depth water equivalent.
Temporal coverage1 January 1991 to 1 October 2020.
Temporal resolutionForecasts 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 members25 members up until December 2016, and after that 51 members
Update frequencyThe reforecasts will be updated when there is a new version of the seasonal forecast or the EFAS system
File formatGRIB2 and NetCDF-4
VersionsCurrent version - EFAS v4.0 released 2020-10-14. For more information on versions we refer to EFAS versioning system.
CDS DOIhttps://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.

Three types of EFAS variables are available: river discharge, snow depth water equivalent and volumetric soil moisture content. A short description is given below in the below table along with associated metadata information .

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 equivalentThe 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
Volumetric soil moisture content

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.
Soil depthm260367sod

Soil depth

Set of three values. Depth from the surface to the bottom of each layerSoil 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 pointSoil 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


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. 

Volumetric soil moisture content

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 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 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
DatasetRiver discharge and related historical data from the Global Flood Awareness System
Data typeGridded
Horizontal coverageGlobal except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution0.05° 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 coverage1 January 1979 to near real-time (intermediate) and -2 months (consolidated)
Update frequencyA 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.
ConventionsWMO standards for GRIB2
VersionsFor more information on operational and historical versions we refer to above and the GloFAS versioning system.
CDS DOIhttps://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
DatasetRiver discharge and related forecasted data from the Global Flood Awareness System
Data typeGridded
ProjectionRegular latitude-longitude grid
Horizontal coverageGlobal except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution0.05° 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 coverage5 November 2019 to near real time
Temporal resolutionDaily data
Ensemble members51
Update frequencyUpdated daily. For more information on the model versions, please refer to GloFAS versioning system.
File formatGRIB2 and NetCDF-4
ConventionsWMO standards for GRIB2. The NetCDF-4 files inherit the WMO GRIB2 conventions
VersionsFor more information on versions we refer to GloFAS versioning system.
CDS DOIhttps://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
DatasetReforecasts of river discharge and related data from the Global Flood Awareness System
Data typeGridded
ProjectionRegular latitude-longitude grid
Horizontal coverageGlobal except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution0.05° 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 coverage27 March 2003 to 26 February 2024
Temporal resolutionReforecasts are initialised at 00 UTC twice weekly with a 24-hour time step and 46-day lead time
Ensemble members11
Update frequencyGloFAS reforecasts are published at regular intervals on CDS, typically with every major GloFAS upgrade
File formatGRIB2
ConventionsWMO standards for GRIB2
VersionsFor more information on versions we refer to GloFAS versioning system.
CDS DOIhttps://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 data it was produced. Data can be accessed is several ways, the most common is through the CDS (see Data Access).

DATA DESCRIPTION
DatasetSeasonal river discharge forecasts and Seasonal forecasts of river discharge and related data from the Global Flood Awareness System
Data typeGridded
ProjectionRegular latitude-longitude grid
Horizontal coverageGlobal except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution0.05° 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 coverage01 December 2020 to near real time
Temporal resolutionForecasts 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 members51
Update frequencyMonthly, made available on the 10th of each month
File formatGRIB2
ConventionsWMO standards for GRIB2
Versions For more information on versions we refer to GloFAS versioning system.
CDS DOIhttps://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
DatasetSeasonal reforecasts of river discharge and related data from the Global Flood Awareness System
Data typeGridded
ProjectionRegular latitude-longitude grid
Horizontal coverageGlobal except for Antarctica (90N-60S, 180W-180E)
Horizontal resolution0.05° 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 coverage01 January 1981 to near real time (several months delay)
Temporal resolutionReforecasts 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 membersFor 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 frequencyGloFAS reforecasts are published at regular intervals on CDS, typically with every major GloFAS upgrade
File formatGRIB2
ConventionsWMO standards for GRIB2
VersionsFor more information on versions we refer to GloFAS versioning system.
CDS DOIhttps://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),
  • 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 

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 equivalentThe 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.

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.