Summary

GloFAS v1 uses the Lisflood river routing model (van der Knijff et al., 2010) to propagate along the river channel the surface and sub-surface runoff outputs of the HTESSEL land surface model (Balsamo et al., 2009) of the ECMWF Integrated Forecast System to produce daily discharge simulations.

In GloFAS v1, Lisflood configuration uses expert-defined parameters which are uniform across the entire geographical domain, regardless of land surface characteristics.

GloFAS v1.0 Evaluation Results

Technical details

Release date2018-04-23
In test suite2018-03-23

GloFAS release

001
Archiving of data

ecfs

Reanalysis1990-1992, 2000-2007, 2010-2016
Horizontal resolution0.1 x 0.1°

GloFAS 30-day v1.0

Overview

GloFAS 30-day v1.0 meteorological forecasts (NWP) forcing is the ECMWF ENS medium- and extended-range forecasting system. Results are presented at daily resolution.

ECMWF ENS is the ensemble forecast of ECMWF and consists of 51 members at ~18 km resolution up to 15 days, increasing to ~36 km from days 16 to 30. ECMWF ENS runoff forecasts are resampled to 0.1° spatial resolution (~10 km) before being used as daily input to Lisflood to produce discharge up to day 15; from day 16 the latest available extended-range forecast is used as forcing to produce seamless discharge forecasts for 30 days. HRES is the high-resolution component of ECMWF Integrated Forecasting System and has a ~9 km horizontal resolution.

GloFAS 30-day v1.0 initial conditions (atmosphere and land surface states from which to start the ensemble discharge forecast) are based on day-1 of ECMWF HRES runoff forecasts for the 5 days prior to the forecast.

GloFAS 30-day v1.0 reference river discharge runs

GloFAS 30-days v1.0 reference river discharge runs are a collection of river discharge simulations as close as possible to GloFAS 30-day v1.0 operational system.

GloFAS 30-day v1.0 river discharge reanalysis is based on ERA-Interim/Land data, a surface-only version of ERA-Interim, ECMWF’s atmospheric reanalysis produced with a 2006 version of the IFS. ERA-Interim/Land data shares the same atmospheric forcing as ERA-Interim (~80 km grid resolution) although it benefits from a better description of land surface processes. GloFAS 30-day v1.0 river discharge reanalysis covers the 1980-2016 period.

GloFAS 30-days v1.0 river discharge forecasts reforecasts are produced from twice weekly, 20-year (1997-2016), 11-member ensemble ECMWF ENS reforecasts using GloFAS 30-day v1.0 operational settings. The initial conditions are taken from GloFAS v1.0 hydrological reanalysis. GloFAS 30-day v1.0 reforecasts have 20 years of daily discharge ensemble data (for 1997-2016), and can be used to assess GloFAS 30-day v1.0 skill.

GloFAS 30-day v1.0 river discharge thresholds are generated by fitting a Gumbel extreme value distribution to the annual maxima series extracted from GloFAS 30-day v1.0 discharge time series of GloFAS 30-day v1.0 hydrological reanalysis (1980-2016) using the method of L-moments; a filtering of dry day is applied prior to the distribution fitting. GloFAS 30-day v1.0 river discharge thresholds are used to generate flood awareness forecast maps.

GloFAS 30-day v1.0 products

GloFAS 30-day v1.0 products are generated by comparing GloFAS 30-day v1.0 river discharge forecasts with GloFAS 30-day v1.0 river discharge thresholds. They include exceedance probability maps and forecast hydrographs, and are available daily through the GloFAS map viewer.

GloFAS 30-day v1.0 available data

GloFAS 30-day v1.0 available data is summarised in the table below. It contains the period covered, the production frequency, the number of ensemble members and the ECMWF IFS versions used for each dataset. Note that GloFAS 30-day v1.0 datasets only include daily river discharge time series.

GloFAS 30-day v1.0PeriodFrequencyEnsemble membersECMWF IFS version
ReanalysisERAI-Land: Jan 1980 - June 2016
HRES: Jul 2016 - Apr 2018		Daily1ERAI-Land: 41r2
41r2: 8 Mar 2016 - 22 Nov 2016
43r1: 23 Nov 2016 -10 Jul 2017
43r3: 11 Jul 2017 - 4 Jun 2018
45r1: 5 Jun 2018 - real-time
ReforecastsJan 1997 - Dec 2016Twice
weekly		1143r1: 1 Jan 2017 - 10 July 2017
43r3: 11 Jul 2017 - 31 Dec 2017
Real-time forecasts23 Apr 2018 - 13 Nov 2018Daily5143r3: 11 Jul 2017 - 4 Jun 2018
45r1: 5 Jun 2018 - real-time

GloFAS-Seasonal v1.0

Overview

GloFAS Seasonal v1.0 is forced with forecasts from the ECMWF SEAS5 seasonal system. Results are presented as weekly averages, starting every Monday.

SEAS5 runoff ensemble has 51 members at ~36 km horizontal resolution, which are resampled to 0.1° spatial resolution (~10 km) before used as daily input to Lisflood. In GloFAS Seasonal v1.0, only the first 16 weeks (out of the available 7 months) of SEAS5 are processed.

GloFAS Seasonal v1.0 initial conditions (atmosphere and land surface states from which to start the ensemble discharge forecast) are based on the ERA5v0 ECMWF reanalysis (a monitoring analysis of the latest observations), using a configuration as close as GloFAS Seasonal v1.0 operational system. In practice, for the real-time forecasts, GloFAS Seasonal v1.0 initial conditions are taken as GloFAS 30-day v1.0 river discharge reanalysis generated in near-real time.

GloFAS Seasonal v1.0 reference river discharge runs

GloFAS Seasonal v1.0 reference river discharge runs are a collection of discharge simulations as close as possible to GloFAS Seasonal v1.0 operational system.

GloFAS Seasonal v1.0 river discharge reanalysis is a long deterministic hydrological simulation based on ERA5v0, the atmospheric reanalysis product of ECMWF available in 2018. ERA5v0 has a horizontal resolution of ~32 km (see Hersbach and Dee 2016 for further reading). GloFAS Seasonal v1.0 river discharge reanalysis covers three separate periods (1990-1992, 2000-2007, 2010-2016). 

GloFAS Seasonal v1.0  river discharge forecast reforecasts are forecast simulations performed for a set of past dates (1990-1992, 2000-2007, 2010-2016) using ECMWF Seasonal forecasting system SEAS5, based on a configuration as close as possible to GloFAS Seasonal v1.0 operational setting. They are initialised from GloFAS Seasonal v1.0 hydrological reanalysis. They are used to compute GloFAS Seasonal v1.0 river discharge thresholds and to analyse GloFAS Seasonal v1.0 river discharge forecast skill systematically over a long period.

GloFAS Seasonal v1.0 river discharge thresholds are river discharge magnitude corresponding to fixed percentile values, derived from the 18-year GloFAS Seasonal v1.0 forecasts reforecasts separately for each month of the year and each weekly lead-time. GloFAS Seasonal v1.0 river discharge thresholds are used to generate river flow anomaly forecast maps.

GloFAS Seasonal v1.0 products

GloFAS Seasonal v1.0 products are generated by comparing, for each lead-time to 16 weeks, the 51 scenarios of GloFAS Seasonal v1.0 weekly-averaged river discharge forecasts to the corresponding GloFAS Seasonal v1.0 river discharge thresholds. They include exceedance probability maps and weekly forecast hydrographs, and are available on the 10th of each month through the GloFAS map viewer.

GloFAS Seasonal v1.0 available data

GloFAS Seasonal v1.0 is not available to users.