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GloFAS 30-day v1.0

GloFAS 30-day v1.0 was launched operationally on the 23rd April 2018, its last forecast issued the 13th November 2018

GloFAS 30-day v1.0 technical settings

GloFAS 30-day v1.0 uses the Lisflood river routing model (van der Knijff et al., 2010) to propagate along the river channel the surface and sub-surface runoff forecasts of the HTESSEL land surface model (Balsamo et al., 2009) of the ECMWF ENS medium- and extended-range forecasting system to produce daily discharge forecasts. In GloFAS 30-day v1.0, Lisflood configuration uses expert-defined parameters which are uniform across the entire geographical domain, regardless of land surface characteristics.

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.

The GloFAS system
Schematic of GloFAS 30-day v1.0.

GloFAS 30-day v1.0 reference discharge runs

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

GloFAS 30-day v1.0 hydrological 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 hydrological reanalysis covers the 1980-2016 period.

GloFAS 30-days v1.0 forecasts reruns 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 forecast reruns have 20 years of daily discharge ensemble data, and can be used to assess GloFAS 30-day v1.0 skill.

GloFAS 30-day v1.0 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. GloFAS 30-day v1.0 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 forecasts with GloFAS 30-day v1.0 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 discharge time series.

GloFAS 30-day v1.0 Period Frequency Ensemble members ECMWF IFS version
Reanalysis ERAI-Land: Jan 1980 - June 2016
HRES: Jul 2016 - Apr 2018
Daily 1 ERAI-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
Forecast reruns Jan 1997 - Dec 2016 Twice
11 43r1: 1 Jan 2017 - 10 July 2017
43r3: 11 Jul 2017 - 31 Dec 2017
Real-time forecasts 23 Apr 2018 - 13 Nov 2018 Daily 51 43r3: 11 Jul 2017 - 4 Jun 2018
45r1: 5 Jun 2018 - real-time

GloFAS 30-day v1.0 skill

A comparison of skill between GloFAS 30-day v1.0 and GloFAS 30-day v2.0 is in progress and results will be published once complete.