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The following is a description of the latest operational release of GloFASGloFAS v4.1, available as fully operational GloFAS from 28 February 2024.

For  v3.5. For an overview of other GloFAS releases, please see : GloFAS versioning system.

Summary

GloFAS v3.5 integrates changes in its meteorological forcing used for the forecasts, with the use of the new version of the ECMWF-ENS ensemble forecasting system, introduced by IFS cycle 48r1. This change in the forcing data has the following impacts on GloFAS:

• Hydrological monitoring:
  • No change in the ECMWF-C3S ERA5- and ERA5-T-forced hydrological reanalysis simulations.
  • In the forecast initialisation (in the so-called fill-up, where ERA5-T is not yet available), the meteorological forcing resolution of ECMWF-ENS-CNTL has increased from 18 km to 9 km (similarly to the real time forecasts for days 1-15).
• Real time forecasts:
  • The spatial resolution of the forcing increases from 18 km to 9 km in the first 15 days of the 30-day forecast horizon, while the resolution of the extended-range forcing (days 16 to 30) remain unchanged at 36 km.
  • The extended-range ECMWF-ENS is produced every day in 48r1. Thus, the meteorological forcing for days 16-30 in GloFAS (which is blended after the first 15 days of higher resolution ENS) will always come from 1-day old forecast runs. Previously, it was coming from 1-4-day old forecast runs, depending on the day of the week, as the extended-range ENS was produced only on Mondays and Thursdays before 48r1.
• Reforecasts:
  • GloFAS v3.5 will not have a new 48r1-specific hydrological reforecast data set.
• Seasonal forecasts and seasonal reforecasts:
  • There is no impact on the seasonal hydrological modelling system.

More details on the 48r1 meteorological modelling changes can be found on the Implementation of IFS Cycle 48r1 page.

In addition, the v3.5 update also includes two additional reporting points in Bangladesh and Nigeria.

v4.1 introduces several minor changes to the system, including:

• Increased offering of forecast variables made available through the Climate Data Store. See Model Output page for details. The data will also be made available for the reanalysis: 
  • Runoff Water Equivalent (surface plus subsurface),
  • Snow Depth Water Equivalent,
  • and Soil Wetness Index (root-zone).
• Improved reporting point layer, with additional metadata available for 'dynamic reporting points'. 
• Improved information on the GloFAS map viewer (updated legends and layer titles). 
• GloFAS Flood thresholds available for various return periods, see Auxiliary Data pages for GloFAS v4.0 flood threshold files.

This upgrade of GloFAS has no impacts on the GloFAS modelling results.

Technical details