Copernicus Emergency Management Service releases GloFAS v4.0 hydrological reanalysis

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A new, substantially upgraded hydrological reanalysis dataset of the Global Flood Awareness System (GloFAS) from 1980 to July 2022 has been produced by the Joint Research Centre (JRC) of the European Commission in collaboration with ECMWF and released as part of the Copernicus Emergency Management Service (CEMS). It puts river discharge and flood events during that period at the fingertips of users.

The GloFAS v4.0 reanalysis includes daily maps of discharge over the globe at a resolution of 0.05 degrees (about 5 km). It is available in the Climate Data Store of the Copernicus Climate Change Service (C3S) run by ECMWF.

Generating such a high-resolution reanalysis has been made possible by ECMWF’s new high-performance computing facility in Bologna, Italy. This updated version is a new edition of the GloFAS v3.1 reanalysis, which was introduced in 2021. The new dataset uses ERA5 (ECMWF’s latest reanalysis of the atmosphere), satellite-derived datasets, and a large number of ground measurements to describe catchment physical properties and for model calibration, combined with the LISFLOOD hydrological model.

The reanalysis makes it possible to study flood events and droughts globally during a much longer time frame than the period during which GloFAS has been operational. It is launched as the EU holds an extreme weather and natural disasters thematic day at the UN’s 27th Conference of the Parties (COP27) on climate change.

New elements

The open-source LISFLOOD hydrological model determines what happens with water that comes down as rain. It decides to what extent the water evaporates, is absorbed by the soil and plants, or runs off into rivers.

For the reanalysis upgrade, ECMWF and the JRC, which manages CEMS, both worked on LISFLOOD. This included upgrades in hydrological routines and improvements in the management of large input datasets and computational performance.

ECMWF improved the representation of rivers, soil and vegetation in the model, and the JRC calibrated the model and performed a parameter regionalisation for ungauged catchments to ensure the best possible simulation of river flows for all catchments around the world.

The new GloFAS v4.0 hydrological reanalysis also has a finer resolution than before: it works on a 0.05 degree grid (about 5 km) when before it used a 0.1 degree grid (about 10 km).

Significant changes in computational performance, made possible by the parallelisation of routines in the hydrological model LISFLOOD, combined with ECMWF’s new Atos HPCF, have enabled the global simulation at the increased spatial resolution.

source:

Copernicus Emergency Management Service releases GloFAS v4.0 hydrological reanalysis | ECMWF