EC-Earth 3 is based on ECMWF's atmospheric circulation model IFS, cycle 36r4, thus being in phase with the development of the seasonal prediction system at the European Centre. The ocean component comprises the latest version of the NEMO ocean model and for sea-ice modelling, the most recent Louvain-la-Neuve Sea Ice Model (LIM3) is utilised. Together, the component upgrades take EC-Earth a major step forward towards state-of-the-art in the earth system modelling community.
In an effort to make a complex model such as EC-Earth more suitable for new users and a growing community, a number of technical aspects have been reconsidered. EC-Earth 3 comes with a greatly simplified configuration procedure, including a graphical user interface, which allows an easy to use and interactive way of configuration. Moreover, portability of EC-Earth 3 has been addressed and is substantially improved over previous releases.
Acknowledging the fact that scientific software development is a complex matter, the development process itself has been reviewed and adapted to follow established best practices for software projects as far as possible. As a result, all development activities are now directed to the EC-Earth 3 Development Portal, a web based service that covers version control, issue tracking, documentation, and other means of communication between users and developers.
First results obtained from EC-EARTH 3 look promising. Most notable is the reduction of the cold bias and more realistic amounts of precipitation over the Amazon and Congo basin compared to the previous version (2.3). Another improvement is the better representation of stratocumulus clouds in the subtropical upwelling regions. These regions are characterized by relatively thin yet persistent stratocumulus clouds that have a strong impact on the radiative budget. Compared to observations from CERES-EBAF the mean bias in the SW cloud forcing does improve from version 2.3 to version 3, in particular the magnitudes of positive and negative anomalies are reduced (Figs. 1 and 2).
Even before the official release, EC-Earth 3 has been designated as one of the climate models to be utilised in a number of European projects, including IS-ENES2, EMBRACE, SPECS, and EUPORIAS.