nextGEMS simulations

nextGEMS is building prototypes for a new generation of earth system models to advance science, guide policy, and inform applications to support the sustainable management of our planet. Today’s Earth System Models use grids designed to capture the horizontal, but not the vertical, motion fields of atmospheric circulations. This shortcut, while computationally expedient, requires important processes to be neglected, or represented empirically. By using a fifty-fold finer horizontal grid (3 km compared to the 150 km) storm resolving models are able to explicitly represent the circulations that make the storms in the atmosphere, the eddies in the ocean, and cracks in the ice, a leap in realism that is only now becoming possible thanks to advances in super-computing.

nextGEMS drives the development of two European storm-resolving Earth-system Models, IFS and ICON. The models undergo three development cycles with successive improvement and optimization of the model configuration and workflow. Below we provide information on the model development cycles and their respective simulations at various horizontal resolutions and changing model configuration. We intend to provide information as soon as they become available. However, this is by no means a complete model description but shall rather provide a quick overview of available experiments. Also, please keep in mind that the models are under constant change during the development phase. We try to keep track for you here. The following links point to relevant background knowledge on the models:

Icosahedral Nonhydrostatic Weather and Climate Model (ICON)
The ECMWF Integrated Forecasting System (IFS)

IFS-H is a hydrostatic spectral transform model with a semi-Lagrangian semi-implicit solution procedure, discretised on a cubic octahedral grid (Wedi 2014, Malardel et al. 2016). Here, the single precision version of IFS (cycle 45r2) is used.


Model development overview

nextGEMS project timeline.

Cycle 1

The Cycle 1 simulations are based on the DYAMOND Winter simulations, but run for one year at about 5 km horizontal resolution and for 2 to 3 months at 2.5 km resolution. Within Cycle 1, first bugs were detected and fixed such that some further runs are available with improved configuration.

Please find here an overview of the processed variables of Cycle 1


Here's a first overview of the IFS simulations we have processed so far.


The original Cycle 1 simulation from ICON developed out of the latest DYAMOND-Winter run (dpp0029) and is called dpp0052. This simulation was analyzed during the nextGEMS Cycle 1 Hackathon in October 2021.

Continuous development and especially the transition from the old (Mistral) to the new (Levante) supercomputer lead to significant workflow improvements (new compiler, new scripting). The dpp0066 (5 km) and dpp0067 (2.5 km) runs are the latest Cycle 1 simulations run on Levante. They include improvements on the model physics such as a bug fix for the surface wind stress over the ocean. A publication describing these simulations will be submitted end on June 2022. Those runs also served as a basis for a student hackathon at UCM (Madrid) in April 2022.

Cycle 2

The nextGEMS Cycle 2 simulations build up on the Cycle 1 simulations for both models, IFS/FESOM and ICON. They include improvements in the configuration (new schemes and features) and a change in the output. The simulations will be analyzed during the Cycle 2 hackathon in Vienna end of June 2022.


What’s new in Cycle 2?
  • radiation scheme changed from psRad to RRTMGp

  • river discharge coupling

  • new ocean spin-up with nudging to observed SST

  • new ocean vertical coordinate (z*) with thin surface levels

  • bug fix of dry static energy over land

Up to date we provide a 2-year simulation at 5 km resolution called ngc2009 and a 10-year simulation at 10 km resolution called ngc2012.

Monthly quicklook images for both runs are available on the DKRZ SWIFT browser.

In addition, we provide two simulations with and without aerosol perturbations over 10 days at 5 km resolution called ngc2009_irad32 and ngc2009_irad33.

Jupyter notebooks for an initial analysis are collected on the GitLab of DKRZ.


What’s new in Cycle 2?
  • Based on IFS cycle 47r3.3

  • Signficantly reduced global water and energy imbalances

  • Several upgrades in the surface-atmosphere interaction:
    • Multi-layer snow scheme

    • Improved high-resolution land, sea, lake, and glacier masks

    • Revised surface orographic drag

  • In FESOM:
    • Refactored code allowing hybrid MPI/OpenMP support; significantly faster in the single-executable setup with IFS

    • Newly developed NG5-grid with about 7.5 million surface nodes; down to ~5km resolution

    • New NG5 stand-alone ocean spin-up forced by ERA5 (without nudging to observed SST compared to ICON)

    • Allows for linear kinematic features (sea ice cracks)

    • Eddy-resolving in large areas of the globe; Tropical Instability Waves also resolved

  • WAM wave model:
    • For Cycle 2, we provide for the first time output of the wave model

  • High-frequency model output (‘DDH’):
    • At 30 selected points over the globe

The IFS model in combination with the FESOM and NEMO ocean models was run in 3 different main experiments for Cycle 2:

8 months-long and highest-resolved simulation with atmosphere at 2.5 km (IFS) coupled to ~5 km ocean (FESOM); Deep convection parameterization OFF.

Main Cycle 2 simulation over 1 full year with atmosphere at 4 km (IFS) coupled to ~5 km ocean (FESOM); Deep convection parameterization OFF.

Baseline simulation with atmosphere at 9 km (IFS) coupled to 0.25 degree ocean (NEMO); Deep convection parameterization ON.

To get an idea what the data can provide, animations of selected variables from the IFS-FESOM2 simulations (with date string) are available at the AWI Nextcloud (last access: 27 June 2022).