nextGEMS 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.

As of Nov 2022, we have two 30-year simulations at 10km resolution called ngc2013 and rthk001. They both use TTE scheme for atmospheric turbulence (instead of Smagorinsky). The two differ only by thickness of the surface ocean layer.

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).