ICON-Sapphire (ICON-LEM)

The ICON large eddy model (ICON-LEM) is used to study small-scale processes such as cloud, convection and turbulence, with a horizontal grid spacing of O (10m – 1km). At a grid spacing of a few tens of meters, convection can be resolved fully explicitly instead of having to rely on uncertain parameterizations. ICON-LEM uses the Sapphire physics package from ICON-A (see below), with its default one-dimensional turbulence scheme replaced by a three-dimensional scheme, as 3D effects cannot be neglected at such high resolutions.

ICON-LEM can be used to study processes in more idealized configurations with cyclic horizontal boundary conditions and flat surfaces. But ICON-LEM also offers the possibility to simulate real cases by using prescribing lateral boundary conditions and ICON nesting capabilities (see Figure). Given the excellent scaling abilities of ICON, even large-domain large-eddy simulations, on domains as large as Germany, can be conducted on a day basis.

The figure shows snapshots of cloud images from satellite (MODIS) and ICON-LEM (synthetic radiances) for four synoptically distinct situations in April and May 2013.
They reveal the ability of ICON-LEM in reproducing many of the fine-scale structures of the flow like a field of shallow cumuli over northern Germany on April 24 or a line of cumuli over elevated areas as on April 25 (see Heinze et al. (2017) and Dipankar et al. (2015)).


Dr Cathy Hohenegger
Atmosphere in the Earth System
Phone: +49 40 41173 302
Email: cathy.hohenegger@we dont want spammpimet.mpg.de