The ECHAM model is run at a spectral resolution of T127L95, where T127 denotes a spectral truncation at total wavenumber 127, which corresponds to about 100 km horizontal resolution in the tropics and higher horizontal (zonal) resolution towards the poles - for example about 25 km in 75° latitude. L95 stands for 95 unevenly spaced model levels with high vertical resolution close to the surface (60 to 300 m in the atmospheric boundary layer) and reaching up to 0.01 hPa corresponding to 80 km (i.e. high-top model version).
In our AWI-CM-1-1-MR CMIP6 contribution (Semmler et al. 2018), the FESOM model is run on a medium-resolution ”MR” mesh that follows the mesh design strategy proposed by Sein et al. (2016, 2017) (Fig. 1): The main approach is to locally increase the resolution over areas of high sea surface height (SSH) variability as obtained from satellite data. The horizontal resolution of the mesh varies from 8 km over energetically active areas such as the North Atlantic Current region to 80 km over areas with low SSH variability. The number of surface grid points of the MR mesh is close to the number of grid points in conventional regular model grids of ¼° resolution. The performance of the “MR-type” meshes in a climate configuration with AWI-CM in comparison to several other FESOM meshes is evaluated in de la Vara et al. (2020), Rackow et al. (2019), Sein et al. (2018).