ICON-Sapphire: simulating the components of the Earth system and their interactions at kilometer and subkilometer scales

Abstract

Abstract. State-of-the-art Earth system models typically employ grid spacings of O(100 km), which is too coarse to explicitly resolve main drivers of the flow of energy and matter across the Earth system. In this paper, we present the new ICON-Sapphire model configuration, which targets a representation of the components of the Earth system and their interactions with a grid spacing of 10 km and finer. Through the use of selected simulation examples, we demonstrate that ICON-Sapphire can (i) be run coupled globally on seasonal timescales with a grid spacing of 5 km, on monthly timescales with a grid spacing of 2.5 km, and on daily timescales with a grid spacing of 1.25 km; (ii) resolve large eddies in the atmosphere using hectometer grid spacings on limited-area domains in atmosphere-only simulations; (iii) resolve submesoscale ocean eddies by using a global uniform grid of 1.25 km or a telescoping grid with the finest grid spacing at 530 m, the latter coupled to a uniform atmosphere; and (iv) simulate biogeochemistry in an ocean-only simulation integrated for 4 years at 10 km. Comparison of basic features of the climate system to observations reveals no obvious pitfalls, even though some observed aspects remain difficult to capture. The throughput of the coupled 5 km global simulation is 126 simulated days per day employing 21 % of the latest machine of the German Climate Computing Center. Extrapolating from these results, multi-decadal global simulations including interactive carbon are now possible, and short global simulations resolving large eddies in the atmosphere and submesoscale eddies in the ocean are within reach.

Confronting the Convective Gray Zone in the Global Configuration of the Met Office Unified Model

“…Over tropical land and over the extratropics the biases are much less pronounced. Similar tropical rainfall biases have also been described in other convection‐permitting global atmosphere models (Caldwell et al., 2021; Hohenegger et al., 2022).…”

Wind Power Input to Ocean Near‐Inertial Waves Diagnosed From a 5‐km Global Coupled Atmosphere‐Ocean General Circulation Model

“…Further information on the 5 km coupled ICON simulation can be found in Hohenegger and et al. (2023), Gutjahr et al. (2022) and Mauritsen et al.…”

“…A coarse-resolution variant of the ICON-ESM is described by Jungclaus et al (2021). Further information on the 5 km coupled ICON simulation can be found in Hohenegger and et al (2023), Gutjahr et al (2022) and Mauritsen et al (2022). A detailed analysis of a tropical cyclone simulated by the 5 km ICON model is carried out by Kumar et al (2021).…”

Impact of Diurnal Warm Layers on Atmospheric Convection

“…We run both simulations for 30 days starting 21 January 2020 and with the coupling and radiation time steps of 12 min, the atmosphere time step of 30 s, and the ocean time step of 80 s. Both simulations have identical initial conditions, whereby the generation of the initial ocean state is described in Hohenegger et al. (2023). We call the runs with 128 and 139 ocean levels S control and S +DWL respectively.…”

“…The vertical grid that we chose is sufficiently coarse to obtain a numerically stable global run and produces DWLs whose temperature field is indistinguishable in its depth, magnitude and overall vertical structure from a run with a 10 cm uniform grid (compare Figure A2 in Appendix A and Figure 1). We run both simulations for 30 days starting 21 January 2020 and with the coupling and radiation time steps of 12 min, the atmosphere time step of 30 s, and the ocean time step of 80 s. Both simulations have identical initial conditions, whereby the generation of the initial ocean state is described in Hohenegger et al (2023). We call the runs with 128 and 139 ocean levels S control and S +DWL respectively.…”