ROCKE-3D 2.0: an updated general circulation model for simulating the climates of rocky planets

Abstract. We present the second generation of ROCKE-3D (Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics), a generalized three-dimensional general circulation model (GCM) for use in Solar System and exoplanetary simulations of rocky planet climates. ROCKE-3D version 2.0 is a descendant of ModelE2.1, the flagship Earth system model of the NASA Goddard Institute for Space Studies (GISS) used in the most recent Intergovernmental Panel on Climate Change (IPCC) assessments. ROCKE-3D is a continuous effort to expand the capabilities of GISS ModelE to handle a broader range of planetary conditions, including different atmospheric planet sizes, gravities, pressures, and rotation rates; more diverse chemistry schemes and atmospheric compositions; diverse ocean and land distributions and topographies; and potential basic biosphere functions. In this release we present updated physics and many more supported configurations which can serve as starting points to simulate the atmospheres of rocky terrestrial planets of interest. Two different radiation schemes are supported, the GISS radiation, valid only for atmospheres similar to that of modern Earth, and SOCRATES, which is more generalized but more computationally expensive. While ROCKE-3D can simulate a very wide range of planetary and atmospheric configurations, we describe here a small subset of them, with the goal of demonstrating the structural capabilities, rather than the scientific breadth, of the model. Three different atmospheric composition options (preindustrial Earth, the aerosol-free and ozone-free atmosphere used in ROCKE-3D 1.0, and an anoxic atmosphere with no aerosols), three ocean configurations (prescribed, Q-flux, and dynamic), and two resolutions are described: the medium resolution (4×5° in latitude and longitude, previously used in ROCKE-3D 1.0) and the fine resolution, which has double the resolution in the atmosphere and 4 times the horizontal and 3 times the vertical resolution in the ocean. Finally, for the land surface hydrology, we have introduced generalized physics for arbitrary topography in the pooling and evaporation of water and river transport of water between grid cells, as well as for the vertical stratification of temperature in dynamic lakes. We quantify how the different component choices affect model results and discuss the strengths and limitations of using each component, together with how one can select which component to use. ROCKE-3D is publicly available, and tutorial sessions are available for the community, greatly facilitating its use by any interested group.

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