MESMER v1.0.0: consolidating the modular Earth system model emulator into a sustainable research software package

Abstract. We present version v1.0.0 of MESMER – the Modular Earth System Model Emulator with spatially Resolved output. MESMER is a comprehensive software package for spatially resolved climate emulation. Version 1.0.0 revises the source code of several emulation approaches developed as part of earlier versions of MESMER and integrates them into a single python package that is readily available to the scientific community. We present the different MESMER components and the development strategy used to integrate them. MESMER v1.0.0 is numerically stable, faster than previous versions, employs a modern data structure, and better disentangles data handling and the statistical core. We demonstrate that MESMER v1.0.0 is now a sustainable research software according to requirements for modularity, code quality, documentation, and reproducibility. Available output variables are annual and monthly mean temperature as well as several climate extreme indicators. The calibration of MESMER can take from a few seconds up to half an hour, while large ensembles of climate realizations can now be produced (emulated) in just a few minutes. We facilitate the adoption of MESMER for the broad research community by providing pre-calibrated parameters, in a first step, for the emulation of annual mean temperature. MESMER v1.0.0 represents a crucial milestone in the coordination of on-going and upcoming developments of the MESMER Earth System Model emulator.