The EC-Earth3 Earth system model for the Coupled Model Intercomparison Project 6

The Earth system model EC-Earth3 for contributions to CMIP6 is documented here, with its flexible coupling framework, major model configurations, a methodology for ensuring the simulations are comparable across different high-performance computing (HPC) systems, and with the physical performance of base configurations over the historical period. The variety of possible configurations and sub-models reflects the broad interests in the EC-Earth community. EC-Earth3 key performance metrics demonstrate physical behavior and biases well within the frame known from recent CMIP models. With improved physical and dynamic features, new Earth system model (ESM) components, community tools, and largely improved physical performance compared to the CMIP5 version, EC-Earth3 represents a clear step forward for the only European community ESM. We demonstrate here that EC-Earth3 is suited for a range of tasks in CMIP6 and beyond.Peer reviewe

Surface mass balance of the Greenland ice sheet in the regional climate model HIRHAM5: Present state and future prospects

Surface mass balance (SMB) is the builder of the Greenland ice sheet and the driver of ice dynamics. Quantifying the past, present and future state of SMB is important to understand the drivers and climatic processes that control SMB, and to both initialize and run ice sheet models which will help clarify sea level rise, and how likely changes in ice sheet extent feedback within the climate system. Regional climate models (RCMs) and climate reanalysis are used to quantify SMB estimates. Although different models have different spatial and temporal biases and may include different processes giving significant uncertainty in both SMB and the ice sheet dynamic response to it, all RCMs show a recent declining trend in SMB from the Greenland ice sheet, driven primarily by enhanced melt rates. Here, we present new simulations of the Greenland ice sheet SMB at 5 km resolution from the RCM HIRHAM5. The RCM is driven by the ERA-Interim reanalysis and the global climate model (GCM) EC-Earth v2.3 to make future projections for climate scenarios RCP8.5 and RCP4.5. Future estimates of SMB are affected by biases in driving global climate models, and feedbacks between the ice sheet surface and the global and regional climate system are neglected, likely resulting in significant underestimates of melt and precipitation over the ice sheet. These challenges will need to be met to better estimate the role climate change will have in modulating the surface mass balance of the Greenland ice sheet

Determination of rate constants for the uptake process involving SO2 and an aerosol particle. A quantum mechanics/molecular mechanics and quantum statistical investigation

We present a combined quantum mechanics/molecular mechanics and quantum statistical investigation of the interactions between a Molecule (SO2) and an aerosol particle including rate constants for the uptake process. A coupled cluster/molecular mechanics method including explicit polarization is used along with a quantum statistical method for calculating sticking coefficients. The importance of the polarization of the classical subsystem (the aerosol particle), the size of the classical subsystem and the size of one-electron basis sets are studied. The interaction energy is divided into van der Waals, electrostatic and polarization contributions. Relevant binding sites for the evaluation of the sticking coefficient are identified. These are classified into three groups according to the strength of the molecule-aerosol particle interaction energy. The identification of binding sites provides relevant information used in the quantum statistical method and thereby knowledge of the magnitude of the sticking coefficients for the different binding sites along with the total rates for the uptake processes between the aerosol particle and the SO2 molecule

The EC-Earth3 Earth System Model for the Climate Model Intercomparison Project 6

Abstract. The Earth System Model EC-Earth3 for contributions to CMIP6 is documented here, with its flexible coupling framework, major model configurations, a methodology for ensuring the simulations are comparable across different HPC systems, and with the physical performance of base configurations over the historical period. The variety of possible configurations and sub-models reflects the broad interests in the EC-Earth community. EC-Earth3 key performance metrics demonstrate physical behaviour and biases well within the frame known from recent CMIP models. With improved physical and dynamic features, new ESM components, community tools, and largely improved physical performance compared to the CMIP5 version, EC-Earth3 represents a clear step forward for the only European community ESM. We demonstrate here that EC-Earth3 is suited for a range of tasks in CMIP6 and beyond