The HAM-M7 aerosol scheme within OpenIFS 48r1: developing EC-Earth4

The HAM-M7 aerosol scheme within OpenIFS 48r1: developing EC-Earth4

 

Lianghai Wu*, Eemeli Holopainen,Tommi Bergman, Twan van Noije, Philippe Le Sager, Ramiro Checa-Garcia, Xuemei Wang, Adrian Hill, Marcus Koehler, Harri Kokkola, Anton Laakso, Vincent Huijnen

 

*Royal Netherlands Meteorological Institute, 3730 AE De Bilt, the Netherlands

 

We implemented a new interactive aerosol module as part of the OpenIFS 48r1. The module is based on the Hamburg Aerosol Module (HAM) version 2.3 with at its core the M7 microphysics scheme. By representing aerosol in multiple modes, the M7 scheme enables a detailed description of aerosol particle characteristics, optical properties, and aerosol-cloud interactions. The new module will be used in the Earth system model EC-Earth 4 to improve the modelling of the life cycle of anthropogenic and natural aerosols, their direct and indirect radiative effects, and to deepen our understanding of their influence on climate change and weather patterns.

 

The implementation presented several challenges including a significant jump of five IFS cycles from the initial implementation in OpenIFS 43r3 to the presented implementation in 48r1, the coupling between other key modules such as the radiative transfer kernel (ecRad), cloud scheme and existing chemistry modules, and missing parallelization and restartability functionality. Additionally, the lack of a prior reference implementation to evaluate the performance of the implemented scheme added to the complexity. To address these challenges, we reviewed the entire model workflow, including emissions, removal processes (sedimentation, wet and dry deposition), optical properties, and diagnostics, to identify and resolve performance issues.

 

In this presentation, we will share our progress and the latest global aerosol simulation results driven by the emissions from the Copernicus Atmosphere Monitoring Service (CAMS). We will highlight the global distribution of aerosol properties, including mass concentrations, aerosol removal fluxes, and aerosol optical depth, along with preliminary evaluation against independent observations. We identify missing elements which require further improvements.