Preparing AWI-CM3 for CMIP7: Implementing anthropogenic aerosol forcing (MACv2-SP)

Earth system modelling is an important instrument to investigate climate change in an integrated way, taking into account the interactions between the different compartments of the Earth system. It is also an important tool to perform climate projections for different climate scenarios in order to take appropriate mitigation and adaptation measures. Such climate simulations are coordinated internationally as part of the World Climate Research Programme’s (WCRP) Coupled Model Intercomparison Project Phase 7 (CMIP7).

Climate forcings are key for defining the main drivers of climate change in climate simulations. A very important aspect of the CMIP7 intercomparison is that all participating models were run under similar experimental conditions. In particular, in using the same climate forcings in the different models.

The Alfred Wegener Institute (AWI) will participate in the CMIP7 project with two state-of-the-art Earth system models AWI-CM3 and AWI-ESM3. This is being done as part of the German contribution to the Coupled Model Intercomparison Project (CAP7). The AWI contribution to CAP7 includes the adaptation of the AWI-CM3 model to be able to use different forcing data (such as greenhouse gases, solar forcing, O₃, and aerosol forcing) to fulfil the requirements of CMIP7. One task is therefore the implementation of the climate forcing dataset for anthropogenic aerosols MACv2-SP (currently available for CMIP6plus [Fiedler and Sudarchikova, 2024]) provided for CMIP7. For this purpose, an aerosol interface will be implemented in the AWI-CM3 climate model to read and process the aerosol forcing data provided by the MACv2-SP dataset.

In this presentation we will discuss the implementation of the MACv2-SP data into the AWI-CM3 climate model and present first results of the responses to these forcings.