Multi-ensemble MHD coronal modeling to improve background wind for CME propagation for EUHFORIA 2.0

Space weather has the difficult task to try to anticipate the propagation of eruptive events such as coronal mass ejections (CMEs) in order to assess their possible impact on the Earth’s space environment. This requires an accurate description of the background in which CMEs propagate, mainly the continuum ejecta of particles that is the solar wind and the dynamo-generated heliospheric magnetic field. This proves challenging as the solar wind and dynamo magnetic field are interacting with each other depending on the activity cycle of our star, both at large and small scales. To be able to model accurately such a wide variety of scales and parameter regimes, the approach used by the EUHFORIA 2.0 project is to use a chain of models, taking advantage of existing codes to combine their strengths through numerical coupling across the heliosphere. The first step of this chain is the data-driven modeling of the inner corona, from photosphere measurements up until 0.1 AU, and it proves especially critical as it serves as boundary condition for the rest of the models.

In that regard, we will present here two coronal MHD models implemented as an alternative to the semi-empirical WSA and SCS models used so far in EUHFORIA. By using the COOLFluiD framework, we developed a new coronal model with implicit solving methods and unstructured meshes, which proves faster than traditional explicit methods on regular grids. We used the coronal code Wind-Predict to benchmark this new model for the simple polytropic approximation in the first place, and we present the similarities and differences obtained for data-driven configurations and compare them with observations (white-light images, coronal hole boundaries, in-situ data at 1 AU after coupling with EUHFORIA). We then present the improvements foreseen for each codes, especially for the heating terms: Wind-Predict will incorporate self-consistent Alfvén waves while COOLFluiD will use ad-hoc heating terms and a multi-species treatment. We will finally discuss the implications for the coupling with EUHFORIA and the CME propagation between 0.1 and 1 AU.

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870405 (EUHFORIA 2.0) and the ESA project "Heliospheric modelling techniques“ (Contract No. 4000133080/20/NL/CRS).