Abstract:

Coronal Mass Ejections (CMEs) are large-scale eruptions of plasma and magnetic elds from the Sun. They are considered to be the main drivers of strong space weather events at Earth. Multiple models have been developed over the past decades to be able to predict the propagation of CMEs and their arrival time at Earth. Such models require input from observations, which can be used to fit the CME to an appropriate structure. The team aims to focus on both CME observations as well as modeling and ultimately provide a benchmark of where the community stands on CME arrival time prediction. Such a benchmark is essential for scientists to improve existing models and/or create new models, as well as for tracking improvements arising from new observations. For such a project, it is crucial to bring together expertise from both the observational and the modeling communities.

When determining input parameters for CME propagation models, it is common procedure to derive kinematic parameters from remote-sensing data. The parameters resulting from such a fitting can be used as inputs for the CME propagation models in order to obtain an arrival prediction time of the CME f.e. at Earth. The international CME arrival time and impact working team 1 has been working on trying to assess the CME arrival time models and their impact predictions within the space weather community. Recently, the metrics for the validation has been established (see Verbeke et al. 2019). However, when fitting the CME structure to obtain the parameters needed in simulations, dierent geometric structures and also different parts of the CME structure can be fitted. These aspects, together with the fact that 3D reconstructions strongly depend on the subjectivity and judgement of the scientist performing them, may lead to uncertainties in the fitted parameters. Up to now, no large study has tried to map these uncertainties and to evaluate how they affect the modeling of CMEs. The team aims to obtain a better quantication of these errors.

This team will fit a large set of CMEs within a selected period of time so that uncertainties in the CME fittings can be investigated in detail. Each event will be fitted multiple times by different team members. This opens up the opportunity to discuss what exactly each person is fitting, as well as a possibility for statistics on uncertainties of the fittings. Furthermore, the fittings will be used to run the simulation models. A detailed evaluation of the models will be performed., where an initial validation is performed on the arrival time prediction capabilities of the models. Finally, this will set a benchmark for future models and model updates. Based on the methods described in Verbeke et al. 2019, the team will set up a database with the fittings and simulations, open for the community to use. If this team is selected for ISSI, it will provide a crucial forum to make substantial progress on quantifying the error in observational inputs as well as on creating a benchmark to evaluate CME arrival time prediction models against by using a well thought-out methodology and involving the international community.

Our team aims to achieve the following:

– Online database with GCS fittings of at least 20 CME events. Each event will have multiple fittings.

– Statistics and insight in the errors related to CME fittings: human errors, model errors, data errors,…

– Online metrics database and simulation runs input and output database

– Community benchmark for the current and future simulation models

– Online database with inputs and outputs of the simulation runs for all of the chosen CME events.