A Study on the geoeffective event of 11 April 2022

Coronal Mass Ejections (CMEs) are the main drivers of geomagnetic storms. Studying their initial phases is important for understanding their propagation through the heliosphere and the effects they have on the Space Weather. In this work, as a case study, we investigate how SolO/Metis observations improve the accuracy in modelling a geoeffective CME that occurred on 11 April 2022. This event caused a geomagnetic storm of intensity of −81 nT in terms of Disturbance Storm Time (Dst) on 14 April 2022. This moderately geoeffective event serves as a challenging case to model and understand the complex interactions of CMEs with the ambient solar wind. Using coronagraphic data from SOHO/LASCO C2, STEREO/SECCHI COR2-A along with VL observations from SolO/Metis, a Graduated Cylindrical Shell (GCS) analysis was done for 3D reconstruction of the CME flux rope. This provided the input parameters required for running the physics-based propagation models (DBM and DBEM, WSA-Enlil and EUHFORIA) which we have used to calculate the CME arrival times at Earth. SolO/Metis provides an additional viewpoint for the above analysis leading to a more precise determination of the GCS parameters and the 3D speed of the CME. By constraining the initial parameters, the 3D MHD models better resolve the interaction of the CME with the ambient solar wind. Including SolO/Metis data for this particular event leads to a lower error in the predicted arrival times at Earth for WSAEnlil and EUHFORIA (≈ 3 hours) than the typical ≈ 8–10 hours error estimates found in literature. Plain Language Summary Coronal Mass Ejections (CMEs) are large expulsions of plasma and magnetic field from the Sun. When directed towards Earth, these can affect the space environment around Earth. Accurate predictions of the arrival time of CMEs is therefore important to mitigate their effects. In this work, we chose a case study of a CME that erupted on April 11, 2022 and caused a moderate geomagnetic storm at Earth two days later, on April 13. The CME was observed by a constellation of spacecraft from different view points, which allowed building a 3D model of the CME during its initial evolution. We then employed three physics-based models to evaluate how the CME interacted and propagated through the ambient solar wind medium. We were then able to demonstrate the crucial role of the initial 3D model of the CME obtained from multi-viewpoint observations in improving the accuracy of the predictions of the arrival time at Earth.