Magnetic connectivity from the Sun to the Earth with MHD models I. Impact of the magnetic modelling for connectivity validation

TL;DR

This study evaluates the effectiveness of MHD models in mapping magnetic connectivity from the Sun to Earth, showing they perform comparably to traditional methods and can be improved with enhanced physics integration.

Contribution

The paper introduces a combined MHD modeling approach for magnetic connectivity validation, analyzing uncertainties and comparing results with observational data during different solar activity periods.

Findings

MHD models show 19%-100% overlap with coronal holes.

Polarity agreement ranges from 36%-69%.

Uncertainties affect connectivity and polarity estimations.

Abstract

This article discusses the magnetic connectivity between the Sun and the Earth, which is essential for understanding solar wind and space weather events. Due to limited direct observations, reliable simulations are necessary. The most commonly used method is the two-step ballistic method, but it has many free parameters that affect the results. The authors propose a method based on self-consistent magnetohydrodynamic (MHD) models. They combine the COCONUT coronal model with the EUHFORIA heliospheric model to compute magnetic field lines from the Earth to the Sun and quantify spatial and temporal uncertainties. To validate their method, they analyze four events associated with high-speed streams from well-identified coronal holes. The results show partial overlap with the assumed coronal holes of origin, ranging from 19% to 100% depending on the event. They also examine the magnetic polarity observed on Earth, finding that MHD simulations provide a good polarity estimation, with agreement ranging from 36% to 69% across the events. Spatial and temporal uncertainties explain the mixed results for some cases. MHD models appear more effective during periods of maximum solar activity due to the latitudinal extent of the heliospheric current sheet (HCS). The authors conclude that MHD models offer results as good as the two-step ballistic method, with potential for improvement as more critical physics are integrated into the models.