Valliappan, Senthamizh Pavai ; Magdalenic, Jasmina

Poster presented at ESWW, Coimbra, Portugal on 2024-11-05

Abstract: The solar wind modelling study using the 3D MHD model EUHFORIA (EUropean Heliospheric FORecasting Information Asset, Pomoell & Poedts, 2018) at near the Sun distances show a large discrepancy between modelling results and in situ observations by Parker Solar Probe (PSP). The default coronal model used in EUHFORIA consists of the potential field source surface extrapolation (PFSS), Schatten current sheet (SCS) model and semi-empirical WSA model, which simulate the plasma and magnetic conditions at the inner boundary (0.1 AU). The outer boundary of the PFSS model, known as the source surface height parameter (RSS), and the inner boundary of the SCS model are among the free parameters in the coronal model that determine the area of modelled coronal holes, which in turn influences the area of open flux. In EUHFORIA, a default value of RSS = 2.6 R⊙ as suggested by McGregor et al. (2008) is used in the solar wind modelling at short radial distances. It is reported that lower RSS value in coronal models better captures the area of coronal holes (Asvestari et al., 2019), reconstructs small-scale features (Badman et. al., 2020), and represents coronal magnetic field topologies during different phases of solar cycles (Lee et al. 2011; Arden et al. 2014). In this study, we employ different values for the outer boundary of the PFSS model and inner boundary of the SCS model, while keeping default values for other parameters. We then compare the solar wind modelling results with varying RSS parameters to those obtained using all default parameters in the coronal model, by evaluating their agreement with the in situ observations from PSP for its first ten perihelion encounters.

Funding: 2INFRA_FED_SUNRISE/2INFRA_FED_SUNRISE/2INFRA_FED_SUNRISE