Advancement of Solar Wind Models and Mapping Magnetic Field Lines using Multi Spacecraft Observation

Kurzfassung

Understanding the structure and arrangement of the heliospheric magnetic field is significant for studies of the solar wind and its sources, as well as for understanding the magnetic field lines’ connection to the Sun and the transport of nonthermal particles from the Sun to Earth and beyond. We employ Tasnim et al. 2018’s [1] magnetohydrodynamic (MHD) solar wind (SW) model that includes the effects of solar wind acceleration, non-radial intrinsic magnetic fields and flows at the source surface/inner boundary, and conservation of angular momentum to predict the magnetic field as a function of position between the Sun and the Earth. We fit the model to near-Earth observations of the Wind spacecraft during the solar rotation period of 1 September – 28 September 2020 and estimate the solar wind plasma and magnetic field components from the inner boundary to 1 AU. To validate the above SW model, we compare predictions of density, ion temperature, radial and non radial magnetic field components close to the Sun with Parker Solar Probe data for the period. Figure 1 shows that Radial profiles of the predicted radial magnetic field Br (left) and non-radial/azimuthal magnetic field B_{\phi} (right) using Tasnim et al. 2018’s [1] model are consistent with the corresponding observations with increasing heliocentric distance. Agreement between the predictions and observations indicates the importance of incorporating intrinsic non radial velocity and magnetic field considerations from the inner boundary extending beyond 1 astronomical unit (AU) while upholding the crucial principle of angular momentum conservation. In addition, we extend the mapping approach of Tasnim et al. 2019 [2] into a robust and automated technique where field lines are mapped by stepping along the magnetic field B. This automated mapping capability allows us to map the magnetic field lines from the Sun to Earth for observational data from multiple spacecraft STEREO A, Wind, and ACE. The combined magnetic field and plasma data from STEREO-A and Wind allow the prediction of magnetic maps at longitudes from the Sun’s east limb to the disk center and from the disk center to the Sun’s west limb, respectively. The above SW model and the mapping approach provide us the scope to better understand space weather involving electromagnetic fields, plasma, and energetic particles from the Sun.