The role of Alfv\'en wave dynamics on the large scale properties of the solar wind: comparing an MHD simulation with PSP E1 data

TL;DR

This paper models the solar wind during Parker Solar Probe's first orbit using MHD simulations that incorporate Alfvén wave dynamics, successfully reproducing observed large-scale plasma features and providing insights into the solar wind's behavior close to the Sun.

Contribution

The study introduces a comprehensive MHD simulation including Alfvén wave transport and dissipation to match in situ solar wind observations from PSP's first encounter.

Findings

Reproduces large-scale plasma parameters observed by PSP

Explains the amplitude of radial magnetic field and azimuthal velocities

Provides confidence in solar wind source modeling near the Sun

Abstract

During Parker Solar Probe's first orbit, the solar wind plasma has been observed in situ closer than ever before, the perihelion on November 6th 2018 revealing a flow that is constantly permeated by large amplitude Alfv\'enic fluctuations. These include radial magnetic field reversals, or switchbacks, that seem to be a persistent feature of the young solar wind. The measurements also reveal a very strong, unexpected, azimuthal velocity component. In this work, we numerically model the solar corona during this first encounter, solving the MHD equations and accounting for Alfv\'en wave transport and dissipation. We find that the large scale plasma parameters are well reproduced, allowing the computation of the solar wind sources at Probe with confidence. We try to understand the dynamical nature of the solar wind to explain both the amplitude of the observed radial magnetic field and of the azimuthal velocities.