Backmapping of the High- and Low-latitude Solar Wind under Multiple Heliospheric and Coronal Magnetic Field Configurations

TL;DR

This study evaluates how different heliospheric and coronal magnetic field models affect solar wind backmapping accuracy, revealing model sensitivities and implications for understanding high- and low-latitude solar wind origins.

Contribution

It systematically compares multiple HMF and CMF models to quantify their impact on backmapping uncertainties, especially at high latitudes.

Findings

Fisk and Parker HMF models show similar magnetic field predictions but differ in footpoint locations.

CMF models produce minor variations for high/mid-latitude wind but diverge for low-latitude wind.

High/mid-latitude wind sources are linked to active regions or coronal holes, while some low-latitude wind originates from quiet Sun regions.

Abstract

Solar wind backmapping is a critical technique for analyzing the origin of the solar wind and space weather events by correlating in situ measurements with solar remote-sensing observations. This technique typically traces magnetic field lines using a heliospheric magnetic field (HMF) model coupled with a coronal magnetic field (CMF). However, the impact of different HMF and CMF configurations on backmapping uncentainty-particularly regarding high-latitude solar wind-remains inadequately quantified. This study comprehensively evaluates solar wind backmapping by combining two HMF models (Parker spiral, Fisk-type) with three CMF models (Potential Field Source Surface (PFSS), Potential Field Current Sheet (PFCS), Current Sheet Source Surface (CSSS)). Our analysis primarily uses in situ measurements from Ulysses and remote-sensing data from STEREO-A. Key findings are that: (1) while both Fisk and Parker HMF models show comparable consistency with measured magnetic field strength and polarity, they produce certain longitudinal displacements in their back-mapped footpoints on the source surface (2.5$R_{\odot}$); (2) For CMF models (PFSS, PFCS, CSSS), predicted photospheric footpoints exhibit minor variations for high/mid-latitude solar wind but some divergences for ecliptic/low-latitude wind; (3) All three CMF models link high/mid-latitude wind to active regions or coronal holes, yet associate a fraction of ecliptic/low-latitude wind with quiet-Sun regions; (4) Ecliptic/low-latitude sources show significantly stronger dependence on the PFSS source surface height compared to high-latitude wind. These results demonstrate that simpler models (PFSS + Parker) appear reasonably adequate for polar coronal hole wind studies, while low-latitude/ecliptic solar wind exhibits the heightened sensitivity to model choices.