Equatorwards Expansion of Unperturbed, High-Latitude Fast Solar Wind

TL;DR

This study uses dual-site radio observations to analyze the high-latitude fast solar wind, revealing an equatorward deviation in flow direction during Solar Cycle 23's declining phase.

Contribution

It provides new observational evidence of the equatorward expansion of high-latitude fast solar wind using dual-site IPS measurements.

Findings

Fast solar wind shows a 3-4° equatorward deviation.

Deviation observed in both hemispheres.

Results consistent across different times in Solar Cycle 23.

Abstract

We use dual-site radio observations of interplanetary scintillation (IPS) with extremely long baselines (ELB) to examine meridional flow characteristics of the ambient fast solar wind at plane-of-sky heliocentric distances of 24-85 solar radii (R\odot). Our results demonstrate an equatorwards deviation of 3-4{\deg} in the bulk fast solar wind flow direction over both northern and southern solar hemispheres during different times in the declining phase of Solar Cycle 23.