Magnetic Switchback Occurrence Rates in the Inner Heliosphere: Parker Solar Probe and 1 au

TL;DR

This study analyzes the occurrence rates of magnetic switchbacks in the inner heliosphere using Parker Solar Probe data, revealing a sharp decrease near 0.2 au and a gradual increase outward, with implications for understanding their generation mechanisms.

Contribution

It provides the first comprehensive analysis of switchback occurrence rates over eight PSP orbits and introduces a publicly available database of identified reversals.

Findings

Occurrence rate drops sharply near 0.2 au

Rate increases gradually beyond 0.2 au

Results are robust across different data cadences

Abstract

The subject of switchbacks, defined either as large angular deflections or polarity reversals of the magnetic field, has generated substantial interest in the space physics community since the launch of Parker Solar Probe (PSP) in 2018. Previous studies have characterized switchbacks in several different ways, and have been restricted to data available from the first few orbits. Here, we analyze the frequency of occurrence of switchbacks per unit distance for the first full eight orbits of PSP. In this work, are considered switchback only the events that reverse the sign of magnetic field relative to a regional average. A significant finding is that the rate of occurrence falls off sharply approaching the sun near 0.2 au (40 $R_\odot$), and rises gently from 0.2 au outward. The analysis is varied for different magnetic field cadences and for different local averages of the ambient field, confirming the robustness of the results. We discuss implications for the mechanisms of switchback generation. A publicly available database has been created with the identified reversals.