Statistical analysis of interplanetary shock waves measured by a Solar Wind Analyzer and a magnetometer onboard the Solar Orbiter Mission in 2023

TL;DR

This study analyzes interplanetary shock waves detected by Solar Orbiter in 2023, improving identification methods and examining their properties and distribution relative to the Sun.

Contribution

It introduces an enhanced semi-automated algorithm for identifying interplanetary shocks using Solar Orbiter data and provides a detailed statistical analysis of shock parameters and their variation with distance.

Findings

Over 40 shock waves identified in 2023.

Shock frequency increases with distance from the Sun.

Distribution of shock parameters analyzed statistically.

Abstract

Interplanetary (IP) shock waves are greatly interesting, as they represent significant phenomena in near-Earth space and are direct drivers of geomagnetic and radiation storms. Moreover, various data and parameters are being explored for the identification and characterization of these waves. The spatial dimensions of shock waves vary significantly with the conditions and parameters of the propagating medium. For example, the radii of curvature of the shock wave fronts can vary by several hundred Earth radii or more in the inner heliosphere. In this study, we improved the semi-automated identification of shock waves by analyzing the solar wind and IP magnetic field (MF) parameters. More precisely, we analyzed the data recorded by the Proton Alpha Sensor of the Solar Wind Analyzer (SWA-PAS) and magnetometer (MAG) onboard the Solar Orbiter (SolO) mission. These data were collected and analyzed during the SolO journey around the Sun in 2023 at distances of 0.29...0.95 AU. Employing the developed algorithm, we identified over 40 IP-shock waves that occurred in 2023 using SWA-PAS and MAG. Additionally, we determined and presented a list of shock types and their basic parameters, kinetic and magnetohydrodynamic. The compression ratios, plasma beta ${\beta}_{us}$, angle between the shock normal and upstream MF ${\theta}{_B}{_n}$, Mach number, and others were among these parameters. Furthermore, we investigated the statistical distributions of the ${\theta}{_B}{_n}$ and ${\beta}_{us}$ parameters in the upstream region. Finally, the dependence of number of the identified shock waves as a function of the distance away from the Sun was explored; the number of shocks increased gradually with the increasing heliocentric distance.