The Occurrence and Prevalence of Magnetic Reconnection in the Kelvin‐Helmholtz Instability Under Various Solar Wind Conditions

Abstract

As the shocked solar wind flows past the flank magnetopause, surface waves can form and roll up into flow vortices. This is known as the Kelvin‐Helmholtz Instability, which is thought to be an important mechanism whereby energy and momentum are transferred from the solar wind into the magnetosphere. One mechanism whereby this can occur is magnetic reconnection in the equatorial plane on compressed current sheets between vortices. In 2015, the NASA Magnetospheric Multiscale (MMS) mission observed this form of in‐plane reconnection during a KHI event in the post‐noon sector of the dayside magnetopause. We use data from MMS to investigate 12 KHI events at different positions along the magnetospheric flanks. For each event, we identify periodic compressed current sheets and perform Walén tests for each to identify reconnection jets. We then investigate the fraction of current sheets that exhibit reconnection signatures, and refer to it as the “event ratio.” Results show that the event ratio decreases for events further down the magnetospheric flanks. Additionally, we investigate solar wind parameters during each event and find that the event ratio increases with an increasing northward component of the interplanetary magnetic field.This article is protected by copyright. All rights reserved.

Density and Magnetic Field Asymmetric Kelvin‐Helmholtz Instability

“…The Kelvin-Helmholtz (KH) instability is driven by a large sheared flow (Chandrasekhar, 1961), which is an important physical mechanism for the viscous-like interaction between the Earth's magnetosphere (MSP) and the solar wind (SW) (Axford, 1964;Axford & Hines, 1961). There are lots of in-situ observation events during both north-and southward interplanetary magnetic field (IMF) conditions at low-latitudes (Blasl et al, 2022;Eriksson, Lavraud, et al, 2016;Henry et al, 2017;Hwang et al, 2011;Kavosi et al, 2023;Li et al, 2013Li et al, , 2016Li et al, , 2023Rice et al, 2022;Wilder et al, 2023;Yan et al, 2014Yan et al, , 2022, as well as at high latitudes with IMF mostly along the dawn or dusk direction (Hwang et al, 2012;Ma et al, 2016;Nykyri et al, 2021). Kavosi and Raeder (2015) shows that for Earth's magnetopause, KH waves occur about 19% of the time.…”