Turbulent Energy Transfer at Dipolarization Fronts

Abstract

Dipolarization fronts (DFs), ion‐scale magnetic transients characterized by dramatic enhancement of northward magnetic field, have been documented as crucial energy transfer regions in the magnetosphere. DF‐driven energy transfer has hitherto been studied mainly in the laminar regime. Energy transfer driven by turbulent processes, however, remains unclear. Here we perform a comprehensive investigation of turbulent energy transfer (TET) developed at DFs, via using high‐cadence data from Magnetospheric Multiscale mission. We find that: (a) TET is equally governed by energy loads and generators, different from laminar energy transfer which is typically dominated by energy loads; (b) ion and electron currents play comparable roles in driving TET; (c) TET is positively correlated with local magnetic field strength and ion speed; (d) TET shows asymmetric global distributions along the dawn‐dusk direction. These features implicate that TET is primarily related to electromagnetic turbulence at electron‐ion hybrid scales. These new results, uncovering unique characteristics of DF‐driven TET, can deeply advance our understanding of energy budgets in the magnetosphere.

Extended Energy Conversion and Electron Acceleration Behind Dipolarization Front

“…• Persistent energy conversion extended far (∼10 d DF ) behind a dipolarization front is presented • The persistent energy conversion was developed inside a decaying flux pileup region and driven by electron currents assumed to host negligible energy conversion, and the BBF-driven energy transport is mainly attributed to energy conversion developed locally at the DFs (e.g., Angelopoulos et al, 2013;C. M. Liu et al, 2023bC.…”

Magnetic Hump Associated with Electron Vortex at Dipolarization Front

“…There sometimes exist kinetic-scale magnetic dips prior to the DFs (Yao et al 2013), attributed to dawnward current carried by either reflected ions (Zhou et al 2014) or electrons (Huang et al 2022). DFs and their adjacent regions are closely associated with various types of plasma waves, such as whistler waves (Hwang et al 2014;Viberg et al 2014;Chen et al 2021Chen et al , 2022, lower hybrid drift waves (Zhou et al 2009;Divin et al 2015;Chen et al 2021), and high-frequency electrostatic waves (Zhou et al 2009;Zhang & Angelopoulos 2014;Yang et al 2017;Chen et al 2022), which can heat and accelerate electrons, and result in energy conversion (Huang et al 2015;Khotyaintsev et al 2017;Liu et al 2023). DFs are sometimes unstable to the interchange instability, which can produce finger-like/bubble magnetic structures together with electron jets around them and an alternating duskward and dawnward electric field (Pritchett & Coroniti 2010;Yu et al 2022).…”

Direct Observations of Reconnection Fronts in Earth's Turbulent Magnetosheath

“…After being generated inside the diffusion region, RFs can propagate as coherent structures during their interactions with ambient plasma (e.g., Runov et al 2009;Liu et al 2022a), thus facilitating cross-scale energy transport. The interaction between the RFs and ambient plasma usually leads to intense energy transfer, which has been studied both numerically and experimentally, revealing that energy loads contributed mainly by ion currents typically dominate (e.g., Angelopoulos et al 2013;Lapenta et al 2014;Huang et al 2015;Yao et al 2017;Liu et al 2018Liu et al , 2022bLiu et al , 2023Lu et al 2018;Zhong et al 2019;Wang et al 2020;Shu et al 2021). The RF-driven energy transfer is usually manifested in the form of particle heating and acceleration (e.g., Fu et al 2020;Birn et al 2013;Duan et al 2014;Runov et al 2015;Gabrielse et al 2016;Lu et al 2016;Zhou et al 2018;Liu et al 2017) and wave/turbulence generation (e.g., Zhou et al 2009;Khotyaintsev et al 2011;Huang et al 2012;Hwang et al 2014;Divin et al 2015;Deng et al 2010;Liu et al 2019).…”