On the loss mechanisms of radiation belt electron dropouts during the 12 September 2014 geomagnetic storm

Abstract

The loss mechanisms of radiation belt dropout during the 12 September 2014 storm were investigated using satellite measurements q During the initial phase of the storm, magnetopause shadowing was the dominant loss mechanism, supported by energyindependent decay and butterfly pitch angle distributions (PADs) q The wave-particle interactions played an important role in >1 MeV electron loss during the main phase of the storm and produced 90-peaked PADs at L < 4

Prediction of Dynamic Plasmapause Location Using a Neural Network

“…interactions inside and outside the plasmapause are quite different due to the sharp change in plasma density, the prediction of the plasmapause location becomes very important for magnetospheric research (e.g., Hua et al, 2020b;Khoo et al, 2018Khoo et al, , 2019Ni et al, 2015;Ma et al, 2020;Summers et al, 2008;Xiang et al, 2020;Zhang et al, 2018Zhang et al, , 2019.…”

“…The plasmasphere, which is full of cold and dense plasma (electrons ~ 1 eV with density ~ 10 2 -10 4 cm -3 ), plays an important role in modulating the fluxes of energetic particles in the Earth's ring current and radiation belts (e.g., Cao et al, 2017;Darrouzet et al, 2009;Fu et al, 2020;Gu et al, 2011Gu et al, , 2012Gu et al, , 2020Hua et al, 2019;Kozyra et al, 1995;Lemaire and Gringauz, 1998;Ni et al, 2013;Orr and Webb, 1975;Sandel et al, 2003;Takahashi and Anderson, 1992;Webb and Orr, 1975;Yi et al, 2021;Zhou et al, 2020). The plasmasphere strongly influences the plasma properties of the inner magnetosphere by wave-particle interactions (e.g., Fu et al, 2016;Gary et al, 1994;Hua et al, 2020a;Ni et al, 2014Ni et al, , 2017Thorne and Horne, 1992;Wilson et al, 1992;Xiang et al, 2018;Young et al, 1981), and contributes to assessing the low-latitude boundary layer and plasma sheet (e.g., Cao et al, 2016;Elphic et al, 1997).…”

“…The variation of L pp responds considerably to the changes of solar wind forcing and geomagnetic activity (e.g., Goldstein et al., 2003; Liu et al., 2015). Because the plasmapause is related to the plasmasphere, the ring current, and the radiation belts in the inner magnetosphere, where the wave‐particle interactions inside and outside the plasmapause are quite different due to the sharp change in plasma density, the prediction of the plasmapause location becomes very important for magnetospheric research (e.g., Hua et al., 2020b; Khoo et al., 2018, 2019; Ma et al., 2020; Ni et al., 2015; Summers et al., 2008; Xiang et al., 2020; Zhang et al., 2018, 2019).…”

Modeling the Dynamics of Radiation Belt Electrons With Source and Loss Driven by the Solar Wind

“…During active times, both magnetopause shadowing followed by outward radial diffusion and atmospheric precipitations due to wave‐induced pitch angle diffusion play important roles in the loss of radiation belt electrons (e.g., Li et al., 1997; Ma et al., 2020; Morley et al., 2010; Tu et al., 2010; Turner et al., 2012; Xiang et al., 2016). The inward movement of the magnetopause due to strong solar wind dynamic pressure ( P dyn ) can substantially deplete electrons at high L shells where electrons find themselves on open drift shells, which is called magnetopause shadowing (e.g., Shprits, Thorne, Friedel et al., 2006).…”

Non-storm erosion of MeV electron outer radiation belt down to <em>L</em>* &lt; 4.0 associated with successive enhancements of solar wind density

“…Recent studies have shown that outer belt electrons can also exhibit dramatic losses (Morley et al, 2010; Ni BB et al, 2013; Su ZP et al, 2014, 2016; Katsavrias et al, 2015; Engebretson et al, 2018; Tu WC et al, 2019, Ma X et al, 2020) and accelerations (Su ZP et al, 2015) during non‐storm periods. Losses of MeV electrons can be attributed to either adiabatic processes (the Dst effect during enhancement of the ring current (Kim and Chan, 1997) or non‐adiabatic processes.…”