Superposed Epoch Analysis of the Energetic Electron Flux Variations During CIRs Measured by BD‐IES

Abstract

The flux variations of energetic electrons is one of the most important topics to understand dynamic processes in the space environment and the forecast for high-energy electron burst. BeiDa Image Electron Spectrometer (BD-IES), an imaging energetic elecstron spectrometer onboard a Chinese navigation satellite at an inclined geosynchronous orbit, can provide 50-600 keV electron flux data, which is used to investigate electron flux variations at GEO orbit during Co-rotating Interaction Region events (CIRs). The superposed epoch analysis is applied to study the electron flux variations in different energy channels of BD-IES during CIRs and the results support previous works. It reveals that electron fluxes in different channels all have a dropout before or at CIR interface and then the recovery of electrons with low energy reaches maximum earlier than that of electrons with high energy, with longer time differences for larger energy gap, which is consistent of two major mechanisms for energizing particles: inward radial diffusion and local acceleration. In addition, we investigate the relationship between electron flux enhancement in each energy channel and magnetic locals time and the extent of enhancement for electron flux peak value compared with average value before interface. These results can contribute to our understanding of electron flux variations at GEO during CIRs, and thus lay foundations for forecast research on high-energy electron enhancement during CIRs. Key Points: • Energetic electron flux variations at GEO during CIRs are studied using the observations from BD-IES, the first mid-energy electron detector in China • Superposed epoch analysis reveals that there are time delays between the peaks of low-and high-energy electron enhancements, with longer delay for larger energy gap • Relatively low-energy electrons tend to have MLT dependence during the enhancement process, while higher-energy electrons could reach an approximately equal level of enhancement in every MLT sector

Examination of Radiation Belt Dynamics During Substorm Clusters: Activity Drivers and Dependencies of Trapped Flux Enhancements

“…One example of this approach is the use of superposed epoch analysis to focus electron flux decreases termed “dropouts,” seen in GPS data, following high speed streams (Morley et al., 2010), and subsequently examined using low‐Earth POES observations (Meredith et al., 2011, Hendry et al., 2012). The value of similar approaches has been demonstrated more recently in multiple studies, examples being: using Van Allen Probes to investigate the impact of differing drivers (Katsavrias, Daglis, & Li, 2019) and separating adiabatic and nonadiabatic effects (Murphy et al., 2018), MLT‐resolved dynamics using POES measurements around substorm cluster events (Rodger et al., 2019), GPS‐measured changes in electron fluxes during EMIC scattering events (Hendry et al., 2021), and BD‐IES observed electron flux variations during high speed streams (Yin et al., 2019).…”

“…demonstrated more recently in multiple studies, examples being: using Van Allen Probes to investigate the impact of differing drivers (Katsavrias, Daglis, & Li, 2019) and separating adiabatic and nonadiabatic effects (Murphy et al, 2018), MLT-resolved dynamics using POES measurements around substorm cluster events (Rodger et al, 2019), GPS-measured changes in electron fluxes during EMIC scattering events (Hendry et al, 2021), and BD-IES observed electron flux variations during high speed streams (Yin et al, 2019).…”

Characteristics of Electron Precipitation Directly Driven by Poloidal ULF Waves

“…These precipitating energy fluxes are also comparable to those induced by hiss waves during disturbed conditions (∼0.3–1 $$\mathrm{e}\mathrm{r}\mathrm{g}\cdot \mathrm{c}{\mathrm{m}}^{-2}\cdot {\mathrm{s}}^{-1}$$, Ma et al., 2021). Note that this comparison is rather inaccurate, since the simulation results largely depend on the electron distribution before the ULF wave occurrence, which could be enhanced significantly during geomagnetic storms and/or substorms (Kataoka & Miyoshi, 2006; McPherron, 1979; Yin et al., 2019). The enhanced source population could in turn lead to enlarged precipitation and therefore an enhanced ground‐based response.…”

Medium‐Energy Electron Detector Onboard the FY‐3E Satellite

“…The pin‐hole imaging sensor head with a spin‐stabilized satellite platform can provide three‐dimensional measurements of medium‐energy electrons. A similar pin‐hole imaging sensor head design has been successfully used in the BeiDa imaging electron spectrometer (BD‐IES) and energetic electron detection package (EEDP) deployed on Chinese navigation satellites to achieve multi‐directional measurements of medium‐energy electrons in medium Earth orbit (MEO) and geosynchronous equatorial orbit (GEO) (Chen, Zong, Zou, Wang, et al., 2020; Chen, Zong, Zou, Zhou, et al., 2020; Hao et al., 2020; Li, Zhou, Zong, Chen, et al., 2017; Li, Zhou, Zong, Rankin, et al., 2017; Liu et al., 2018; Wang et al., 2017; Ye et al., 2021; Yin et al., 2019; Zong et al., 2016, 2018; Zou et al., 2018, 2019). All of these satellites are three‐axis‐stabilized platforms.…”