Quantifying the Contribution of Microbursts to Global Electron Loss in the Radiation Belts

Greeley, A. D.; Kanekal, S. G.; Baker, D. N.; Klecker, B.; Schiller, Q.

doi:10.1029/2018ja026368

Cited by 24 publications

(32 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, they did show a magnitude variation in the L range, L = 3–8 (Blum et al, ). In contrast, Greeley et al () found average microburst intensities were higher in the afternoon MLT region when compared to the morning MLT region.…”

Section: Introductionmentioning

confidence: 82%

“…In this study we use the HILT instrument onboard the SAMPEX to study microbursts. SAMPEX observations have been widely used previously in relativistic microburst investigations (e.g., Nakamura et al, ; Lorentzen et al, ; Greeley et al, ), and the O'Brien et al () detection algorithm (discussed in the following section) was specifically developed for use with SAMPEX measurements, where there is a long time series of measurements available. The HILT instrument is capable of measuring >1.05‐MeV electrons and >5‐MeV protons (Klecker et al, ).…”

Section: Instrumentationmentioning

confidence: 99%

“…Based on these relatively new studies, Breneman et al (2017), Greeley et al (2019), and Seppälä et al (2018), we now know that relativistic microbursts are not only a significant loss process from the electron radiation belts but also a significant driver of chemical changes and subsequently ozone loss in the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Characteristics of Relativistic Microburst Intensity From SAMPEX Observations

et al. 2019

View full text Add to dashboard Cite

Relativistic electron microbursts are an important electron loss process from the radiation belts into the atmosphere. These precipitation events have been shown to significantly impact the radiation belt fluxes and atmospheric chemistry. In this study we address a lack of knowledge about the relativistic microburst intensity using measurements of 21,746 microbursts from the Solar Anomalous Magnetospheric Particle Explorer (SAMPEX). We find that the relativistic microburst intensity increases as we move inward in L, with a higher proportion of low‐intensity microbursts (<2,250 [MeV cm2 sr s]−1) in the 03–11 magnetic local time region. The mean microburst intensity increases by a factor of 1.7 as the geomagnetic activity level increases and the proportion of high‐intensity relativistic microbursts (>2,250 [MeV cm2 sr s]−1) in the 03–11 magnetic local time region increases as geomagnetic activity increases, consistent with changes in the whistler mode chorus wave activity. Comparisons between relativistic microburst properties and trapped fluxes suggest that the microburst intensities are not limited by the trapped flux present alongside the scattering processes. However, microburst activity appears to correspond to the changing trapped flux; more microbursts occur when the trapped fluxes are enhancing, suggesting that microbursts are linked to processes causing the increased trapped fluxes. Finally, modeling of the impact of a published microburst spectra on a flux tube shows that microbursts are capable of depleting <500‐keV electrons within 1 hr and depleting higher‐energy electrons in 1–23 hr.

show abstract

Section: Introductionmentioning

confidence: 82%

Section: Instrumentationmentioning

confidence: 99%

See 1 more Smart Citation

Characteristics of Relativistic Microburst Intensity From SAMPEX Observations

et al. 2019

View full text Add to dashboard Cite

show abstract

“…However, during the main phase, as substorm activity increases and the convection electric field is enhanced, the hot electron density increases in the near-Earth plasma sheet, and higher energy electrons have greater access to the dawnside of the inner magnetosphere via open drift paths from the plasma sheet. Greeley et al (2019) showed using SAMPEX data that recovery phase microbursts, particularly during CME-driven storms, can significantly contribute to global radiation belt electron loss. Open drift paths change to closed drift paths for some of these tens of keV electrons, and a more symmetric, trapped electron ring current can develop.…”

Section: Discussionmentioning

confidence: 99%

The Storm Time Development of Source Electrons and Chorus Wave Activity During CME‐ and CIR‐Driven Storms

et al. 2019

View full text Add to dashboard Cite

Whistler mode chorus waves influence the dynamics of the Earth's radiation belts and the inner magnetosphere through gyroresonant wave particle interactions. Chorus waves are generated by anisotropic hot electrons from a few to tens of keV, called source electrons, which have increased access from the nightside plasma sheet to the inner magnetosphere during geomagnetic storms. The primary drivers of geomagnetic storms are coronal mass ejections (CMEs) and corotating interaction regions (CIRs). Through differences in their characteristic physical parameters, they can each impact the nightside plasma sheet differently. Using Van Allen Probes observations, we have conducted a superposed epoch analysis of chorus wave activity and source electron development across all local times between L = 2–6 during 25 CME‐ and 35 CIR‐driven storms. The superposed epoch analysis shows that chorus wave power follows the storm phase‐dependent access of the source electron population. Chorus waves and source electrons are observed on the dawnside during the main phase, when open drift path access via eastward convective drift from the plasma sheet is enhanced. During the recovery phase, chorus waves and source electrons are observed at all magnetic local times with low intensities, exemplifying the formation of a weak symmetric, trapped electron population. A linear theory approximation for wave growth from source electron observations shows that increased wave growth follows the enhanced source electrons during each storm phase. CME and CIR storms display similar behavior and levels of average wave power; however, chorus wave activity reaches lower L‐shells during CME storms on average.

show abstract

“…How do they correlate with loss of outer belt electrons? Greeley et al () in this collection find that the microburst to global loss coupling is predominant in the quasi‐trapped population of radiation belt electrons (i.e., electrons performing less than one full drift before being precipitated) while having negligible influence on the untrapped and stably trapped populations. Previous estimates of microburst flux levels are not well constrained, and further studies are needed to refine these estimates, which can then be incorporated more accurately into radiation belt models (section ).…”

Section: Particle Loss In the Inner And Outer Zonesmentioning

confidence: 94%

Particle Dynamics in the Earth's Radiation Belts: Review of Current Research and Open Questions

et al. 2020

View full text Add to dashboard Cite

The past decade transformed our observational understanding of energetic particle processes in near‐Earth space. An unprecedented suite of observational systems was in operation including the Van Allen Probes, Arase, Magnetospheric Multiscale, Time History of Events and Macroscale Interactions during Substorms, Cluster, GPS, GOES, and Los Alamos National Laboratory‐GEO magnetospheric missions. They were supported by conjugate low‐altitude measurements on spacecraft, balloons, and ground‐based arrays. Together, these significantly improved our ability to determine and quantify the mechanisms that control the buildup and subsequent variability of energetic particle intensities in the inner magnetosphere. The high‐quality data from National Aeronautics and Space Administration's Van Allen Probes are the most comprehensive in situ measurements ever taken in the near‐Earth space radiation environment. These observations, coupled with recent advances in radiation belt theory and modeling, including dramatic increases in computational power, have ushered in a new era, perhaps a “golden era,” in radiation belt research. We have edited a Journal of Geophysical Research: Space Science Special Collection dedicated to Particle Dynamics in the Earth's Radiation Belts in which we gather the most recent scientific findings and understanding of this important region of geospace. This collection includes the results presented at the American Geophysical Union Chapman International Conference in Cascais, Portugal (March 2018) and many other recent and relevant contributions. The present article introduces and review the context, current research, and main questions that motivate modern radiation belt research divided into the following topics: (1) particle acceleration and transport, (2) particle loss, (3) the role of nonlinear processes, (4) new radiation belt modeling capabilities and the quantification of model uncertainties, and (5) laboratory plasma experiments.

show abstract

Quantifying the Contribution of Microbursts to Global Electron Loss in the Radiation Belts

Cited by 24 publications

References 80 publications

Characteristics of Relativistic Microburst Intensity From SAMPEX Observations

Characteristics of Relativistic Microburst Intensity From SAMPEX Observations

The Storm Time Development of Source Electrons and Chorus Wave Activity During CME‐ and CIR‐Driven Storms

Particle Dynamics in the Earth's Radiation Belts: Review of Current Research and Open Questions

Contact Info

Product

Resources

About