Relativistic microburst storm characteristics: Combined satellite and ground-based observations

Dietrich, Sarah; Rodger, Craig J.; Clilverd, Mark A.; Bortnik, J.; Raita, Tero

doi:10.1109/ursigass.2011.6051070

Cited by 5 publications

(5 citation statements)

References 36 publications

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“…In this case, the electron is very likely lost. The BLC region estimated by this method closely matches the BLC region shown in Comess et al (2013, Figure 1) and Dietrich et al (2010, Figure 3) for other LEO satellites. Lastly, we repeated the same analysis using the Tsyganenko (1989) model, which yielded similar BLC boundaries.…”

Section: Methodssupporting

confidence: 86%

Statistical Properties of Electron Curtain Precipitation Estimated With AeroCube‐6

et al. 2020

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Curtain precipitation is a recently discovered stationary, persistent, and latitudinally narrow electron precipitation phenomenon in low Earth orbit. Curtains are observed over consecutive passes of the dual AeroCube-6 CubeSats while their in-track lag varied from a fraction of a second to 65 s, with dosimeters that are sensitive to >35-keV electrons. This study uses the AeroCube-6 mission to quantify the statistical properties of 1,634 curtains observed over 3 years. We found that many curtains are narrower than 10 km in the latitudinal direction with 90% narrower than 20 km. We examined the geographic, magnetic local time, and geomagnetic dependence of curtains. We found that curtains are observed in the late-morning and premidnight magnetic local times, with a higher occurrence rate at premidnight, and curtains are observed more often during times of enhanced Auroral Electrojet. We found a few curtains in the bounce loss cone region above the North Atlantic, whose electrons were continuously scattered for at least 6 s. Such observations suggest that continuous curtain precipitation may be a significant loss of >35-keV electrons from the magnetosphere into the atmosphere. We hypothesize that the curtains observed in the bounce loss cone were accelerated by parallel electric fields, and we show that this mechanism is consistent with the observations. Plain Language Summary Electron curtain precipitation from space into Earth's atmosphere is a recently discovered phenomenon observed by dual-spacecraft missions such as the AeroCube-6 CubeSats that are nearly in the same orbit, ≈700 km above Earth's surface. Curtains appear stationary between consecutive passes of the AeroCube-6 CubeSats, while the leader CubeSat was ahead of the follower CubeSat by up to a minute in orbital time. Curtains are also very narrow along the satellite orbit that is mostly in the latitudinal direction. Besides these two properties, curtains and their impact on the magnetosphere and atmosphere are not well understood. Therefore, we used the AeroCube-6 mission that took data together for 3 years to statistically quantify curtain properties and to better understand their origin. We found 1,634 curtains and found that 90% of curtains are narrower than 20 km in the latitudinal direction, curtains are observed on the outer radiation belt field lines predominately in the antisunward region, and curtains are observed when the magnetosphere is disturbed. Curtains observed in a special region above the North Atlantic shed light on their origin. A surprising result is that a few dozen curtains observed in this North Atlantic region were continuously precipitating into the atmosphere for multiple seconds. Therefore, curtains may be a significant source of atmospheric ionization responsible for the natural depletion of ozone. Electron curtain precipitation is observed in low Earth orbit (LEO) and appears stationary in latitude. Curtains were recently discovered by Blake and O'Brien (2016) using the >35-keV electron dosimeters onboard the dual AeroCub...

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Section: Methodssupporting

confidence: 86%

Statistical Properties of Electron Curtain Precipitation Estimated With AeroCube‐6

et al. 2020

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“…This algorithm identified 11,866 and 10,789 microburst candidates on FU3 and FU4, respectively. To reduce the effect of background precipitation and ensure that observations were of recently scattered microbursts, these events were further restricted to the region of the North Atlantic conjugate to the South Atlantic Anomaly, often referred to as the Bounce Loss Cone (BLC) region, similar to previous studies (e.g., Comess et al, 2013;Dietrich et al, 2010). Particles observed at FIREBIRD's altitude in this region have a conjugate mirror point in the southern hemisphere below 100 km.…”

Section: Event Selectionmentioning

confidence: 99%

The Energy Spectra of Electron Microbursts Between 200 keV and 1 MeV

et al. 2021

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This study investigates the energy spectrum of electron microbursts observed by the Focused Investigations of Relativistic Electron Burst Intensity, Range, and Dynamics II (FIREBIRD‐II, henceforth FIREBIRD) CubeSats. FIREBIRD is a pair of CubeSats, launched in January 2015 into a low Earth orbit, which focuses on studying electron microbursts. High‐resolution electron data from FIREBIRD‐II consist of 5 differential energy channels between 200 keV and 1 MeV and a >1 MeV integral channel. This covers an energy range that has not been well studied from low Earth orbit with good energy and time resolution. This study aims to improve the understanding of the scattering mechanism behind electron microbursts by investigating their spectral properties and their relationship with the equatorial electron population under different geomagnetic conditions. Microbursts are identified in the region of the North Atlantic where FIREBIRD only observes electrons in the bounce loss cone. The electron flux and exponential energy spectrum of each microburst are calculated using a FIREBIRD instrument response modeled in GEANT4 (GEometry ANd Tracking) and compared with the near‐equatorial electron spectra measured by the Van Allen Probes. Microbursts occurring when the Auroral Electrojet (AE) index is enhanced tend to carry more electrons with relatively higher energies. The microburst scattering mechanism is more efficient at scattering electrons with lower energies; however, the difference in scattering efficiency between low and high energy is reduced during periods of enhanced AE.

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“…This study uses the electron flux values from MagEIS in the range from 200 to 1,200 keV to mimic the FIREBIRD energy range and in the pitch angle bin closest to the loss cone. To reduce the effect of background precipitation and ensure that observations were of recently scattered microbursts, these events were further restricted to the region of the North Atlantic conjugate to the South Atlantic Anomaly, often referred to as the Bounce Loss Cone (BLC) region, similar to previous studies (e.g., Comess et al, 2013;Dietrich et al, 2010). Particles observed at FIREBIRD's altitude in this region have a conjugate mirror point in the southern hemisphere below 100 km.…”

Section: Instrument Descriptionmentioning

confidence: 99%

The Energy Spectra of Electron Microbursts Between 200 keV and 1 MeV

Johnson

Shumko

Sample

et al. 2021

Preprint

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Microbursts are short intensifications of electron precipitation into the atmosphere lasting up to a few hundred milliseconds. The term microburst was first used by Anderson and Milton (1964) to describe enhancements in balloon observations of 𝐴𝐴 ≤ 100 keV bremsstrahlung X-rays caused by electrons impacting the atmosphere. Later, balloon observations up to 300 keV revealed microbursts to be a significant loss process in the dayside magnetosphere (Parks, 1978). More recently, relativistic ( 𝐴𝐴 𝐴 1 MeV) electron microbursts have been observed in situ by the spacecraft (

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Relativistic microburst storm characteristics: Combined satellite and ground-based observations

Cited by 5 publications

References 36 publications

Statistical Properties of Electron Curtain Precipitation Estimated With AeroCube‐6

Statistical Properties of Electron Curtain Precipitation Estimated With AeroCube‐6

The Energy Spectra of Electron Microbursts Between 200 keV and 1 MeV

The Energy Spectra of Electron Microbursts Between 200 keV and 1 MeV

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