The effective recombination coefficient measured in the auroral E-region during a sudden commencement electron precipitation event

Abstract. Relativistic electron dropout (RED) events are characterized by fast electron flux decrease at the geostationary orbit. It is known that the main loss process is non adiabatic and more effective for the high energy particles. RED events generally start to occur at midnight sector and propagate to noon sector and are correlated with magnetic field stretching. In this paper, we discuss this kind of event can be caused from pitch angle diffusion induced when the gyro radius of the electrons is comparable to the radius of curvature of the magnetic field and the magnetic moment is not conserved any more. While this process has been studied theoretically, the question is whether electron precipitation could be explained with this process for the real field configuration. This paper will show that this process can successfully explain the precipitation that occurred on 14 June 2004 observed by the low-altitude (680 km) polar orbiting Korean satellite, STSAT-1. In this precipitation event, the energy dispersion showed higher energy electron precipitation occurred at lower L values. This feature is a good indicator that precipitation was caused by the magnetic moment scattering in the geomagnetic tail. This interpretation is supported by the geosynchronous satellite GOES observations that showed significant magnetic field distortion occurred on the night side accompanying the electron flux depletion. Tsyganenko-01 model also shows the magnetic moment scattering could occur under the geomagnetic conditions existing at that time. We suggest the pitch angle scattering by field curvature violating the first adiabatic invariant as a possible candidate for loss mechanism of relativistic electrons in radiation belt.

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Auroral ionospheric E region parameters obtained from satellite-based far ultraviolet and ground-based ionosonde observations: Effects of proton precipitation

10.5194/angeo-2019-110 ◽

2019 ◽

Author(s):

Harold K. Knight

Keyword(s):

Remote Sensing ◽

Optical Emission ◽

Electron Precipitation ◽

E Region ◽

Emission Models ◽

Proton Precipitation ◽

Far Ultraviolet ◽

Proton Aurora ◽

Remote Sensing Methods

Abstract. Coincident auroral far ultraviolet (FUV) and ground-based ionosonde observations are compared for the purpose of determining whether auroral FUV remote sensing algorithms that assume pure electron precipitation are biased in the presence of proton precipitation. Auroral particle transport and optical emission models, such as the Boltzmann 3-Constituent (B3C) model, predict that maximum E region electron density (NmE) values derived from auroral Lyman-Birge-Hopfield (LBH) emission assuming electron precipitation will be biased high by up to ~ 20 % for pure proton aurora, while comparisons between LBH radiances and radiances derived from in situ particle flux observations (i.e., Knight et al., 2008, 2012) indicate that the bias associated with proton aurora should be much larger. Surprisingly, in the comparisons with ionosonde observations described here, no bias associated with proton aurora is found in FUV-derived auroral NmE, which means that auroral FUV remote sensing methods for NmE are more accurate in the presence of proton precipitation than was suggested in the aforementioned earlier works. Possible explanations for the discrepancy with the earlier results are discussed.

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Satellite and ground-based observations of a large-scale electron precipitation event

2011 XXXth URSI General Assembly and Scientific Symposium ◽

10.1109/ursigass.2011.6051151 ◽

2011 ◽

Author(s):

Rory J. Gamble ◽

Craig J. Rodger ◽

Mark A. Clilverd ◽

Neil R. Thomson ◽

Thomas Ulich ◽

...

Keyword(s):

Large Scale ◽

Electron Precipitation ◽

Precipitation Event

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An auroral-zone electron precipitation event and its relationship to a magnetic bay

Journal of Geophysical Research Atmospheres ◽

10.1029/jz067i004p01357 ◽

1962 ◽

Vol 67 (4) ◽

pp. 1357-1366 ◽

Cited By ~ 33

Author(s):

R. R. Brown ◽

W. H. Campbell

Keyword(s):

Auroral Zone ◽

Electron Precipitation ◽

Precipitation Event

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A consideration of the effective recombination coefficient in the E-region of the ionosphere

Journal of Atmospheric and Terrestrial Physics ◽

10.1016/0021-9169(68)90120-7 ◽

1968 ◽

Vol 30 (3) ◽

pp. 473-478 ◽

Cited By ~ 8

Author(s):

T. Yonezawa

Keyword(s):

Recombination Coefficient ◽

E Region

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Quasi-periodic precipitation with periods between 40 and 60 minutes

Annales Geophysicae ◽

10.1007/s00585-996-0707-1 ◽

1996 ◽

Vol 14 (7) ◽

pp. 707-715 ◽

Cited By ~ 15

Author(s):

K. Rinnert

Keyword(s):

Electric Field ◽

Electron Density ◽

Electron Precipitation ◽

Statistical Characteristics ◽

Geomagnetic Disturbances ◽

Maximum Probability ◽

Dst Index ◽

Incoherent Scatter ◽

Magnetospheric Tail ◽

E Region

Abstract. Intervals of periodic enhancements of E-region electron density have been found in EISCAT (European Incoherent SCATter) data. The periods are typically between 40 and 60 min. The phenomenon is observed during relatively quiet times, though after geomagnetic disturbances; it may last up to 6 h. The events can occur at all times of day with a maximum probability in the MLT morning sector. Using the EISCAT database from recent years, the statistical characteristics of these events, and their relation to magnetospheric conditions defined by the Dst index and the d.c. electric field perpendicular to B\\= have been derived. The latitudinal extent is found to be several degrees, but the longitudinal extent is not known. It is concluded that these events are due to the periodically modulated flux of electron precipitation controlled by oscillations in the magnetospheric tail.

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