TY - JOUR
T1 - Solar cycle effects on parallel electric field acceleration of auroral electron beams
AU - Cattell, C.
AU - Dombeck, J.
AU - Hanson, L.
PY - 2013/9
Y1 - 2013/9
N2 - We present the occurrence frequency of downgoing auroral electron beams in magnetic local time and invariant latitude, and the dependence on solar cycle, as indicated by F10.7, on whether the ionospheric foot point of the satellite is illuminated or dark, and on the energy flux carried by the electrons. As previously reported, we find that the occurrence of electron beams peaks in the premidnight local time sector and that solar illumination at the foot point (solar zenith angle) reduces both the occurrence and energy of the electron beams. The effect of solar maximum conditions (indicated by F10.7) is almost as large as the effect of the solar zenith angle. The characteristic energy of the electron beams is dependent on the energy flux carried, in addition to both solar zenith angle and F10.7. The beam energy (and therefore the parallel potential drop) is ~1.6 times higher for during solar minimum than during solar maximum for both dark and illuminated foot points. The beam energy during dark solar minimum conditions is a factor of ~3 more than during sunlit minimum conditions. The "area" covered by intense aurora is also reduced during solar maximum, for both sunlit and dark conditions. There is no evidence that the statistical results are due to the fact that acceleration via parallel electric fields moves to lower latitudes during solar maximum. Key Points Intense auroral electrons suppressed by high F10.7 both for dark and sunlightBeam energy depends on illumination, solar cycle, and energy flux carriedEnergy is 1.6 times higher during solar minimum than maximum for dark and sunlight
AB - We present the occurrence frequency of downgoing auroral electron beams in magnetic local time and invariant latitude, and the dependence on solar cycle, as indicated by F10.7, on whether the ionospheric foot point of the satellite is illuminated or dark, and on the energy flux carried by the electrons. As previously reported, we find that the occurrence of electron beams peaks in the premidnight local time sector and that solar illumination at the foot point (solar zenith angle) reduces both the occurrence and energy of the electron beams. The effect of solar maximum conditions (indicated by F10.7) is almost as large as the effect of the solar zenith angle. The characteristic energy of the electron beams is dependent on the energy flux carried, in addition to both solar zenith angle and F10.7. The beam energy (and therefore the parallel potential drop) is ~1.6 times higher for during solar minimum than during solar maximum for both dark and illuminated foot points. The beam energy during dark solar minimum conditions is a factor of ~3 more than during sunlit minimum conditions. The "area" covered by intense aurora is also reduced during solar maximum, for both sunlit and dark conditions. There is no evidence that the statistical results are due to the fact that acceleration via parallel electric fields moves to lower latitudes during solar maximum. Key Points Intense auroral electrons suppressed by high F10.7 both for dark and sunlightBeam energy depends on illumination, solar cycle, and energy flux carriedEnergy is 1.6 times higher during solar minimum than maximum for dark and sunlight
KW - auroral acceleration
KW - electron beams
KW - solar cycle
KW - solar illumination
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U2 - 10.1002/jgra.50546
DO - 10.1002/jgra.50546
M3 - Article
AN - SCOPUS:84889057144
SN - 2169-9380
VL - 118
SP - 5673
EP - 5680
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 9
ER -