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| Titel |
Observation of electron biteout regions below sporadic E layers at polar latitudes |
| VerfasserIn |
G. A. Lehmacher, M. F. Larsen, C. L. Croskey |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 33, no. 3 ; Nr. 33, no. 3 (2015-03-20), S.371-380 |
| Datensatznummer |
250121180
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| Publikation (Nr.) |
 copernicus.org/angeo-33-371-2015.pdf |
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| Zusammenfassung |
| The descent of a narrow sporadic E layer near 95 km altitude over Poker
Flat Research Range in Alaska was observed with electron probes on two
consecutive sounding rockets and with incoherent scatter radar during a 2 h period near magnetic midnight. A series of four trimethyl aluminum
chemical releases demonstrated that the Es layer remained just slightly
above the zonal wind node, which was slowly descending due to propagating
long-period gravity waves. The location of the layer is consistent with the
equilibrium position due to combined action of the wind shear and electric
fields. Although the horizontal electric field could not be measured
directly, we estimate that it was ~ 2 mV m−1 southward, consistent with
modeling the vertical ion drift, and compatible with extremely quiet
conditions. Both electron probes observed deep biteout regions just below the
Es enhancements, which also descended with the sporadic layers. We discuss
several possibilities for the cause of these depletions; one possibility is
the presence of negatively charged, nanometer-sized mesospheric smoke
particles. Such particles have recently been detected in the upper
mesosphere, but not yet in immediate connection with sporadic E. Our
observations of electron depletions suggest a new process associated with
sporadic E. |
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