 |
| Titel |
E-layer dominated ionosphere observed by EISCAT/ESR radars during solar minimum |
| VerfasserIn |
Hongtao Cai, Fei Li, Ge Shen, Weijia Zhan, Kangjun Zhou, Ian W. McCrea, Shuying Ma |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087375
|
| Publikation (Nr.) |
 EGU/EGU2014-1411.pdf |
|
|
|
|
|
| Zusammenfassung |
| E-layer dominated ionosphere (ELDI) is referred to vertical profiles having peak density at
E-layer altitudes (Mayer and Jakowski, 2009). In this paper, characteristics of ELDI were
investigated with the help of field-aligned measurements of EISCAT/ESR radars during
2009-2011. ELDI events were identified with simple but reasonable criterions, in which a
minimal duration was required to exclude possible “fake” events induced by random errors in
measurements. It was found that ELDI were observed more often in winter than other
seasons. In winter, occurrence of ELDI peaks around mid-night at auroral latitude,
while it reaches its maximum around geomagnetic local noon at ESR latitude. Our
results imply that ELDI looks like a sporadic rather than a regular phenomenon,
being contrary to previous results inferred from radio occultation measurements.
Discrepancy in duration of ELDI events observed by the two radars is remarkable, being
30 minutes at TromsØ on average and about a half of it at Svalbard. During the
presence of ELDI, average thickness of E-layer exhibits undetectable variations at
the two sites, as well as HmE and the ratio of NmE/NmF. Case studies reveal that
either extra E-layer ionization possible induced by auroral precipitation or density
depletion in F-layer caused by plasma convection alone could lead to the presence
of ELDI. We suggest that both them play an important role in ELDI formation. |
|
|
|
|
|
|