Non-trough <i>fo</i>F2 enhancements at near-equatorial dip latitudes
Fine resolution series from three equatorial ionosondes of the IEEY network in West Africa have revealed small-scale daytime peak F2 structures, superposed on the slowly varying minimum or "trough" distribution in the ±5° magnetic latitude zone. We report this new morphology, concentra...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
1998-06-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/16/711/1998/angeo-16-711-1998.pdf |
| Summary: | Fine resolution series from three equatorial
ionosondes of the IEEY network in West Africa have revealed small-scale daytime
peak F2 structures, superposed on the slowly varying minimum or
"trough" distribution in the ±5° magnetic latitude zone. We report
this new morphology, concentrating on <i>f</i>oF2 enhancements of two types:
near-equatorial crests (which travel either northwards or southwards) and
magnetic field-aligned domes, whose onsets last only tens of minutes. Both types
are observed to start at mid-morning or early afternoon hours. We relate their
occurrence with the available variations of <b>Vz</b>=<b>E </b>×<b> B</b>
upward drift which feeds the equatorial plasma fountain. We suggest the <i>f</i>oF2
enhancements to be triggered by brief slow-downs of the <b>Vz</b> velocity near
F2 peak altitude in our West African sector. Their short latitude extent
differentiates them from the larger-scale tropical crest system. Further
analysis of these features should lead to weather-like models of the low
latitude ionosphere variations, where unstable local coupling between processes
seems to be the trigger.<br><br><b>Key words. </b>Ionosphere (Equatorial ionosphere ·
Ionosphere-atmosphere interaction · Plasma temperature and density)</p> |
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| ISSN: | 0992-7689 1432-0576 |