Density enhancements associated with equatorial spread <I>F</I>
Forces governing the three-dimensional structure of equatorial spread-<I>F</I> (ESF) plumes are examined using the NRL SAMI3/ESF three-dimensional simulation code. As is the case with the equatorial ionization anomaly (IA), density crests within the plume occur where gravitational an...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2010-02-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/28/327/2010/angeo-28-327-2010.pdf |
| Summary: | Forces governing the three-dimensional structure of equatorial spread-<I>F</I>
(ESF) plumes are examined using the NRL SAMI3/ESF three-dimensional
simulation code. As is the case with the equatorial ionization anomaly (IA),
density crests within the plume occur where gravitational and diffusive
forces are in balance. Large <I><B>E</B></I>×<I><B>B</B></I> drifts
within the ESF plume place these crests on field lines with apex heights
higher than those of the
background IA crests. Large poleward field-aligned ion velocities within
the plume result in large ion-neutral diffusive forces that support these
ionization crests at altitudes higher than background IA crest altitudes.
We show examples in which density enhancements associated with ESF, also
called "plasma blobs," can occur within an ESF plume on density-crest field
lines, at or above the density crests. Simulated ESF density enhancements
reproduce all key features of those that have been observed in situ. |
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| ISSN: | 0992-7689 1432-0576 |