 |
| Titel |
Global transport and localized layering of metallic ions in the upper atmospherer |
| VerfasserIn |
L. N. Carter, J. M. Forbes |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 17, no. 2 ; Nr. 17, no. 2, S.190-209 |
| Datensatznummer |
250013672
|
| Publikation (Nr.) |
 copernicus.org/angeo-17-190-1999.pdf |
|
|
|
|
|
| Zusammenfassung |
A numerical model has been developed which
is capable of simulating all phases of the life cycle of
metallic ions, and results are described and interpreted
herein for the typical case of Fe+ ions. This cycle begins
with the initial deposition of metallics through meteor
ablation and sputtering, followed by conversion of
neutral Fe atoms to ions through photoionization and
charge exchange with ambient ions. Global transport
arising from daytime electric fields and poleward/
downward di.usion along geomagnetic field lines,
localized transport and layer formation through de-
scending convergent nulls in the thermospheric wind
field, and finally annihilation by chemical neutralization
and compound formation are treated. The model thus
sheds new light on the interdependencies of the physical
and chemical processes a.ecting atmospheric metallics.
Model output analysis confirms the dominant role of
both global and local transport to the ion's life cycle,
showing that upward forcing from the equatorial electric
field is critical to global movement, and that diurnal and
semidiurnal tidal winds are responsible for the forma-
tion of dense ion layers in the 90±250 km height region.
It is demonstrated that the assumed combination of
sources, chemical sinks, and transport mechanisms
actually produces F-region densities and E-region layer
densities similar to those observed. The model also
shows that zonal and meridional winds and electric
fields each play distinct roles in local transport, whereas
the ion distribution is relatively insensitive to reasonable
variations in meteoric deposition and chemical reaction
rates.
Key words. Ionosphere (ion chemistry and
composition; ionosphere-atmosphere interactions). |
| |
|
| Teil von |
|
|
|
|
|
|
|
|