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| Titel |
Effects of solar eclipse on the electrodynamical processes of the equatorial ionosphere: a case study during 11 August 1999 dusk time total solar eclipse over India |
| VerfasserIn |
R. Sridharan, C. V. Devasia, N. Jyoti, Diwakar Tiwari, K. S. Viswanathan, K. S. V. Subbarao |
| 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 ; 20, no. 12 ; Nr. 20, no. 12, S.1977-1985 |
| Datensatznummer |
250014512
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| Publikation (Nr.) |
 copernicus.org/angeo-20-1977-2002.pdf |
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| Zusammenfassung |
The effects on the
electrodynamics of the equatorial E- and F-regions of the ionosphere, due to
the occurrence of the solar eclipse during sunset hours on 11 August 1999, were
investigated in a unique observational campaign involving ground based
ionosondes, VHF and HF radars from the equatorial location of Trivandrum (8.5°
N; 77° E; dip lat. 0.5° N), India. The study revealed the nature of changes
brought about by the eclipse in the evening time E- and F-regions in terms of (i)
the sudden intensification of a weak blanketing ES-layer and
the associated large enhancement of the VHF backscattered returns, (ii)
significant increase in h' F immediately following the eclipse and (iii)
distinctly different spatial and temporal structures in the spread-F
irregularity drift velocities as observed by the HF radar. The significantly
large enhancement of the backscattered returns from the E-region coincident
with the onset of the eclipse is attributed to the generation of steep electron
density gradients associated with the blanketing ES ,
possibly triggered by the eclipse phenomena. The increase in F-region base
height immediately after the eclipse is explained as due to the reduction in
the conductivity of the conjugate E-region in the path of totality connected to
the F-region over the equator along the magnetic field lines, and this, with
the peculiar local and regional conditions, seems to have reduced the E-region
loading of the F-region dynamo, resulting in a larger post sunset F-region
height (h' F) rise. These aspects of E-and F-region behaviour on the eclipse
day are discussed in relation to those observed on the control day.
Key words. Ionosphere (electric
fields and currents; equatorial ionosphere; ionospheric irregularities) |
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