Sridharan, R. ; Devasia, C. V. ; Jyoti, N. ; Tiwari, Diwakar ; Viswanathan, K. S. ; Subbarao, K. S. V. (2002) 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 Annales Geophysicae, 20 (12). pp. 1977-1985. ISSN 1432-0576
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Official URL: http://www.ann-geophys.net/20/1977/2002/angeo-20-1...
Related URL: http://dx.doi.org/10.5194/angeo-20-1977-2002
Abstract
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.
Item Type: | Article |
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Source: | Copyright of this article belongs to Copernicus Group. |
Keywords: | Ionosphere (Electric Fields and Currents; Equatorial Ionosphere; Ionospheric Irregularities) |
ID Code: | 96056 |
Deposited On: | 04 Dec 2012 11:07 |
Last Modified: | 19 May 2016 08:36 |
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