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DC Field | Value | Language |
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dc.contributor.author | Sastri, J. H | - |
dc.date.accessioned | 2008-09-06T11:23:32Z | - |
dc.date.available | 2008-09-06T11:23:32Z | - |
dc.date.issued | 1999-08 | - |
dc.identifier.citation | Annales Geophysicae, Vol. 17, No. 8, pp. 1111 - 1115 | en |
dc.identifier.issn | 0992-7689 | - |
dc.identifier.uri | http://hdl.handle.net/2248/3420 | - |
dc.description.abstract | At dip equatorial stations in the Indian zone, spread-F conditions are known to develop preferentially around midnight during the June solstice (northern summer) months of low solar activity, in association with a distinct increase in F layer height. It is currently held that this onset of spread-F far away from the sunset terminator is due to the generalised Rayleigh-Taylor instability mechanism, with the gravitational and cross-field instability factors (and hence F layer height) playing important roles. We have studied the quarter-hourly ionograms of Kodaikanal (10.2°N; 77.5°E; dip 4°N) for the northern summer months (May-August) of 1994 and 1995 to ascertain the ambient ionospheric conditions against which the post-midnight onset of spread-F takes place. A data sample of 38 nights with midnight onset of spread-F and 34 nights without spread-F is used for the purpose. It is found that a conspicious increase in F layer height beginning around 2100 LT occurs on nights with spread-F as well as without spread-F. This feature is seen in the nocturnal pattern of F layer height on many individual nights as well as of average F layer height for the two categories of nights. The result strongly suggests that the F layer height does not play a pivotal role in the midnight onset of spread-F during the June solstice of solar minimum. The implications of this finding are discussed. | en |
dc.language.iso | en | en |
dc.publisher | European Geosciences Union | en |
dc.relation.uri | http://adsabs.harvard.edu/abs/1999AnGeo..17.1111S | en |
dc.relation.uri | http://www.ann-geophys.net/17/1111/1999/angeo-17-1111-1999.html | en |
dc.subject | Ionosphere (equatorial ionosphere; ionospheric irregularities) | en |
dc.title | Post-midnight onset of spread-F at Kodaikanal during the June solstice of solar minimum | en |
dc.type | Article | en |
Appears in Collections: | IIAP Publications |
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File | Description | Size | Format | |
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Post-midnight onset of spread-F at Kodaikanal during the June solstice of solar minimum | 123.9 kB | Adobe PDF | ![]() View/Open |
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