On the formation of a sharp layer of metallic constituents at sunrise in the lower thermosphere

Shirke, J. S. ; Sridharan, R. ; Gupta, S. P. ; Danilov, A. D. ; Pokhunkov, A. A. ; Semenov, V. K. ; Varfolomeev, V. A. (1981) On the formation of a sharp layer of metallic constituents at sunrise in the lower thermosphere Proceedings of the Indian Academy of Sciences - Earth and Planetary Sciences, 90 (2). pp. 141-146. ISSN 0253-4126

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Results are presented of two instrumented rocket experiments performed from an equatorial station, one at night and the other shortly after sunrise. The ion neutral composition as well as electron density and the amplitude of plasma irregularities were monitored. During the latter flight, a sharp layer of ionisation with its lower boundary at 100 km was observed. The layer had a half width close to 1 km and a peak electron density of 5.6 X 104cm-3. Large amplitude of plasma irregularities, noticed on the negative gradient portion of the layer indicates a downward direction of the polarisation electric field during the observations. The resulting downward drift of photoions as they are produced at sunrise followed by the local decrease of the drift is suggested to be the cause of the layer formation at that altitude. The long lasting nature of such layers once identified on ionograms indicates that they are constituted of metallic ions possibly of micrometeoritic origin deposited overnight in the lower thermosphere. The required photoionisation rate of production of the metallic ions at sunris eis about 2 cm-3 sec-1.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Ionospheric Layer; Photoionisation of Metals; Micrometeoritic Flux; Metallic Layer; Thermosphere
ID Code:89672
Deposited On:30 Apr 2012 14:59
Last Modified:19 May 2016 04:09

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