Relation between daytime and nighttime values of the critical frequency foF2

A. D. Danilov
Institute of Applied Geophysics, Moscow, Russia


[1]  The effect detected earlier by L. B. Vanina and A. D. Danilov (2003) is discussed in detail. The effect is that a high enough and statistically significant negative correlation coefficient is observed between the near-noon and near-midnight values of the critical frequency foF2. In this paper, the peculiarities of the effect (dependence on season, solar and geomagnetic activity, and geomagnetic latitude) are considered in detail on the basis of the data of a few ionospheric stations located in various geographic zones.

Received 6 December 2005; revised 18 May 2006; accepted 17 August 2006; published 28 November 2006.

Keywords: Critical frequency; Day-to-night ratio; Seasonal variation.

Index Terms: 2499 Ionosphere: General or miscellaneous; 2443 Ionosphere: Midlatitude ionosphere; 2427 Ionosphere: Ionosphere/atmosphere interactions.


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