Statistical studies of an effective sunspot number

Two decades ago, the U.S. Air Force Air Weather Service space forecasting group began generating what was termed an effective sunspot number (SSNe) by fitting a model of the critical frequency of the F2 layer (ƒoF2) to observedƒoF2 values. Initially a preprocessing step in a larger analysis package,...

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Bibliographic Details
Published in:Radio science 1997-07, Vol.32 (4), p.1717-1724
Main Authors: Secan, J. A., Wilkinson, P. J.
Format: Article
Language:English
Subjects:
Climatology
Mathematical models
Military aircraft
Packages
Preprocessing
Specifications
Sunspots
Weather
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Summary:Two decades ago, the U.S. Air Force Air Weather Service space forecasting group began generating what was termed an effective sunspot number (SSNe) by fitting a model of the critical frequency of the F2 layer (ƒoF2) to observedƒoF2 values. Initially a preprocessing step in a larger analysis package, this parameter has taken on a life of its own and is now used in various applications for both forecasts and specification of the globalƒoF2 field. This paper describes the various ways in which this parameter is calculated, investigates the behavior of this parameter over solar cycle 21 (1976 through 1986), and compares it with other solar‐ionospheric indices, including R12, IF2, IG, and the Ionospheric Prediction Service (IPS) T index.
ISSN:0048-6604
1944-799X
DOI:10.1029/97RS01350