A prediction model of foF2 over periods of severe geomagnetic activity

A prediction procedure of the hourly values of the critical frequency of the F2 ionospheric layer, foF2, based on the geomagnetic
index, is presented. The geomagnetic index used in this study is the time-weighted accumulation magnetic index ap(s) based on the recent
past history of the planetary index ap.
The procedure is based on an empirical relationship between the ratio log(NmF2(t)/NmF2M(t)) and ap(s), where NmF2(t) is the hourly
maximum electron density at the F2 peak layer and NmF2M(t) is its ‘quiet’ value. The prediction of foF2 has been calculated during
periods of severe magnetic activity in the current solar cycle 23 using data processed at the Rome ionospheric observatory. The performance
of the model, during negative ionospheric storms, can be considered satisfactory, given that the root mean square (r.m.s.), calculated
between measured and forecasted foF2, ranged between 0.74–2.0 MHz.

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