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Ann. Geophys., 26, 323-334, 2008
www.ann-geophys.net/26/323/2008/
© European Geosciences Union 2008
A local ionospheric model for forecasting the critical frequency of the F2 layer during disturbed geomagnetic and ionospheric conditions
M. Pietrella and L. Perrone
Istituto Nazionale di Geofisica e Vulcanologia, via di Vigna Murata 605, 00143 Rome, Italy
Abstract. An ionospheric forecasting empirical local model over Rome (IFELMOR) has
been developed to predict the state of the critical frequency of the F2
layer (foF2) during geomagnetic storms and disturbed ionospheric conditions.
Hourly measurements of foF2 obtained at the Rome observatory, hourly
quiet-time values of foF2 (foF2QT), and the hourly time-weighted
accumulation series derived from the geomagnetic planetary index ap
(ap(τ)), were considered during the period January 1976–December
2003. Under the assumption that the ionospheric disturbance index log(foF2/foF2QT)
is correlated to the integrated geomagnetic index ap(τ),
statistically significant regression coefficients are obtained for different
months and for different ranges of ap(τ) and used as input to
calculate the short-term ionospheric forecasting of foF2. The empirical
storm-time ionospheric correction model (STORM) was used to make comparisons
with the IFELMOR model. A few comparisons between STORM's performance,
IFELMOR's performance, the median measurements and the foF2QT values,
were made for significant geomagnetic storm events (ap>150) occurring
from 2000 to 2003. The results provided by IFELMOR are satisfactory, in
particular, for periods characterized by high geomagnetic activity and very
disturbed ionospheric conditions.
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