A local ionospheric model for forecasting the critical frequency of the F2 layer during disturbed geomagnetic and ionospheric conditions

• Main Authors: M. Pietrella, L. Perrone
• Format: Article
• Language: English
• Published: Copernicus Publications 2008-02-01
• Series: Annales Geophysicae
• Online Access: https://www.ann-geophys.net/26/323/2008/angeo-26-323-2008.pdf

An ionospheric forecasting empirical local model over Rome (IFELMOR) has been developed to predict the state of the critical frequency of the F2 layer (<I>fo</I>F2) during geomagnetic storms and disturbed ionospheric conditions. Hourly measurements of <I>fo</I>F2 obtained at the Rome observatory, hourly quiet-time values of <I>fo</I>F2 (<I>fo</I>F2_<I>QT</I>), and the hourly time-weighted accumulation series derived from the geomagnetic planetary index <I>a_p</I> (<I>a_p</I>(τ)), were considered during the period January 1976&ndash;December 2003. Under the assumption that the ionospheric disturbance index log(<I>fo</I>F2/<I>fo</I>F2_<I>QT</I>) is correlated to the integrated geomagnetic index <I>a_p</I>(τ), statistically significant regression coefficients are obtained for different months and for different ranges of <I>a_p</I>(τ) and used as input to calculate the short-term ionospheric forecasting of <I>fo</I>F2. 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 <I>fo</I>F2_<I>QT</I> values, were made for significant geomagnetic storm events (<I>a_p</I>&gt;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.