Approximating solar activity; implications for ionospheric modelling

Activity: Academic and Industrial eventsConference, workshop or symposium


The F10.7 solar radio flux is one of the most commonly used indices of solar activity (Tapping, 2013) and is essential for the proper planning, operation and management of space weather services. The 81-day average value (F10.7A) is often used to smooth the effects of variation of the solar output (Girazian & Withers, 2015). Two differing methods of calculating F10.7A are commonly used in the literature; the ‘centred’ method, which calculates the mean of the day of interest and the 40 days on either side and the ‘right aligned’ method, which calculates the mean of the day of interest and the prior 80 days. The increasing demand for accurate modelling of the Earth’s upper atmosphere for practical applications requires a consistent choice of the calculation method of F10.7A ¬.
This study highlights the impact of the two methods of calculating F10.7A on output from an ionospheric model, in this case, the Thermosphere Ionosphere Electrodynamics Circulation Model (TIE-GCM) around the two previous solar maxima in 2014 and 2001. Differences in total electron content, hmF2, NmF2 and the O/N2 ratio are presented. These changes vary with location and local time, sometimes they exceed 7 TECu. It is shown that these differences are greater as the F10.7 cm solar radio flux increases. A consistent choice of calculation method for F10.7A will be increasingly important in the next few years around solar maximum.
A number of models including TIE-GCM are designed to use the centred version of F10.7A, this cannot be used in an operational setting, as it requires 40 days of future data. This study investigates alternative options and makes recommendations for such cases.
PeriodApr 2023
Event titleMagnetosphere Ionosphere and Solar-Terrestrial Physics (MIST) meeting
Event typeConference
LocationBirmingham, United KingdomShow on map
Degree of RecognitionNational