Modeling Of The Delayed Ionospheric Response With The TIE-GCM Model

In this study the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) is used to describe the delayed ionospheric response to solar Extreme Ultraviolet (EUV) radiation and its varying relation to solar and geomagnetic activity (e.g. stronger impact of the solar wind during winter season in the northern hemisphere). Long-term changes, at time scales longer than the 27-day solar rotation cycle, are analyzed and the dependence of the ionospheric delay on the solar activity is presented based on calculations at a chosen location in the mid-latitudes. Ionospheric delays of 2, 11 and 20 h can be correlated to the mean solar radio flux index (F10.7) values of 95, 115 and 135 sfu. In addition, a possible relation of the delayed ionospheric response with the geomagnetic activity is analyzed with TIE-GCM model runs, that estimate an ionospheric delay of 15 h for a corresponding Kp-index of≈ 0.91 and an ionospheric delay of 17 h for a corresponding Kp-index of ≈ 2.88 (during December). These differences are related to changes in electron temperature and ion velocity perpendicular to the geomagnetic field lines. The results suggest a significant impact of transport processes on the delayed ionospheric response.