Model-Based Analysis of Ionospheric Reaction to Regular and Disturbed 27-day Solar EUV Profiles

Kurzfassung

Abstract AGU Fall Meeting Session: SA009 - Dynamics of the Thermosphere and Ionosphere System at Low and Middle Latitudes Driven by External and Internal Forcing Model-based analysis of ionospheric reaction to regular and disturbed 27-day solar EUV profiles Hanna Dühnen1, Rajesh Vaishnav2, Erik Schmölter1, Christoph Jacobi2 1 German Aerospace Center, Deutsches Zentrum für Luft- und Raumfahrt (DLR) Institut für Solar-Terrestrische Physik 2 University Leipzig, Germany, Institute for Meteorology Solar extreme ultraviolet (EUV) variability plays a dominant role in modulating upper atmosphere ionization processes, showing a strong influence on ionospheric composition and key parameters such as electron density and total electron content (TEC) across various temporal scales. The solar rotation causes a regular 27-day EUV pattern which in turn can be observed in the ionospheric composition as well. In addition to these variations, the EUV signature is overlaid by long-term and short-term tends or events which can drive changes within the ionospheric plasma. Therefore, the ionosphere shows complex reactions to EUV variability. Using numerical simulations performed with the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM), the ionospheric response to different 27-day solar rotation periods and the subsequent ionospheric response can be analyzed in high spatial and temporal resolution. The study focuses both on global and local total electron content (TEC) variations, as well as changes in ionospheric constituents, such as O+ and O2+. By use of the OTHITACS (Open Time-Series of the High-Resolution Ionosphere-Thermosphere Aeronomic Climate Simulation), the analysis is performed on multiple years (2000 to 2020) of ionospheric data with different solar activity periods, various EUV profiles and both quiet and storm conditions. Despite irregularities in the EUV profiles, a dominance of the 27-day rotation in the ionospheric plasma is observed, which was also demonstrated in previous studies on the delayed response. However, rotation cycles with disturbed EUV profiles show stronger accumulation processes of specific ionized components (O+ and O2+). This particularly affects the plasma at altitudes of up to 230 km.