Impact of different AGWs on the Ionospheric Disturbances Generated by the 2022 Tonga Eruption: Comparison of GITM-R simulations with GNSS observations

Volcanic eruptions provide broad spectral forcing to the atmosphere and can create disturbances in the ionosphere-thermosphere (IT) system by propagation of the associated acoustic-gravity waves (AGWs). These disturbances can be observed by Global Navigation Satellite Systems (GNSS) and used to analyze various properties of the initial perturbation such as localization [1] and total energy content [2]. The focus of this study is to simulate ionospheric Total Electron Content (TEC) variations induced by 2022 Hunga Tonga-Hunga Ha’apai (HTHH) event for comparison to GNSS data. Simulations are performed using the Global Ionosphere-Thermosphere Model with local mesh Refinement (GITM-R) driven by inputs providing different aspects of the atmosphere’s AGW response [3]. Simulation results from the High Altitude Mechanistic General Circulation Model (HIAMCM) are used to excite Traveling Ionospheric Disturbances (TIDs) related to secondary gravity waves [4] and results from the Whole Atmosphere Community Climate Model with IT extension (WACCM-X) are used to excite TIDs generated by surface guided modes such as Lamb and Perkins waves [5]. Additionally, near the source, acoustic waves are driven by a simplified acoustic source representation [6]. Different specifications at GITM-R’s lower boundary are performed to compare IT disturbances induced by the different primary AGW propagation mechanisms.