Influence of meso-scale forcing on the ionosphere-thermosphere system: GITM simulations

We present a systematical study crossing both data analysis and model simulation to improve the specification of the energy and momentum inputs into the ionosphere-thermosphere (IT) system, especially at meso-scale, and the system response. Our results are organized in two parts, meso-scale forcing from above and from below. First, the meso-scale forcing from magnetosphere including flow burst, electric field variability, meso-scale particle precipitation and field-aligned current (FAC) has been analyzed using both satellite and ground-based measurements. The forcing distributions are then implemented in the Global Ionosphere-Thermosphere Model (GITM) to assess the relative contributions of meso-scale forcing to the ionosphere-thermosphere (I-T) system. Secondly, the acoustic gravity waves (AGWs) trigged by the geographic events, such as hurricane and volcano, propagate from lower atmosphere to I-T and cause disturbances observable for the Global Navigation Satellite Systems (GNSS). GITM with local-grid refinement (GITM-R) has been utilized to simulate ionospheric total electron content (TEC) variations induced by those events and compared with GNSS observations. These high-resolution simulations will strongly enhance our understanding and capability to specify the meso-scale forcing for the I-T system.