Ionospheric impacts from Tonga eruption - A nested grid TIEGCM study

The ionosphere-thermosphere system embraces a series of large-to-small scale neutral and electro-dynamic processes, but most of them are poorly represented in global numerical models. Limited by the coverage of external inputs and the capability of current computing resources, simply globally sub-dividing the original grids into smaller grids is not an efficient way of studying the physical processes within the interested region. Here we develop an extension to the thermosphere-ionosphere-electrodynamics general circulation model (TIEGCM) to allow for nested grid capability in which we can pose a finer regional grid upon a coarse global grid to study the localized processes. The neutral and electro-dynamics are self-consistently resolved in the nested grid domain. The fields in the nested grid domain communicate with the global domain by time-dependent boundary conditions. The nested grid model is fully parallel in order to make the best use of large-scale parallel computing. We apply this TIEGCM nested grid model to study the ionospheric impacts during the Tonga volcano eruption that happened on January 15, 2022. Our simulation results will be compared with the total electron content measurements from the global navigation satellite system.