Tohoku-Oki Tsunami Revisit: Improved Tsunami-Ionosphere Coupling Model WP-GITM

Tsunamis can generate atmospheric gravity waves that propagate upward and induce ionospheric disturbances. The ionospheric responses to the 11 March 2011 Tohoku-Oki tsunami have been reported extensively. To better understand the tsunami-ionospheric coupling processes, previously we developed the Wave Perturbation - Global Ionosphere Thermosphere Model (WP-GITM), a three-dimensional and time-dependent model and applied it to simulate the ionospheric perturbations due to the Tohoku-Oki tsunami arrival at the US west coast. Although the simulated ionospheric total electron content (TEC) perturbations agreed reasonably well with Global Positioning System (GPS) observations, some model-observation discrepancies were found. The discrepancies are partially due to a key assumption of WP-GITM: the neutral atmosphere between 0 and 100km altitudes is isothermal. In reality, the neutral temperature significantly varies with height below 100km altitude. In the present work, we remove the isothermal-atmosphere assumption and adopt a stratified atmosphere approach, in which the neutral atmosphere below 100km altitude is divided into multiple layers with neutral density, temperature and wind profiles specified by empirical models or observations. The improved WP-GITM is expected to better reproduce the ionospheric TEC perturbations caused by the Tohoku-Oki tsunami. Moreover, for this event we conduct a number of WP-GITM simulations to study the sensitivity of TEC perturbations in response to different tsunami wave heights. We also explore the possibility of utilizing the Data Assimilation Research Testbed (DART) to obtain the optimal tsunami wave heights to drive WP-GITM using GPS TEC observations.