Coupling Tsunamis with the Ionosphere: A New Modeling Approach
Wednesday, 17 December 2014
Tsunamis can generate gravity waves propagating upward through the atmosphere and induce total electron content (TEC) disturbances in the ionosphere. The wave propagation has been captured by waveform models, which are effective but lack physical consistency. For the first time, we have implemented tsunami-generated gravity waves into the Global Ionosphere-Thermosphere Model (GITM) to develop a fully physics-based three-dimensional model describing the upper atmosphere under the influence of tsunamis. The model takes tsunami wave characteristics, including the wave heights, wavelengths and propagation velocities at the ocean surface as input parameters and characterizes the ionosphere-thermosphere between altitudes 100km and 600km. The computational region and grid resolution in the horizontal direction can be specifically adjusted according to applications.
As an initial application and test case, we simulate the ionosphere-thermosphere above the US west coastal region where the tsunamis caused by the 2011 Tokohu earthquake arrived and caused disturbances in the ionosphere. To validate our modeling approach, the GITM-simulated TEC disturbances are compared with GPS-derived TEC measurements at multiple geographic locations. We envision that modeled and measured TEC perturbations could play a critical role in detecting and imaging the upper atmospheric signatures of natural hazards including earthquakes, tsunamis, and volcanic eruptions.