The last decade demonstrated that seismic waves and tsunamis are coupled to the ionosphere. Observations of Total Electron Content (TEC) and airglow perturbations of unique quality and amplitude were made during the Tohoku, 2011 giant Japan quake. Observations of much lower tsunamis down to a few cm in sea uplift are now routinely done. A comprehensive science of the coupling of ocean to space must therefore integrate oceanic and ground seismic sources, which are important and strong ionospheric drivers from below.
These telluric ionospheric signals are important for improving the tsunami warning strategy, especially for tsunamis occurring in areas not covered by ground warning systems or generated by non-seismic sources in the open ocean (i.e. air or sea explosions, landslides, impacts). Ionospheric detection of seismic events and tsunamis are also unique to understand the coupling between the lower atmosphere and ionosphere: in several cases, data of the driver from below (i.e. ground displacement) and of the ionospheric impact (i.e. ionospheric perturbations) can be recorded. We can therefore expect to better constrain, through travel time and waveform inversion, the various parameters (atmospheric viscosity, collision frequencies) controlling the coupling between the lower atmosphere and the ionosphere.
This 4 years project, funded by US ONR is focused toward three major goals, both related to inversions. The two first goals are to demonstrate that a tsunami oceanic uplift can be retrieved from the ionospheric data and to complete through collaboration between IPGP, Univ. Illinois and CEA the installation of a new airglow observing system in the Pacific, in Tahiti Island. The last one will be to demonstrate that the coupling physics and coupling parameters can be inverted from the joint data set of surface drivers (e.g., tsunami or seismic signals) and ionospheric perturbations.
For more information: Ocean2space