Realtime Monitoring of Traveling Ionospheric Disturbances Caused by Tsunamis
Abstract:The ocean-ionosphere coupling associated with tsunamis was predicted as early as the 1970s and had been observed previously by various radio frequency techniques, including arrays of ground-based Global Positioning System (GPS) receivers. Much work is still needed in order to fully understand the coupling mechanism and allow for the development of effective tsunami detection/warning systems. These challenges include the need for additional observations of the tsunami ionospheric signature to provide new scientific insight into the geophysical source phenomenology and wave propagation physics, and to better constrain the conditions under which ocean-atmospheric coupling is effective.
One of the ionospheric signatures of tsunamis is a Traveling Ionospheric Disturbance (TID). ASTRA has developed a realtime TID Mapping System based on HF radio sounding. We will provide examples of TIDs associated with various tsunamis, including the propagation characteristics of the TIDs.
We are deploying an expanded ground-based observation network using strategically placed optical imaging systems together with ASTRA’s TID Mapping Systems, to obtain new information about the ionospheric waves associated with tsunamis. We will also use a published and validated gravity wave ray trace model to perform studies of the propagation of tsunami-generated gravity waves through the atmosphere and into the thermosphere/ionosphere system. This work will also enhance our understanding of upward coupling caused by all gravity wave sources in the lower atmosphere (not just tsunamis) and how this coupling can generate ionospheric irregularities that affect navigation, communications and surveillance systems.