10:00 AM - 10:15 AM
[HDS12-05] Observations of sea surface heights using an airborne radar altimeter for great tsunamis early detection
Keywords:tsunami forecast, airborne observations, radar altimeter, GNSS
We performed nadir pointing observations using Frequency Modulated Continuous Wave (FMCW) radar, which is attached to the bottom of an airplane body. The radar observation procedure is basically similar to the present satellite radar altimeter. However, in airborne observation, airplane altitude is changing by a few meters at any time during the flight. Thus, a precise prediction of airplane positions by Global Navigation Satellite System (GNSS) is also important. We estimated the position and altitude by a baseline kinematic analysis. We then estimated the averaged sea surface height (SSH) by the radar altimeter observation and the GNSS analysis result.
We conducted airborne observations once in June 2016, and twice in December 2016. To check the precision of SSH measurements, the flight days and paths were decided according to the satellite SSH altimeter Jason-2 and Jason-3 schedules. We measured the SSH several times and compared with the Jason results. After correcting the geoid and tidal changes, we confirmed that our observation error is less than 10 cm in average, which is sufficient to capture large tsunamis offshore. In the future, we expect to form a dense observation network by using multiple commercial airplanes equipped with the same radar altimeter, which enables real-time tsunami detections. We also expect that future developments of the radar technology can lead to a low operational and maintenance cost compared to the existing tsunami observing systems.