HR: 17:35h
AN: A24B-06    [Abstracts]
TI: Bottom Topography Correction by Assimilation of Tsunami Simulation Model and Tide Gauge Data With Particle Filter
AU: * Nakamura, K
EM: nakakazu@ism.ac.jp
AF: The Institute of Statistical Mathematics, JST CREST, 4-6-7 Minami-Azabu, Minato-ku, Tokyo, 1068569, Japan
AU: Hirose, N
EM: hirose@riam.kyushu-u.ac.jp
AF: Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-kouen, Kasuga, Fukuoka, 8168560, Japan
AU: Higuchi, T
EM: higuchi@ism.ac.jp
AF: The Institute of Statistical Mathematics, JST CREST, 4-6-7 Minami-Azabu, Minato-ku, Tokyo, 1068569, Japan
AB: We demonstrate the results of applying the sequential data assimilation (SDA) to a tsunami simulation model. A shallow water equations model and tide gauge data are employed in DA. Most of our concerns in DA are paid to validate information on depths of sea bottom. The reason is that bottom topography data sets are erroneous and depths affect propagation speed of tsunamis, which results in inaccurate tsunami forecasts. Because the depths are included in the simulation model as boundary condition, we can modify the depths by putting them into state vector. Specifically, we allow for an error term in the bottom topography and its statistical inference is carried out through DA. The filtering method used in SDA is the particle filter (PF) due to the computational and statistical reasons. The PF is also an ensemble based assimilation procedure, and then it has a similar algorithmic structure with the ensemble Kalman filter (EnKF). However, there exist some different characteristics between them. In this study, we conducted three types of numerical experiment and analysis: twin experiment of bottom topography correction, bottom topography estimation based on real tide gauge data of Okushiri tsunami in 1993. The result of twin experiment shows the effectiveness of our DA. The result of DA to real data suggests that almost all part of Yamato Rises is shallower than the average of available data sets (four data sets at hand). We also discuss the differences among raw data, bottom topography data sets and obtained depths by DA.
DE: 3315 Data assimilation
DE: 4277 Time series experiments (1872, 3270, 4475)
DE: 4468 Probability distributions, heavy and fat-tailed (3265)
DE: 4564 Tsunamis and storm surges
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly