Robust uncertainty quantification of the volume of tsunami ionospheric holes for the 2011 Tohoku-Oki earthquake: towards low-cost satellite-based tsunami warning systems

We develop a new method to analyze the total electron content (TEC) depression in the ionosphere after a tsunami occurrence. We employ Gaussian process regression to accurately estimate the TEC disturbance every 30 s using satellite observations from the global navigation satellite system (GNSS) network, even over regions without measurements. We face multiple challenges. First, the impact of the acoustic wave generated by a tsunami onto TEC levels is nonlinear and anisotropic. Second, observation points are moving. Third, the measured data are not uniformly distributed in the targeting range. Nevertheless, our method always computes the electron density depression volumes, along with estimated uncertainties, when applied to the 2011 Tohoku-Oki earthquake, even with random selections of only 5 % of the 1000 GPS Earth Observation Network System receivers considered here over Japan. Also, the statistically estimated TEC depression area mostly overlaps the range of the initial tsunami, which indicates that our method can potentially be used to estimate the initial tsunami. The method can warn of a tsunami event within 15 min of the earthquake, at high levels of confidence, even with a sparse receiver network. Hence, it is potentially applicable worldwide using the existing GNSS network

Computation of Redox Potential of Molecule by Energy Representation Method

We have been applied the conventional approach based on the molecular dynamics simulation to estimate the redox potential so far. In this study, we have focused the computational conditions in order to estimate standard redox potential by using the energy representation method: we calculate excess chemical potential increasing the number of solvent molecules and sampling data for the preparation of energy distribution functions. From these results, we have found that the computational value of the standard redox potential is close to the experimental value in the case of the system with larger number of solvent molecules unaffected by the behavior of counter-ion when we take a sufficient sampling data for the energy distribution functions.Selected Papers from the International Symposium on Computational Science - International Symposium on Computational Science Kanazawa University, Japa

Structure and hydration free energy of ketone compound in neutral and cationic state by molecular dynamics simulation

Structure and hydration property of acetone and 3-pentaone in the neutral and cationic state were investigated by using molecular dynamics (MD) and free energy calculations. The force field parameters of stretching vibration, angle bending, and partial charges of each molecule in the neutral and cationic state were developed by using density functional theory (DFT) calculations with B3LYP method and 6-31+G** basis set. The optimized structures by using these force field parameters in gas phase were compared with the experimental data and AMBER force fields parameters (parm99). From the results, the optimized structure in the neutral state of acetone was in good agreement with the experimental data. The evaluated hydration free energy in the neutral state of acetone was closed to the experimental data, while that of 3-pentaone was little bit larger than the experimental data. The ionization effect of ketone molecule on the hydration free energies was found to be significant in both molecules