Ionoseis: A Package to Model Coseismic Ionospheric Disturbances

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

Over the past few years we have been developing the software package IonoSeis to model coseismic ionospheric disturbances (CIDs) systematically registered with GNSS receivers after shallow earthquakes of magnitude 6.7 and more. IonoSeis combines multiple existing pieces of code into a single package with additional modules. Our integrated approach allows rapid reconstruction of the initial acoustic phase of coseismic total electron content (TEC) perturbations. The code is written in Fortran and uses NetCDF input and output grid files and SAC time-series outputs. The ionosphere background model is derived from the International Reference Ionosphere package IRI2016, and the atmospheric model is derived from the empirical, global reference atmospheric model NRLMSISE-00. Using these two inputs, acoustic-ray tracing is performed in the atmosphere to determine arrival times and geometries of acoustic waves at ionospheric altitudes. The ray tracing is performed using the code WASP3D (Dessa et al., 2005), which operates in a spherical coordinate system, and was previously used for infrasound modeling in a heterogeneous atmosphere. The ray tracing can account for non-stationary atmospheric models and we have integrated the Horizontal Wind Model (HWM) from Drob et al. (2015). Amplitude effects of the propagation are approximated (e.g. viscous attenuation); however, we are able to accurately reconstruct not only arrival times, but also perturbation amplitude and phase. The code supports line-of-sight integration with non-stationary satellites and produces both background ionosphere and perturbation TEC time series. We demonstrate the capabilities of this new package and show how it is currently being utilized for ionospheric studies of earthquakes and tsunamis. Because this modeling is based on ray-tracing, it is fast; we plan to eventually use this package for near-real time modeling and tsunami early warning. During this presentation we will discuss the existing obstacles that currently preclude this type of rapid application.

Presenting Author: Thomas D. Mikesell

Authors