Computationally Efficient FDTD Calculation of Geoelectric Fields over Complex Conductivity Structures: Time-Dependent TE & TM mode Comparison
Abstract
A notable deficiency in the current SW forecasting chain is the propagation of geoelectric fields from ionosphere to ground using Biot-Savart integrals, which ignore the localized complexity of lithospheric electrical conductivity and the relatively high conductivity of ocean water compared to the lithosphere. Three-dimensional models of Earth conductivity with mesoscale spatial resolution are being developed, but a new approach is needed to incorporate this information into the SW forecast chain. We present results from a parametric study of the effect of idealized earth conductivity structures on time-dependent geoelectric field behavior for TE (Efield strike parallel) and TM (Efield strike perpendicular) modes. Our parametric study exploits a new Finite Difference Time Domain (FDTD) model, called LANL GeoRad, that utilizes novel space-time rescalings to remove the microsecond time-step limitations of traditional FDTD. Inductive effects, associated with currents flowing along the edge of conductive discontinuities, are highlighted and implications for the impedance tensor measured at the surface are discussed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMIN33D0886J
- Keywords:
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- 4313 Extreme events;
- NATURAL HAZARDSDE: 7904 Geomagnetically induced currents;
- SPACE WEATHERDE: 7934 Impacts on technological systems;
- SPACE WEATHERDE: 7999 General or miscellaneous;
- SPACE WEATHER