CEDAR/GEM Postdoc: Fully Electrodynamic 3D Time-Domain Model of Lightning-Ionosphere Interactions

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The investigators will develop a full 3-dimensional time-domain model of the lightning-ionosphere interaction, including nonlinear effects and propagation into the magnetosphere. The model will enable accurate measurements of the effects of lightning on the lower ionosphere (70-110 km), in terms of electron density depletions and enhancements, as well as estimates of the fractional energy transmitted through the ionosphere into the magnetosphere. The model calculations can be calibrated against parameters such as the background ionospheric density, lightning peak current and duration, time of day, and type of lightning (cloud-to-ground versus in-cloud). Using this information, a global estimate of the density enhancement due to lightning can be made from existing satellite and ground-based worldwide lightning data. Comparison with analytical models and experimental data will also be made. The coupling of lightning energy to the ionosphere and magnetosphere has remained an unsolved problem for decades. The study will quantify the coupling process through both electrostatic and electromagnetic energy, both on a per-stroke basis and on a global basis, through comparison with worldwide lightning distribution statistics. The model results will provide calibration of lightning energy to the ionosphere and magnetosphere as a function of lightning peak current, duration, geographic location, time of day, and ionospheric conditions. This study will contribute greatly to understanding of the energy coupling between the lower atmosphere and the D-region ionosphere due to lightning, as well as coupling of energy into the inner magnetosphere. Lightning-generated whistler-mode waves are responsible for precipitation of energetic particles from the radiation belts, in the form of Lightning-induced Electron Precipitation (LEP) events.The model will be instrumental in support of the upcoming ASIM (European Space Agency) and TARANIS (CNES, France) satellite missions, which will monitor TLE activity globally beginning in 2012. The model will be disseminated to interested users and will readily run on a reasonable desktop computer; as such, scientists studying TLEs can determine the electric field intensities and ionospheric disturbances associated with their optical observations. The same comparisons will be enabled with ground-based observations of Transient Luminous Events.