The PI proposes a three-year effort for a theoretical investigation of the nonlinear electrodynamic coupling to the mesosphere and the lower ionosphere of intense short duration electromagnetic pulses originating in lightning discharges. He will develop a three- dimensional model describing the changes in the electron density, chemistry, and optical emissions in the D region stimulated by electromagnetic energy released in tropospheric lightning discharges. Expected results include (1) determination of the 3-D configurations of the disturbed ionospheric regions within which significant changes occur in temperature, airglow, electron density, and chemical processes; (2) determination of the fraction of electromagnetic energy from lightning deposited in the lower ionosphere and the dominant sinks of such energy; (3) determination of the dependence of the resulting disturbances on the type of lightning discharges; (4) development of the theoretiaal framework upon which spectroscopic measurements of the airglow enhancements can be based to remotely diagnose the ambient electron density profiles; and (5) assessment of the effects of the lightning electromagnetic pulses on the thermal and chemical balance of the upper atmosphere on a global scale.
