Understanding the Parametric Dependencies of the Lightning Optical Signature: Results From a Hydrodynamic Modeling Study
Abstract
While there is strong current interest in the remote sensing of lightning RF signals for severe weather monitoring, the lightning optical signature has received, comparatively, less attention. Understanding the physical processes that control the power, decay and spectral content of the optical signature is, fundamentally, a problem in shock physics. After a brief period (on the order of microseconds) the hydrodynamic expansion of the return-stroke channel develops into a shock, described by Rankine-Hugoniot jump conditions, that is relatively insensitive to the precise spatial distribution of the initial loading. Thus the shock propagation and the cooling of the channel by radiation and expansion evolves in a predictable fashion that has implications for the remote sensing and spectroscopic assessment of lightning events. In this work, we present results from a first-principles radiation hydrodynamic model of the return-stroke channel that is used to simulate a broad range of channel initial conditions. We then analyze the simulated optical signatures within the theoretical framework of jump-conditions and self-similar shock profiles which provides insights into the relevant parametric dependencies.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFMAE21A0997Z
- Keywords:
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- 3324 Lightning