Diffusion model for lightning radiative transfer
| Autor: | Richard J. Blakeslee, William J. Koshak, Richard J. Solakiewicz, Dieudonne D. Phanord |
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| Rok vydání: | 1994 |
| Předmět: |
Atmospheric Science
Monte Carlo method Soil Science Aquatic Science Oceanography Physics::Geophysics Optics Geochemistry and Petrology Earth and Planetary Sciences (miscellaneous) Radiative transfer Neutron Earth-Surface Processes Water Science and Technology Physics Ecology business.industry Cloud top Paleontology Spherical harmonics Cloud physics Forestry Lightning Computational physics Geophysics Space and Planetary Science Light emission business |
| Zdroj: | Journal of Geophysical Research. 99:14361 |
| ISSN: | 0148-0227 |
| DOI: | 10.1029/94jd00022 |
| Popis: | A one-speed Boltzmann transport theory, with diffusion approximations, is applied to study the radiative transfer properties of lightning in optically thick thunderclouds. Near-infrared (lambda = 0.7774 micrometers) photons associated with a prominent oxygen emission triplet in the lightning spectrum are considered. Transient and spatially complex lightning radiation sources are placed inside a rectangular parallelepiped thundercloud geometry and the effects of multiple scattering are studied. The cloud is assumed to be composed of a homogeneous collection of identical spherical water droplets, each droplet a nearly conservative, anisotropic scatterer. Conceptually, we treat the thundercloud like a nuclear reactor, with photons replaced by neutrons, and utilize standard one-speed neutron diffusion techniques common in nuclear reactor analyses. Valid analytic results for the intensity distribution (expanded in spherical harmonics) are obtained for regions sufficiently far from sources. Model estimates of the arrival-time delay and pulse width broadening of lightning signals radiated from within the cloud are determined and the results are in good agreement with both experimental data and previous Monte Carlo estimates. Additional model studies of this kind will be used to study the general information content of cloud top lightning radiation signatures. |
| Databáze: | OpenAIRE |
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