Wave optics modeling of solar eclipse shadow bands

摘要

Just preceding and following the occurrence of a total solar eclipse, thin, wavy ribbons of light known as “shadow bands” have been observed on the ground. Codona (Astronomy and Astrophysics 164, 415–427, 1986) presented a theoretical investigation that suggests the turbulence mainly responsible for shadow band is found to be within the bottom 2–3 kilometers of the atmosphere. In this paper, a novel approach is proposed to model the shadow band phenomena using a numerical wave optics simulation. The simulation approach employs numerical wave optics techniques to model a crescent-shape source, propagation of the light through turbulence, and collection of the light at the ground, where the atmospheric turbulence below 3 kilometers is modeled with a set of phase screens. The simulation produces intensity patterns, structures, motion and evolution of shadow bands that are in agreement with the theoretical predications and with actual observations during an eclipse. Our results support Conoda's theory and the modeling approach provides a powerful tool to study the effects of specific atmospheric conditions on shadow bands and other extended sources.