Modeling the Transmission of Optical Lightning Signals through Complex
Three-Dimensional Cloud Scenes
Space-based lightning imagers have shown that complex cloud scenes that
consist of multiple tall convective features, anvil clouds, and warm
boundary cloud layers are illuminated by lightning in many different
ways, depending on where the lightning occurs and how energetic it is.
Modifications to the optical lightning signals from radiative transfer
in the cloud medium can lead to reductions in detection efficiency and
location accuracy for these instruments, and can also cause some of the
optical signals that are detected to have unexpected spatial energy
distributions. In this study, we perform Monte Carlo radiative transfer
simulations of optical lightning emissions in clouds with complex
three-dimensional geometries to shed some light on the origins of
certain irregular radiance patterns that have been recorded from orbit.
We show that reflections off nearby cloud faces can explain lightning
signals in non-electrified clouds, tall clouds can result in poor
optical transmission and suppressed radiances that could lead to missed
events, and that particularly favorable viewing conditions can cause
otherwise normal lightning to produce a “superbolt” that is orders of
magnitude brighter than the same flash seen from a different direction.