The Illumination of Thunderclouds by Lightning: 1. The Extent and Altitude of Optical Lightning Sources

Abstract

Lightning flashes are comprised of vast networks of hot ionized plasma channels (da Silva et al., 2019) that extend over tens or even hundreds of kilometers (

The Illumination of Thunderclouds by Lightning: 3. Retrieving Optical Source Altitude

“…We propose that altitude information can be extracted from GLM measurements of how the surrounding thunderclouds are illuminated by lightning. Our previous modeling work (Peterson, 2020a ) demonstrated that low‐altitude sources result in different spatial radiance patterns than high‐altitude sources regardless of cloud geometry, and this was confirmed with GLM observations in and Part 1 of this series (Peterson et al., 2021a ). Our discussion of “optical repeater” flashes in Peterson et al.…”

“…Our discussion of “optical repeater” flashes in Peterson et al. ( 2021a ) and previous analyses of groups with complex spatial radiance distributions (Peterson, 2020b ) further showed that radiance patterns were consistent between subsequent illuminations of the same cloud layer. However, these pictures of cloud illumination would change if the flash moved into a different layer, for example, during cases in Peterson et al.…”

“…The most accurate three‐dimensional source information is provided by Lightning Mapping Arrays (LMAs: Rison et al., 1999 ) whose effective range is limited to just a few hundred kilometers. The only truly global lightning network that attempts to resolve altitude is the Earth Networks Global Lightning Network (ENGLN: Zhu et al., 2017 ), but their intracloud (IC) altitude parameter is not well refined, leading to highly inaccurate results (Peterson et al., 2021a ).…”

FORTE Measurements of Global Optical Lightning Waveforms and Implications for Optical Lightning Detection

“…As the optical emissions from these sources become spread over a larger number of pixels, a smaller fraction of the total pulse signal is used for detection. Since most optical sources are small (Peterson et al, 2022a), the impact on instrument performance is anticipated to depend on the amount of spatial broadening in the signals from scattering in the clouds, further amplifying the existing detection advantage for high-altitude sources (that are less modified by scattering in the cloud medium) over low-altitude sources (that are severely broadened). However, if the low-altitude pulses could still be detected with a finer-resolution instrument, the greater detail in the measured spatial energy distributions would be beneficial for applications that use this product (Peterson, 2019(Peterson, , 2021aPeterson et al, 2022bPeterson et al, , 2022cPeterson & Mach, 2022).…”

The Illumination of Thunderclouds by Lightning: 2. The Effect of GLM Instrument Threshold on Detection and Clustering

“…This is the second part of our thundercloud illumination study. In Part 1 (Peterson et al., 2021a ), we examined how the positions and geometries of optical sources affected GLM measurements of cloud illumination. In Part 2, we shift our focus from the emitter to the GLM instrument and quantify the effects of the GLM threshold on event/group/flash detection, flash clustering, and gridded product generation.…”