Triangulation and Coupling of Gigantic Jets Near the Lower Ionosphere Altitudes

Coordinated TLE (transient luminous event) optical observations in Taiwan have been held since 2011, with an aim to achieve triangulation. Currently, there are four observation stations with baselines varying from 100 to 400 km between them. The system recorded eight gigantic jets (GJs) that were recorded by at least two stations on the night of 20 August 2014. The weather radar data indicate that these GJs occurred around the troposphere overshooting tops of a vigorous cumulonimbus cloud. A leader-to-streamer transition was discerned as the appearance of these GJs changed from jet-like (leader) to fan-like (streamer) at similar to 40 km altitude. Most of these GJs terminated at the lower ionosphere boundary (80-90 km), but one GJ topped with a 10 km thick diffuse region extended higher than 100 km. Moreover, three sets of the GJs occurred within 0.5-100 s in the same general region. The residual plasma patches from the preceding GJs appear to cause the subsequent GJs to contain more bead structures and to be brighter. Also, three streamer columns of a subsequent GJ that occurred more than 100 s after the preceding GJ were identified to have rebrightened at 55 to 70 km altitudes. The rebrightened streamers and the bead structure increments in the subsequent GJs suggest that there were GJ-produced long-lasting plasma patches in the mesosphere.