Upward electrical discharges observed above Tropical Depression Dorian
Dwyer, Joseph R.
Rassoul, Hamid K.
Cummer, Steven A.
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Observation of upward electrical discharges from thunderstorms has been sporadically reported in the scientific literature. According to their terminal altitudes, they are classified as starters (20-30km), jets (40-50km) and gigantic jets (70-90km). They not only have a significant impact on the occupied atmospheric volumes but also electrically couple different atmospheric regions. However, as they are rare and unpredictable, our knowledge of them has been built on observations that typically record only one type of such discharges. Here we report a close-distance observation of seven upward discharges including one starter, two jets and four gigantic jets above Tropical Depression Dorian. Our optical and electromagnetic data indicate that all events are of negative polarity, suggesting they are initiated in the same thundercloud charge region. The data also indicate that the lightning-like discharge channel can extend above thunderclouds by about 30km, but the discharge does not emit low-frequency electromagnetic radiation as normal lightning. © 2015 Macmillan Publishers Limited. All rights reserved.