Upward electrical discharges observed above Tropical Depression Dorian

Abstract

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 (20–30 km), jets (40–50 km) and gigantic jets (70–90 km). 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 30 km, but the discharge does not emit low-frequency electromagnetic radiation as normal lightning.

A Thermodynamic, kinematic and microphysical analysis of a jet and gigantic jet‐producing Florida thunderstorm

“…Given that strong mixing at storm top is likely the norm, it follows that positive jets initiated near the screening layer are less common [Krehbiel et al, 2008;Riousset et al, 2010;Edens, 2011]. However, as reported by Liu et al [2015], the seven Dorian related jets are all of negative polarity-indicating that (1) they share the same formation Figure 1. The 3 August 2013 event locations (numbered, see Table 1).…”

“…Whether the leaders develop into a BFB, jet, or GJ is an ongoing debate. In recently published work involving the same Florida storm discussed here, Liu et al [2015] indicate that this may ultimately depend on the length of the leader path through the cloud charge region. In an interesting study involving a dual-Doppler analysis of a high precipitation Oklahoma supercell, Calhoun et al [2013] found that the near core flashes were of "smaller horizontal extent" when compared to flashes elsewhere (e.g., anvil region)-presumably due to pockets of charge in various portions of their storm.…”

“…On the evening of 3 August 2013 a series of seven negative polarity jet events occurred in a 26 min period off the central east coast of Florida [Liu et al, 2015]. Using video from two cameras, National Lightning Detection Network (NLDN) lightning locations and the star field, Liu et al [2015] derive both the heights and locations.…”

“…Using video from two cameras, National Lightning Detection Network (NLDN) lightning locations and the star field, Liu et al [2015] derive both the heights and locations. Events 1 and 3 terminated at 51-55 km altitude, the tops of events 2, 5, 6, and 7 were outside the field of view of the camera, resulting in a terminal altitude greater than 77-82 km while event 4 terminated at about 26 km altitude.…”

Sprite possibly produced by two distinct positive cloud-to-ground lightning flashes

“…Up to now, the TLE family includes sprites (Sentman et al 1995;Lyons 1996;Winckler et al 1996;Cummer et al 2006;Yang et al 2008;Savtchenko et al 2009;Lang et al 2010;Suzuki et al 2011;Boggs et al 2016;Peng et al 2017), elves (Emissions of Light and VLF perturbation due to EMP Sources) Barrington-Leigh et al 2001;Kuo et al 2007;Wu et al 2017), halos ), blue starters, blue jets and gigantic jets (Pasko 2003;Su et al 2003;Kuo et al 2009;Chou et al 2011;Yang and Feng 2012;Liu et al 2015b). Sprites are usually produced by intense lightning discharges and are observed between about 40 -90 km altitude above thunderstorms (Sentman et al 1995;Hardman et al 2000;Neubert et al 2001;Su et al 2002;Pinto et al 2004;Cummer et al 2006; Van der Velde et al 2006;Yang et al 2008Yang et al , 2013aYang et al , 2015Lu et al 2017).…”