Triggered Negative Lightning‐Leaders That Propagated Into Thunderstorm Lower Positive Charge

Abstract

Triggered negative leader boundaries lie within low positive cloud boundaries • Lightning-charge densities (−4.2 to −1.8 C/km 3 ) are within the range of cloud-charge densities deduced from airborne measurements • Step recoil waves propagate farther than 3 km backward from negative leader steps

Polarity Asymmetries in Rocket‐Triggered Lightning

“…The red and blue dots in Figure 1e show the charge layers of the storm in which the negative leaders were triggered. The charge layers are determined from LMA source locations for about one hour of lightning activity around the instant of triggering (Winn et al., 2021, Figure 9). The negative leader plot of Figure 1c is reproduced in black dots overlaid in Figure 1e to show its location with respect to the thunderstorm charge.…”

“…In this investigation, we look at two flashes: the one with positive leaders was triggered on 15 August 2014 23:05 UTC, while the one with negative upward leaders took place on 23 July 2012 18:01 UTC. We report the current transferred to ground by the triggered flashes as measured with a 1 mΩ shunt resistor recording every 4 μs (Winn et al., 2021). Current measurements are stored in two channels: the insensitive channel measures currents up to 96 kA, while the sensitive channel can probe current levels as low as 0.1 A. Additionally, we report on the flashes' detailed structure as detected by up to 23 Lightning Mapping Array (LMA) stations around the triggering site (Rison et al., 1999; Thomas et al., 2001).…”

“…Observations were made from the Langmuir Laboratory mountain-top facility at 3.3 km altitude above sea level, which is located in central New Mexico, USA (34.06°N, 106.90°W). Lightning triggering via the rocket-and-wire technique has been done at Langmuir Lab since 1979, and detailed information about procedures and instrumentation can be found in the literature (Edens et al, 2012;Hubert et al, 1984;Idone et al, 1984;Winn et al, 2012Winn et al, , 2021. Rockets are launched from a platform atop the highest point in the Magdalena Mountains-South Baldy Peak.…”

“…Thus, the overwhelming majority of reports in the literature discusses triggered‐lightning flashes initiated by positive leaders, which after the initial leader phase are quite analogous to natural negative cloud‐to‐ground flashes (Rakov & Uman, 2003, Chapter 7). Meanwhile, reports of triggered lightning flashes with upward negative leaders remain scant in the literature (Fieux et al., 1975; Kawasaki & Mazur, 1992; Liu et al., 1994; Pu et al., 2017; Willett, 1992; Winn et al., 2021), which makes this type of comparison worthwhile.…”

Upward Lightning at the Gaisberg Tower: The Larger‐Scale Meteorological Influence on the Triggering Mode and Flash Type

“…In this context, another type of UL triggered by a rocket which is connected to the ground via wire has been comprehensively investigated. The benefit of predictability of rocket‐triggered over tower‐initiated UL has led to various studies conducted in the US (e.g., Bagheri et al., 2019 ; Kereszy et al., 2022 ; Miki et al., 2005 ; Winn et al., 2021 ) and in China (e.g., Fan et al., 2021 ; Jiang et al., 2020 ; Li et al., 2021 ). The properties of tower‐initiated and rocket‐triggered UL have been found to be very similar.…”