Characteristics of Lightning Within Electrified Snowfall Events Using Lightning Mapping Arrays

Abstract

This study examined 34 lightning flashes within four separate thundersnow events derived from lightning mapping arrays (LMAs) in northern Alabama, central Oklahoma, and Washington DC. The goals were to characterize the in‐cloud component of each lightning flash, as well as the correspondence between the LMA observations and lightning data taken from national lightning networks like the National Lightning Detection Network (NLDN). Individual flashes were examined in detail to highlight several observations within the data set. The study results demonstrated that the structures of these flashes were primarily normal polarity. The mean area encompassed by this set of flashes is 375 km2, with a maximum flash extent of 2,300 km2, a minimum of 3 km2, and a median of 128 km2. An average of 2.29 NLDN flashes were recorded per LMA‐derived lightning flash. A maximum of 11 NLDN flashes were recorded in association with a single LMA‐derived flash on 10 January 2011. Additionally, seven of the 34 flashes in the study contain zero NLDN‐identified flashes. Eleven of the 34 flashes initiated from tall human‐made objects (e.g., communication towers). In at least six lightning flashes, the NLDN detected a return stroke from the cloud back to the tower and not the initial upward leader. This study also discusses lightning's interaction with the human‐built environment and provides an example of lightning within heavy snowfall observed by Geostationary Operational Environmental Satellite‐16's Geostationary Lightning Mapper.

Geographical Distribution of Thundersnow Events and Their Properties From GPM Ku‐Band Radar

“…Another item of interest is that about 20% of CG snow lightning has positive flashes, which is more than twice when compared to warm CG lightning flashes (8%, Table ). This fits with recent analysis by Schultz et al (), which showed that 21 of the 30 flashes observed in their thundersnow study were negative (70%), while remaining 30% flashes were positive. Pettegrew () showed that about 8% of the thundersnow lightning flashes were positive based on a 14‐storm study over the central United States.…”

Charge Regions Indicated by LMA Lightning Flashes in Hokuriku's Winter Thunderstorms

“…If only referring to the vertical arrangements of the charge regions included in discharges, the charge structures contained quad‐polar structures (Figures a1 and b2; the charges from top to bottom were positive, negative, positive, and negative), tripolar structures (Figures a2 and b3; upper positive, middle negative, and lower positive), dipolar structures (Figures b1 (the main part), 21c1, 21c2, and 21c3; upper positive and lower negative), inverted dipolar structures (Figures a4, c4, and c5; upper negative and lower positive) and inverted tripolar structures (Figures a3, b4, b5, and c6; upper negative, middle positive, and lower negative). In contrast, in most previous studies, winter thunderstorms were suggested to have dipolar or tripolar charge structures (Brook et al, ; Caicedo et al, ; Kumjian & Deierling, ; Schultz et al, ; Takahashi et al, , , ), which was similar to normal summer thunderstorms (Williams, ). As we mentioned in the beginning of section , due to the limit of the observation range of the LMA and the rapid movement of thunderstorms, the cells producing the investigated flashes might be in different development stages; therefore, the diverse patterns of the charge distributions, as shown in sections – and summarized in Figure , might have resulted from both the differences in diverse cells and distinct evolution stages.…”

“…The LMA sources can only indicate the charge regions taking part in lightning discharges, which is more different from the observations of sounding through the storm (e.g., Takahashi et al, 1999Takahashi et al, , 2017Takahashi et al, , 2018 (Figures 21a3, 21b4, 21b5, and 21c6; upper negative, middle positive, and lower negative). In contrast, in most previous studies, winter thunderstorms were suggested to have dipolar or tripolar charge structures (Brook et al, 1982;Caicedo et al, 2018;Kumjian & Deierling, 2015;Schultz et al, 2018;Takahashi et al, 1999Takahashi et al, , 2017Takahashi et al, , 2018, which was similar to normal summer thunderstorms (Williams, 1989). As we mentioned in the beginning of section 3, due to the limit of the observation range of the LMA and the rapid movement of thunderstorms, the cells producing the investigated flashes might be in different development stages; therefore, the diverse patterns of the charge distributions, as shown in sections 3.1-3.3 and summarized in Figure 21, might have resulted from both the differences in diverse cells and distinct evolution stages.…”

“…The properties of flash including duration, horizontal distance, and area of the convex hull are also investigated. The flash spatial size can be a proxy for the extent scale of valid charge regions for lightning propagation, a concept employed in previous studies on electrical summer storms (e.g., Bruning & MacGorman, 2013;Calhoun et al, 2013;Zhang et al, 2017a;Zheng et al, 2018;Zheng & MacGorman, 2016) and winter storms (e.g., López et al, 2017;Schultz et al, 2018;Yoshida et al, 2018). The flash duration indicates the time difference between the last source and the first source.…”

Polarimetric radar characteristics of lightning initiation and propagating channels

“…Within the context of another measurement campaign in the US planes, the Severe Thunderstorm Electrification and Precipitation Study (STEPS) (Lang et al, 2004), observations were presented about storms with normal and inverted polarity (Tessendorf et al, 2007). More recently, Kumjian and Deierling (2015) and Schultz et al (2018) examined lightning-producing snow storms.…”