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Lightning mapping of five flashes showing five-layer charge structure at 2210 UTC 29 Jun 2000. (top) Altitude vs time with a label for each flash. (lower) Three different spatial projections along with an altitude histogram of the number of sources. LMA sources are color-coded by inferred ambient charge region, with black for positive and gray for negative. Flashes 1, 2, and 4 are inverted flashes (negative over positive charge). Flashes 3 and 5 are normal flashes (positive over negative).
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This second part of a two-part study examines the lightning and charge structure evolution of the 29 June 2000 tornadic supercell observed during the Severe Thunderstorm Electrification and Precipitation Study (STEPS). Data from the National Lightning Detection Network and the New Mexico Tech Lightning Mapping Array (LMA) are used to quantify the t...
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... illustrate the LMA-inferred charge structure methodology, Fig. 1 shows lightning mapping of a five- flash sequence during this storm, which reveals five ver- tically stacked charge regions, alternating in polarity with positive as the lowest. The sources are color-coded by inferred ambient charge region to highlight the stratified structure. Figure 2 shows the second flash of the five-flash ...
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... flash. The sparse grouping of sources at 6-7 km MSL maps out the inferred negative charge below the positive. Such flashes are termed normal IC flashes as they reveal a normal dipole structure. Hence, the location of the positive charge was consistently revealed by both of these flashes. The remaining flashes of the five-flash sequence in Fig. 1 were similarly clear, with each show- ing distinct bilevel structure. When put together, they reveal a very clear and consistent picture of the charge ...
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... extent in apparent re- sponse to bursts in updraft, with the density of LMA sources closely tracking graupel echo volume in both time and height (cf., e.g., the contours of graupel echo volume to those of LMA sources in Fig. 6). On a few occasions, strong bursts of updraft led to numerous LMA sources (from tens to hundreds of sources, or 15-25 Fig. 1. This is a normal flash that initiated upward from an inferred ambient negative charge region into an inferred ambient positive charge region. LMA sources are color- coded by time from blue to red. dB min 1 ) extending as high as 15 km MSL (see, e.g., around 2330 and 2400 UTC in Fig. 6). Such vertically elevated LMA sources in response ...
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... since these multiple strike points originated from the same flash, they were assumed to share a common ori- gin for the purposes of computing the mean origin height. Figure 10 shows an altitude histogram of these CG flash origin heights, for both positive and negative polarity CG flashes. The CG origin heights are also overlaid onto the time-height contours of Fig. 6b. ...
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... illustrate the evolution of precipitation and elec- trical structure in the storm, Figs. 11-13 show represen- tative horizontal and vertical cross sections of radar reflectivity and LMA source density during selected volume scans, along with a composite schematic of the charge structure inferred from lightning mapping of many individual lightning flashes. The LMA density plots in these figures are not exactly cross sections per ...
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... originate in the elevated precipitation east of the updraft; they then propagated down through the inferred lower positive charge region associated with descending precipitation. The three flashes that occurred from 2140 to 2144 UTC are representative of this early lightning activity. Their LMA sources are overlaid onto the bottom-left panel of Fig. 11. This ar- rangement of charge could be described as an inverted dipole; however, the two charge regions involved in this early lightning activity might correspond to the lowest ...
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... overall the LMA-inferred charge structure con- sisted of a lower inverted dipole, an upper inverted dipole, and an additional positive charge at the top. Figure 14 shows lightning mapping of five successive flashes (from 2200:46 to 2200:59 UTC) that spanned these five inferred charge regions. As illustrated by the charge composite and vertical cross section of LMA source density in Fig. 11 (second column, bottom two panels), the lightning flashes from 2155 to 2210 UTC were all consistent with this basic five-layer structure. ...
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... con- sisted of a lower inverted dipole, an upper inverted dipole, and an additional positive charge at the top. Figure 14 shows lightning mapping of five successive flashes (from 2200:46 to 2200:59 UTC) that spanned these five inferred charge regions. As illustrated by the charge composite and vertical cross section of LMA source density in Fig. 11 (second column, bottom two panels), the lightning flashes from 2155 to 2210 UTC were all consistent with this basic five-layer structure. Most of the flashes occurred in the charge regions of the upper inverted dipole, leading to a pronounced peak in LMA source density in the upper positive charge, with a secondary peak corresponding ...
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... 2159 to 2213 UTC, as the updrafts waned and the lofted precipitation grew and descended, the light- ning continued to show five-layer charge structure (e.g., Fig. 1), though more compressed. There were also more normal IC flashes connecting the negative charge of the lower inverted dipole to the positive charge of the up- per inverted dipole (e.g., Fig. 3). In other words, the two dipole charge regions no longer remained separate. However, flashes in the upper inverted dipole still dominated the ...
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... charge regions no longer remained separate. However, flashes in the upper inverted dipole still dominated the lightning activity. By 2220 UTC, there was still some semblance of a four-layer alternating charge structure. However, the charge regions were more compressed with a pronounced downward sloping east-southeastward away from the updraft (Fig. 11, third column, bottom two panels). The lower positive charge was more restricted near the precipitation core, as if the largest hydrometeors were carrying this lower positive charge with it to ground, while the charge (pre- sumably carried by smaller particles) in the next three alternating regions (negative/positive/negative) sloped ...
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... three alternating regions (negative/positive/negative) sloped downward more gradually further downwind. Indeed, the lower negative charge formed a very low-level (4-5 km) stratified layer extending well southeast of the bulk of the lightning activity. This southeastward extension is not apparent in the vertical cross sections in the third column Fig. 11 (because the associated LMA sources are too far away from the cross-section plane to be included in the plot) but can be inferred from the hori- zontal cross section in the second ...
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... association with the strong updraft on the western edge of the storm. The lightning activity mirrored the reflectivity structure of this BWER, with almost no lightning activity within the BWER (consti- tuting a midlevel lightning hole, for lack of better term) and very active lightning in the strong lofted echo above and to the south of the BWER (Fig. 12, left column). The lightning was very frequent, making LMA-based charge structure determination much more difficult. However, the vast majority of the flashes near and within the echo vault surrounding the BWER were inverted IC flashes, leading to the inference of a four- layer alternating charge structure near the main up- draft. The positive ...
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... the vast majority of the flashes near and within the echo vault surrounding the BWER were inverted IC flashes, leading to the inference of a four- layer alternating charge structure near the main up- draft. The positive charge regions of this structure cor- respond to the two prominent peaks of LMA source density in the vertical cross section of Fig. 12 (left col- umn, bottom two panels). As at 2220 UTC, the upper- inverted dipole persisted downwind (east-southeast) and sloped downward, while the charge structure in the lower part of the storm was more complex (or at least more difficult to determine). However, there was a handful of normal IC flashes to the near southeast of the ...
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... downwind (east-southeast) and sloped downward, while the charge structure in the lower part of the storm was more complex (or at least more difficult to determine). However, there was a handful of normal IC flashes to the near southeast of the precipitation core revealing positive charge at 6.5- 10 km MSL and negative charge below (e.g., Fig. 15). The first two CG flashes of the storm (Fig. 16) orig- inated from the same region as these normal IC flashes (though on the northwest edge of this region), and struck ground just southeast of the surface hail swath. Prior to their return strokes, the structure of these two CG flashes was very similar to the preceding normal IC ...
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... while the charge structure in the lower part of the storm was more complex (or at least more difficult to determine). However, there was a handful of normal IC flashes to the near southeast of the precipitation core revealing positive charge at 6.5- 10 km MSL and negative charge below (e.g., Fig. 15). The first two CG flashes of the storm (Fig. 16) orig- inated from the same region as these normal IC flashes (though on the northwest edge of this region), and struck ground just southeast of the surface hail swath. Prior to their return strokes, the structure of these two CG flashes was very similar to the preceding normal IC flashes shown in Fig. 15. That is, the initial negative ...
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... The first two CG flashes of the storm (Fig. 16) orig- inated from the same region as these normal IC flashes (though on the northwest edge of this region), and struck ground just southeast of the surface hail swath. Prior to their return strokes, the structure of these two CG flashes was very similar to the preceding normal IC flashes shown in Fig. 15. That is, the initial negative breakdown of both the normal IC and the CG flashes progressed upward, defining positive charge at 6.5-10 km MSL, with later breakdown below the initiation point through negative charge below. Additionally, the CG flashes also appeared to tap some positive charge further west within the precipitation core ...
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... 2246 to 2252 UTC, hail continued to grow and descend giving a deep hail shaft and relative maximum in hail echo at 2246 UTC (Fig. 6). TFR decreased to 50 min 1 . As shown in Fig. 17, the lightning tended to avoid the 55 dBZ hail shaft almost entirely during this time, again suggesting that hail plays a minimal role in charge separation. By 2259 UTC, the hail had almost all fallen out, and the bulk of the lightning activity was again nearer the precipitation core, but was very con- centrated above the collapsing ...
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... 17, the lightning tended to avoid the 55 dBZ hail shaft almost entirely during this time, again suggesting that hail plays a minimal role in charge separation. By 2259 UTC, the hail had almost all fallen out, and the bulk of the lightning activity was again nearer the precipitation core, but was very con- centrated above the collapsing hail shaft (Fig. 12, middle column). Overall, the LMA indicated an in- verted tripole with inferred positive charge region cen- tered at 8-10-km altitude and negative charge regions above and below. Though a lower negative charge was present beneath the midlevel positive, this charge struc- ture did not produce CG flashes. During the brief decline in updraft and hail ...
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... storm and charge structure at the beginning of the severe right mature phase (2325 UTC) was in many ways similar to that at 2239 UTC. A strong, broad up- draft on the western flank was coincident with an echo vault and midlevel BWER (Fig. 12, right column). As discussed in Part I, the flow diverged around the up- draft, particularly to the south, leading to a reflectivity maximum southeast of the main updraft. Again, the lightning density mirrored the reflectivity structure in the mid-to upper levels (cf. the top two panels of the right column of Fig. 12). A pronounced midlevel light- ...
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... echo vault and midlevel BWER (Fig. 12, right column). As discussed in Part I, the flow diverged around the up- draft, particularly to the south, leading to a reflectivity maximum southeast of the main updraft. Again, the lightning density mirrored the reflectivity structure in the mid-to upper levels (cf. the top two panels of the right column of Fig. 12). A pronounced midlevel light- ning "hole" was coincident with the midlevel BWER, with active lightning above and downwind (especially southeast) of the BWER. As with 2239 UTC, the TFR increased dramatically (to nearly 150 min 1 ), and the storm began producing frequent CG ...
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... much of the lightning within the echo vault above the updraft consisted of compact flashes lacking clear vertical charge structure, there were still many flashes indicating an inverted dipole structure here and in the upper levels farther downwind (Fig. 12, bottom right panel). In addition, relatively infrequent normal IC flashes continued to indicate the presence of lower negative charge just downwind of the precipitation core. The seven CG flashes during the 2325 UTC volume scan struck ground in two clusters. Each cluster appeared to be associated with the separate diverging flows ...
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... around the updraft, with one cluster of three CG flashes along the northeast path, and the other cluster of four CG flashes along the more dominant southeast path. The initial negative breakdown of all seven CG flashes progressed upward from 6-7 km into a distinct midlevel maximum of LMA density (positive charge) just downwind of the hail shaft (Fig. 12, right column, bottom two panels). Following their return strokes, most of them tapped additional midlevel positive charge extending south and east, but rarely extended back westward into the more intense precipi- tation. Leading up to the peaks in hail echo volume and CG flash rate at 2343-2351 UTC, the majority of CG flashes ...
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... up to the peaks in hail echo volume and CG flash rate at 2343-2351 UTC, the majority of CG flashes continued to cluster (in both origin and strike location) on the downwind side of the hail shaft along these divergent flow paths, tapping positive charge at 6.5-10 km MSL. Figure 18 shows a particu- larly clear example. ...
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... 2351 UTC, the BWER had filled in with large hydrometeors, and the lightning activity had wrapped around it, leading to a pronounced peak in LMA den- sity on the western side of the updraft (Fig. 13, left column, top two panels). Flashes in this western portion of the hail shaft generally indicated an inverted dipole with a deep (5-9 km MSL) positive charge region below a negative charge region (Fig. 13, bottom left panel). The two CG flashes that struck south of the updraft tapped this deep positive charge region. The remainder of the ...
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... and the lightning activity had wrapped around it, leading to a pronounced peak in LMA den- sity on the western side of the updraft (Fig. 13, left column, top two panels). Flashes in this western portion of the hail shaft generally indicated an inverted dipole with a deep (5-9 km MSL) positive charge region below a negative charge region (Fig. 13, bottom left panel). The two CG flashes that struck south of the updraft tapped this deep positive charge region. The remainder of the CG flashes also showed limited propagation into the positive charge in the hail shaft, but the ma- jority of the breakdown continued to be through midlevel positive charge extending eastward from the downwind edge of the ...
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... at 5-7 km and positive charge at 7-9 km, which roughly corresponds to the midlevel charge structure inferred from the downward balloon sounding. How- ever, a half dozen or so CG flashes initiated to the south-southeast of the hail, with little discernible struc- ture other than extensive low-level breakdown back westward into the hail core (e.g., Fig. 19). This extreme lower-level charge may correspond to the lowest posi- tive charge region of the balloon sounding. Comparison of the lightning mapping with the balloon sounding is difficult, however, because the LMA-inferred charge structure varied greatly in the horizontal while the bal- loon measured only along its flight ...
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... the radar volume scan at 0030 UTC, the CG flash rate peaked and the CG strikes clustered along a roughly north-south line 5-15 km east of the elon- gated hail shaft (Fig. 13, middle column). Exterior to the updraft and hail core, the lightning-mapped struc- ture of the flashes was relatively consistent and re- vealed a basic inverted tripole charge structure. Keep- ing with the recurring theme of this storm, the initial inferred negative breakdown of most of the CG flashes progressed upward into the eastern, downward- ...
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... activity steadily descended (Fig. 6b). Dur- ing the last volume scan of the observation period (0115 UTC), the CG flash rate reached its absolute maxi- mum, and all but four of the 23 CG flashes from 0115 to 0120 UTC struck ground in a very tight cluster nearly coincident with the hail swath beneath a very dense concentration of LMA sources (Fig. 13, right column). The CG flashes were so clustered that it is difficult to resolve the individual strike points or to discern the underlying storm structure in this figure. In contrast to earlier times, almost all of these CG flashes tapped the inferred positive charge in the hail shaft (e.g., Fig. 21), though some also continued to tap into midlevel ...
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... a very dense concentration of LMA sources (Fig. 13, right column). The CG flashes were so clustered that it is difficult to resolve the individual strike points or to discern the underlying storm structure in this figure. In contrast to earlier times, almost all of these CG flashes tapped the inferred positive charge in the hail shaft (e.g., Fig. 21), though some also continued to tap into midlevel (6-8 km MSL) positive charge further east, downwind of the hail shaft. Of the two CG flashes during this time, one struck in the hail shaft and one northeast of it. Both initiated near 9 km MSL, atop the LMA density maximum (Fig. 13, right column, third and fourth pan- ...
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... tapped the inferred positive charge in the hail shaft (e.g., Fig. 21), though some also continued to tap into midlevel (6-8 km MSL) positive charge further east, downwind of the hail shaft. Of the two CG flashes during this time, one struck in the hail shaft and one northeast of it. Both initiated near 9 km MSL, atop the LMA density maximum (Fig. 13, right column, third and fourth pan- ...
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... In addition, graupel echo volume (CSU GEV; km 3 ) and 35 dBZ echo volume (CSU 35EV; km 3 ), which are similar to PIM and have previously shown strong correlations to lightning (Carey & Rutledge, 1996;Liu et al., 2012;Wiens et al., 2005), were also used to develop FRPSs for Colorado storms. To calculate the storm parameters, data points were restricted to the mixed-phase region of convective clouds (i.e., 5°C > temperature > 40°C and reflectivity > 35 dBZ). ...
Eighteen lightning flash rate parameterization schemes (FRPSs) were investigated in a Weather Research and Forecasting model coupled with chemistry cloud‐resolved simulation of the 29–30 May 2012 supercell storm system observed during the Deep Convective Clouds and Chemistry (DC3) field campaign. Most of the observed storm's meteorological conditions were well represented when the model simulation included both convective damping and lightning data assimilation techniques. Newly‐developed FRPSs based on DC3 radar observations and Lightning Mapping Array data are implemented in the model, along with previously developed schemes from the literature. The schemes are based on relationships between lightning and various kinematic, structural, and microphysical thunderstorm characteristics (e.g., cloud top height, hydrometeors, reflectivity, and vertical velocity) available in the model. The results suggest the model‐simulated graupel and snow/ice hydrometeors require scaling factors to more closely represent proxy observations. The model‐simulated lightning flash trends and total flashes generated by each scheme over the simulation period are compared with observations from the central Oklahoma Lightning Mapping Array. For this supercell system, 13 of the 18 schemes overpredicted flashes by >100% with the group of FRPSs based on storm kinematics and structure (particularly updraft volume) performing slightly better than the hydrometeor‐based schemes. During the storm's first 4 hr, the upward cloud ice flux FRPS, which is based on the combination of vertical velocity and hydrometeors, well represents the observed total flashes and flash rate trend; while, the updraft volume scheme well represents the observed flash rate peak and subsequent sharp decline in flash rate.
... Additionally, anomalous charge structures have been found to produce significant lightning flash rates (Fuchs et al., 2015) and severe weather (Lang & Rutledge, 2011), with predominantly positive CG flashes (Carey & Buffalo, 2007;Lang et al., 2004;Lang & Rutledge, 2011;Tessendorf et al., 2007;Wiens et al., 2005). Indeed, instead of being located at the upper part of the cloud, the main positive charge layer is located at the middle or lower level, which facilitates the positive leaders to propagate to the ground and even more easily if a layer of negative charges is present between the main positive charge layer and the ground. ...
... Nonetheless, some of these anomalous storms exhibit low flash rates and no positive CG flash predominance. Anomalous charge structures have been observed in the US (Chmielewski et al., 2018;Fuchs et al., 2015Fuchs et al., , 2016Fuchs et al., , 2018Lang et al., 2004;MacGorman et al., 2008;Rust et al., 2005;Stough & Carey, 2020;Stough et al., 2021;Tessendorf et al., 2007;Wiens et al., 2005), in Spain (Pineda et al., 2016;Salvador et al., 2021) or in Argentina (Lang et al., 2020;Medina et al., 2021). ...
... In order to remove the number of noisy sources, only VHF sources detected by a minimum of 7 stations and with a reduced-chi square lower than 0.5 are kept similarly to Coquillat et al. (2019). In addition, flashes with less than 10 VHF sources are also filtered out (e.g., Mecikalski et al., 2017;Salvador et al., 2021;Schultz et al., 2015;Wiens et al., 2005). About 84.2% of the flashes recorded during the study period are filtered out with 93.6% (93.5%) of them having a flash duration lower than 1 ms (100 µs). ...
Lightning characteristics of Corsican storms with different charge structures are investigated in this study. Observations of an LMA network are used to document the total lightning activity. Complementary lightning observations of the lightning detection network Météorage are also used. A clustering algorithm is used to build a database of electrical cells from June to October 2018. A method is also applied to infer the vertical charge structure, as dominant dipoles, per 10‐min period for each electrical cell. As an example, one cell recorded in July 2018 is discussed. The cell database is then presented as well as the main electrical properties according to the dominant charge structures. For instance, the higher in altitude the dominant dipole, the higher the flash rate. Overall, dominant negative dipole are observed for 25% of the 10‐min periods and can be separated into two categories: (a) low altitude negative dipole class dominated by negative cloud‐to‐ground (CG) flashes with a main positive layer located between 2 and 4 km height and (b) high altitude negative dipole class, dominated by negative intracloud (IC) with a main positive layer at 5 km height. Dominant positive dipole can also be separated into two categories with (a) a dominant positive dipole located between 4.5 and 10 km high, −CG dominance, weak flash rate and (b) higher altitude dominant positive dipole, +IC dominance and a larger +CG fraction. The synergistic use of LMA and Météorage observations independently gives a rational type and polarity classification with regard to the vertical charge structure.
... From 17:37 UTC, between the surface and the −40 • C level, there is reflectivity above 60 dBZ. These high reflectivity values suggest the existence of large droplets within the cloud and/or the presence of hail inside the cloud, with the potential for severe events such as heavy rain and lightning [59,[83][84][85]. Figure 12n). The increase in lightning near the hail moment is because, at this moment of the storm, the updrafts are more intense, promoting the collision of hydrometeors and inducing the charging and separation of charges within the storm clouds [80][81][82]. ...
... From 17:37 UTC, between the surface and the −40 °C level, there is reflectivity above 60 dBZ. These high reflectivity values suggest the existence of large droplets within the cloud and/or the presence of hail inside the cloud, with the potential for severe events such as heavy rain and lightning [59,[83][84][85]. Furthermore, the reflectivity above 45 dBZ exceeds the −40 °C level close to 17:37 UTC. ...
Thunderstorms can generate intense electrical activity, hail, and result in substantial economic and human losses. The development of very short-term forecasting tools (nowcasting) is essential to provide information to alert systems in order to mobilize most efficiently the population. However, the development of nowcasting tools depends on a better understanding of the physics and microphysics of clouds and lightning formation and evolution. In this context, the objectives of this study are: (a) to describe the environmental conditions that led to a genesis of a thunderstorm that produce hail on 7 January 2012, in the Metropolitan Area of São Paulo (MASP) during the CHUVA-Vale campaign, and (b) to evaluate the thunderstorm microphysical properties and vertical structure of electrical charge. Data from different sources were used: field campaign data, such as S-band radar, and 2- and 3-dimensional lightning networks, satellite data from the Geostationary Operational Environmental Satellite-13 (GOES-13), the Meteosat Second Generation (MSG), and reanalysis of the European Centre for Medium-Range Weather Forecasts Reanalysis v5 (ERA5). The thunderstorm developed in a region of low-pressure due to the presence of a near-surface inverted trough and moisture convergence, which favored convection. Convective Available Potential Energy (CAPE) of 1053.6 J kg−1 at the start of the thunderstorm indicated that strong convective energy was present. Microphysical variables such as Vertically Integrated Liquid water content (VIL) and Vertically Integrated Ice (VII) showed peaks of 140 and 130 kg m−2, respectively, before the hail reached the surface, followed by a decrease, indicating content removal from within the clouds to the ground surface. The thunderstorm charge structure evolved from a dipolar structure (with a negative center between 4 and 6 km and a positive center between 8 and 10 km) to a tripolar structure (negative center between 6 and 7.5 km) in the most intense phase. The first lightning peak (100 flashes in 5 min−1) before the hail showed that there had been a lightning jump. The maximum lightning occurred around 18:17 UTC, with approximately 350 flashes 5 min−1 with values higher than 4000 sources 500 m−1 in 5 min−1. Likewise, the vertical cross-sections indicated that the lightning occurred ahead of the thunderstorm’s displacement (maximum reflectivity), which could be useful in predicting these events.
... Obtaining high-quality wind retrievals with sufficient resolution for cloud analysis requires proper positioning and spacing of radar observing sites, which are currently lacking even in the SMA region. In Fig. 10, we depict the expected updraft information with an orange-dashed arrow based on previous research on updrafts and lightning (Solomon and Baker 1998;Wiens et al. 2005;Schultz et al. 2017;Stough et al. 2022). These studies have shown that an updraft volume of ≥ 10 m s −1 (the value may vary between studies) above the melting layer is a more favorable condition for lightning occurrence compared to considering the maximum or average velocity . ...
On August 8 and 9, 2022, a record-breaking rain rate of 142 mm h ⁻¹ , with an accumulated rainfall of more than 500 mm, was observed in the Seoul metropolitan area, Republic of Korea. This study focuses on analyzing the concentration of lightning in southern Seoul, which occurred solely on August 8. It is worth noting that the daily rainfall of August 8 was approximately twice that of August 9 (381 mm on August 8 vs. 198 mm on August 9). The RKSG (located in Yongin, 40 km south of Seoul) Weather Surveillance Radar-1988 Doppler was used to explore the characteristics of cloud microphysics associated with lightning activity. Four major heavy rain periods on August 8 were grouped into three categories of lightning rate (e.g., intense, moderate, and none), and their polarimetric signatures were compared. Significant differences in the vertical distribution of graupel were found within the temperature range of 0 °C and − 20 °C, as indicated by radar reflectivity (Z H ) > 40 dBZ and differential reflectivity (Z DR ) < 0.5 dB. Although graupel was detected in all three categories at the relatively warm temperatures of 0 °C to − 10 °C, its presence extended into colder regions exclusively in the intense category. This observation preceded the appearance of lightning by approximately 6 min. At heights with temperature ≤ − 20 °C, a high concentration of vertically aligned ice crystals was observed in lightning-prone regions, leading to a decrease in differential phase (Φ DP ). In summary, this study provides valuable insights into the microphysical characteristics of thunderstorms and their relationship to lightning activity in the Seoul metropolitan area.
... Previous studies have shown that PCG flashes usually account for approximately 10% of all CG flashes (Orville & Huffines, 1999;Yang et al., 2015;Zajac & Rutledge, 2001), but the proportion of PCG flashes may vary greatly during the evolution of a thunderstorm (Zheng et al., 2010). Severe weather (large hail and tornadoes) produced by thunderstorms may be accompanied by a predominance of PCG lightning (Carey & Rutledge, 1998;Lang et al., 2004;Macgorman & Burgess, 1994;Wiens et al., 2005) or occur without dominant PCG lighting (Carey & Rutledge, 2003;Williams, 2001). In general, the CG polarity in severe convective storms shows large variability (Pineda et al., 2016). ...
Plain Language Summary
Thunderstorms are known as a type of weather system that is typically accompanied by the presence of lighting and other hazardous weather (high winds, heavy rain, hail and tornadoes). Cloud‐to‐ground (CG) lighting produced by thunderstorms is a highly dangerous weather phenomenon that occurs between a thundercloud and the ground and often causes wildfires, explosions and severe damage to buildings. The middle reaches of the Yangtze River Basin in China are a transition zone between plateaus and plains, with dense urban agglomerations, rivers and lakes. However, thunderstorm activity in such complex underlying surfaces is poorly understood. Based on ground‐based radar and lightning observations, the statistical characteristics of thunderstorm activity in this region during the warm seasons (May to September) of 2016–2020 are analyzed using a lightning clustering method. The CG lighting number, area and displacement of thunderstorms increase with thunderstorm duration. Thunderstorms that last longer are mostly triggered near the mountains and often start earlier in the afternoon and end later in the evening. In addition, CG lighting produced by thunderstorms is associated with high radar echo intensity. These findings are useful for improving the nowcasting of lightning and other hazardous weather caused by thunderstorms.
... Lightning marked the inception of the eruption and evolved in space and time producing characteristic ring patterns centered over the volcanic vent 8,16,17 (Fig. 1). Gaps in the volume-filling lightning activity of large supercell storms have been described before 18,19 and interpreted as due to localized regions of strong updraft within the thunderstorm. However, meteorological lightning discharges have never showed such regular symmetry, extension, or periodicity as those produced during the HTHH eruption. ...
... Bôr et al. 14 , who reported detailed observations of HTHH lightning, compared the lightning rings with a very active supercell during thunderstorms and linked them with updraft surges. The lack of lightning activity within confined regions of thunderstorm clouds ("lightning holes") has been observed in supercell systems 18,19 and has been interpreted as an indicator of severe weather conditions. Such lightning holes are known to drift with time, coinciding with regions of strong updraft within the cloud. ...
Hunga Tonga-Hunga Ha’apai (HTHH), a submarine caldera volcano of the Tonga archipelago, erupted explosively on January 15, 2022. The eruption generated the highest concentration of lightning events ever recorded, producing characteristic ring patterns of electrical discharges concentric to the vent. Here we reproduce the key features of the observations using three-dimensional simulations of buoyant plumes in a stably stratified atmosphere. Our idealized minimal model based on the Boussinesq approximation and heavy particles reveals that the essential mechanism underlying the formation of lightning rings is turbulence-induced particle clustering, which generates structures, favorable conditions for charge concentration by particle collision. We propose that the location, size, and persistence of lightning ring structures can reveal pulsatory activity at the vent that the opaque ash cloud hides from the satellite observation and can be used as a proxy for eruption parameters regulating the generation of hazardous impacts on the environment.
... An increase in the number of positive cloud-to-ground (+CG) strokes during severe storms has often been observed (Wiens et al. 2005; reference therein). To explain the charge structure leading to +CG stroke-dominated thunderstorms, the following four hypotheses were summarized (see Williams 2001): ...
... Fujiwara et al. (2021) compared similar-sized hailfall and rainfall cells, which occur at roughly the same time in locations near the Tokyo metropolitan area in Japan with practically the same meteorological conditions. Their investigations of two cases in 2014 and 2017 revealed that the number of ±CG strokes in the rainfall cells was twice as high as that in the hailfall cells, as is shown by Wiens et al. (2005). It was also found that the ice volume in the hailfall cells was greater than that in the rainfall cells. ...
According to newspapers, hailfall of up to 3–4 cm in diameter was observed in the afternoon of May 4, 2019 in Tokyo, Japan. The thunderstorm cell split into two during the hailfall period, with one propagating northward with hailfall and the other propagating southward with only rainfall. For these two cells, we investigated the number of cloud-to-ground (CG) strokes identified by the lightning detection network, the temporal changes in the ice volume derived from the X-band multi-parameter radar data, and atmospheric electric fields. The results showed that the ice volume of the cell with hailfall (hailfall cell) was greater than that of the cell without hailfall (rainfall cell), whereas the number of CG strokes in the hailfall cell was smaller than that in the rainfall cell. In addition, –CG strokes were more dominant in the rainfall cell than in the hailfall cell, while +CG strokes were more dominant in the hailfall cell than in the rainfall cell. This implies that there was a large loss in negatively charged hail in the hailfall cell due to gravity, which led to an increase in net positive charge in the hailfall cell, causing +CG strokes.
... A downward leader which effectively lowers positive charges from the cloud to the ground is known as positive cloud-to-ground lightning (+CG) and accounts for approximately 10% of the total cloud-to-ground lightning (Rakov, 2003). A few earlier studies have shown that +CG lightning can dominate the total CG lightning activity in some severe thunderstorms (Rust and MacGorman, 2002;MacGorman and Burgess, 1994;Lang et al., 2004;Rust et al., 2005;and Wiens et al., 2005). Also, a few studies such as Rutledge and MacGorman (1988) and Rutledge and Petersen (1994) have shown that the trailing stratiform regions of the mesoscale convective systems (MCS) produce dominant +CG lightning. ...
... Most lightning flashes concentrate in the convective region with strong radar echo greater than 30 dBZ. Different lightning parameterization schemes have been established based on the relationship between lightning frequency and dynamical factors, such as cloud-top height (CTH), the maximum updraft velocity [25], the volume of ice particles, and the radar echo volume in the mixed-phase region [26,27]. ...
... According to the charge transfer after the collision between different categories of hydrometeor particles, electrical parameters can be directly obtained based on the simulation by different models coupled with the electrification charging mechanism and lightning discharge parameterization [26,[28][29][30][31]. Mansell et al. [29] simulated the electrical parameters, including charge structure, electric field and lightning frequency by lightning discharge parameterization, and different non-inductive charging schemes. ...
Based on three-dimensional lightning data and an S-band Doppler radar, a strong relationship was identified between lightning activity and the radar volume of squall lines. A detailed analysis of the squall line investigates the relationship following an exponential relationship. According to the correlation between lightning and the radar volume, three radar-volume-based lightning parameterization schemes, named the V30dBZ, V35dBZ, and V40dBZ lightning schemes, have been established and introduced into the weather research and forecasting (WRF) model. The performance of lightning precondition by different lightning parameterization schemes was evaluated, including the radar-volume-based schemes (V30dBZ, V35dBZ, and V40dBZ), as well as existing lightning schemes (PR92_1, PR92_2, and the Lightning Potential Index (LPI)). The evaluation shows that the simulated spatial lightning density and temporal lightning frequency by the radar-volume-based lightning schemes are more consistent with the observations. While the two PR_92 lightning schemes significantly underestimated the magnitude of lightning density. The radar-volume-based lightning parameterization schemes are proven to be more reliable in estimating lightning activity than other lightning schemes.
... (i) a positive anomaly in the CG activity (more positive CGs) (Soula et al. 2004, Wiens et al. 2005), due to a change in the cloud electrical structure (Bruning et al. 2014) and (ii) periods of almost no CG activity during the hail shaft, related to a decrease of the electrification related to the hailstone growth (e.g. Jayaratne and Saunders 2014). ...
... is above 1. A positive anomaly is when this ratio is below 1, a pattern that has been related to severe weather (Soula et al. 2004, Wiens et al. 2005), due to a change in the cloud's electrical structure (Bruning et al. 2014). ...
... There was a second cycle of maximum-minimum before the second hailfall occurred, which produced large hailstones. The positive anomaly observed in the CG lightning fraction during the second hailfall period is consistent with severity in thunderstorms (Soula et al. 2004, Wiens et al. 2005), due to a change in the cloud's electrical structure (Bruning et al. 2014). ...
