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A triggered lightning flash (TLF) provides a unique perspective on the relationship between spatiotemporal proximity flashes, owing to its determined location and time, convenient direction measurement, and explicit association with the charge region. In this study, 3-D lightning location, current measurement, and atmospheric average electric field (AAEF) data were used to investigate the spatiotemporal relationship of TLFs (68 samples in South China) with adjacent natural lightning flashes (NLFs). The TLF-related negative charge regions had an average core height of 5.2 km and ambient temperature of approximately −1.7 °C. The effective negative charge region (the charge density that was high enough for the occurrence of lightning discharge) can be approximately equivalent to a circle with an average diameter of 10.3 km. For approximately 93% of (all) the TLFs, no NLF channel (initiation) was located within 5 km of the flash-triggered position, within 5 s before and after their occurrence. In situations where spatiotemporally adjacent NLFs and TLFs occurred, they were either associated with different charge layers or the same charge layer but different charge positions. Most NLFs that caused significantly sharp AAEF changes just before or after the TLFs were not associated with the TLF-related negative charge. Therefore, the recovery of the AAEF, which has usually been referenced as the timing choice of the triggering operation, was not directly associated with the TLF-related charge region. The average interval between the TLFs and NLFs that occurred within 10 min before and after the TLFs and neutralized the TLF-related negative charge was approximately 145 s.

Lightning-generated nitrogen oxides (LNO x ) have a major influence on the atmosphere and global climate change. Therefore, it is of great importance to obtain a more accurate estimation of LNO x . The aim of this study is to provide a reference for the accurate estimation of the total LNO x in the mainland of China based on cloud-to-ground lightning (CG) location data from 2014 to 2018. The energy of each CG flash was based on the number of return strokes per CG flash, the peak current of each return stroke, and the assumed CG breakdown voltage. The energy of intracloud lightning (IC) was based on the estimated frequencies of IC and the assumed energy of each IC flash. Combining the energy of lightning and the number of nitric oxide (NO) molecules produced by unit energy ( ρ no ), the total LNO x production in the mainland of China was determined. The LNO x in the mainland of China estimated in this study is in the range (0.157–0.321) × 10 9 kg per year [Tg(N) yr −1 ], which is on the high end of other scholars’ works. Negative cloud-to-ground lightning (NCG) flashes produce the most moles of NO x , while positive cloud-to-ground lightning (PCG) flashes produce the least total moles of NO x . The breakdown voltage of PCG is greater than that of IC or NCG, while the latter has a greater output of LNO x .

The equivalent propagation method adopts a variable propagation velocity in lightning location, minimizing the location error caused by various factors in the long-range lightning location network. To verify the feasibility of this method, we establish a long-range lightning location network in China. A new method is used to extract the ground wave peak points of the lightning sferics and is combined with the equivalent propagation velocity method for lightning location. By comparing with the lightning data detected by the lightning locating system called advanced direction and time-of-arrival detecting (ADTD) that has been widely used for tens of years in China, the feasibility of this method is initially verified. Additionally, it is found that the relative detection efficiency of our long-range lightning location network can reach 53%, the average location error is 9.17 km, and the detection range can reach more than 3000 km. The equivalent propagation method can improve the average location accuracy by ~1.16 km, compared with the assumed light speed of lightning-radiated sferic from the lightning stroke point to the observation station. The 50th percentile of the equal propagation velocity is 0.998c, which may be used in the long-range lightning location networks.

Lightning stroke strength, characterized by energy and peak currents, over the Tibetan Plateau (TP), is investigated by utilizing datasets from the World Wide Lightning Location Network and the Chinese Cloud-to-Ground Lightning Location System during 2016–2019. Focused on the south-central (SC) and southeast (SE) of the TP, it reveals that SE-TP experiences strokes with larger average energy and peak currents. Strong strokes (energy ≥ 100 kJ or peak currents ≥ |100| kA), exhibiting bimodal distribution in winter and summer, are more frequent and have larger average values over the SE-TP than the SC-TP, with diurnal distribution indicating peaks in energy and positive strokes in the middle of the night and negative strokes peaking in the morning. Utilizing the ECMWF/ERA-5 and MERRA-2 reanalysis, we find that stronger strokes correlate with thinner charge zone depths and larger CIWCFs but stable warm cloud depths and zero-degree levels over the SC-TP. Over the SE-TP, stronger strokes are associated with smaller CIWCFs and show turning points for warm cloud depths and zero-degree levels. Thicker charge zone depths correlate with stronger negative strokes but weaker positive strokes. Generating strokes of similar strength over the SC-TP requires larger CIWCFs, thinner warm cloud depths, and lower zero-degree levels than over the SE-TP.

Most lightning location networks obtain the position results by optimizing the goodness of fit to determine that all combinatorial time differences of arrivals (TDOAs) are due to a common discharge. This paper proposes a three-dimensional (3D) lightning location method based on range difference (RD) space projection. The proposed method projects all the measurements into the RD space, which has the space-invariant feature of the equivalence cell and can be partitioned soundly. Aiming at the problem of computational cost of the procedure of the projection, the hierarchical strategy is proposed to improve computational efficiency. The performance of the RD space projection based on the hierarchical strategy is analyzed via Monte-Carlo simulations. The results show that the proposed method can locate lightning sources in real time with high accuracy. The results also show that the location accuracy is limited by the level of the inherent time uncertainty, the layout, and the size of the receiver network. Under the fixed layout and size of the receiver network, and the fixed measurement noise uncertainty, the positioning precision cannot be improved more even if the grid step is small enough or the number of receivers is large enough.

In the summer of 2013, a three-dimensional (3D)-based Foshan Total Lightning Location System (FTLLS), embedded with differential time of arrival (DTOA) techniques, was installed and started its operation in Foshan, Guangdong Province, China. In this paper, the geographical distribution and set-up information of FTLLS, the estimated locating errors and locating results, as well as its initial operation results are presented. FTLLS consists of nine sub-stations that receive electromagnetic waves associated with lightning discharges and locates VLF/LF (200 Hz–500 kHz) radiation sources in 3D. The remote sub-stations acquired triggered waveforms with a duration of 0.5 ms, a resolution of 12-bits, and a GPS-based sferic time tags of 24 h per day. Cloud-to-ground (CG) lightning events, intra-cloud (IC) lightning events and narrow bipolar events (NBEs) were located by FTLLS. Based on the Monte Carlo simulation, the two-dimensional horizontal location error is basically less than 100 m, and the vertical error (altitude) is less than 200 m when the lightning event occurs within the network. On the other hand, over 14 million lightning strikes were recorded successfully by FTLLS during the period of May to October in 2014, among which IC events, CG events and NBEs accounted for 65%, 34% and 1%, respectively. It is shown that FTLLS is capable of a fine three-dimensional (3D) location, in which the altitude parameters obtained are reasonable and well consistent with observed data in the previous studies. The location results of thunderstorms were additionally verified through simultaneously-observed radar data.

We report the results of the use of the World Wide Lightning Location Network data to analyze the core structure of super typhoons that occurred in the northwestern Pacific Ocean in 2012–2013. The distributions of lightning discharges are compared to the ocean-surface wind fields according to the data of the Advanced Scatterometer (ASCAT) and the infrared images of the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the MetTop-A and Aqua satellites, respectively. In the central regions of all of the studied typhoons, the structures that are fragments of circular or spiral mesometeorological-scale forms, which can be related to the presence of the cloud eyewall of typhoons, are observed even a day before the typhoon’s maximum intensity. These circular structures become completely apparent on the day of the typhoon’s maximum intensity and then begin to break down. It is shown that the position of the center of a typhoon and its traveling speed can be estimated from the distribution of lightning; in addition, the geometric characteristics of an eyewall, which are listed in reports on storms and typhoons, can be determined.

On 15 January 2022, Hunga Volcano in Tonga produced the most violent eruption in the modern satellite era, sending a water‐rich plume at least 58 km high. Using a combination of satellite‐ and ground‐based sensors, we investigate the astonishing rate of volcanic lightning (>2,600 flashes min−1) and what it reveals about the dynamics of the submarine eruption. In map view, lightning locations form radially expanding rings. We show that the initial lightning ring is co‐located with an internal gravity wave traveling >80 m s−1 in the stratospheric umbrella cloud. Buoyant oscillations of the plume's overshooting top generated the gravity waves, which enhanced turbulent particle interactions and triggered high‐current electrical discharges at unusually high altitudes. Our analysis attributes the intense lightning activity to an exceptional mass eruption rate (>5 × 109 kg s−1), rapidly expanding umbrella cloud, and entrainment of abundant seawater vaporized from magma‐water interaction at the submarine vent. Plain Language Summary The eruption of Tonga's underwater Hunga Volcano culminated on 15 January 2022 with a giant volcanic plume that rose out of the ocean and into the mesosphere. This plume created record‐breaking amounts of volcanic lightning observed both from space and by radio antennas on the ground thousands of kilometers away. We show that the eruption created more lightning than any storm yet documented on Earth, including supercells and tropical cyclones. The volcanic plume rose to its maximum height and expanded outward as an umbrella cloud, creating fast‐moving concentric ripples known as gravity waves, analogous to a rock dropped in a pond. Point locations of lightning flashes also expanded outward in a pattern of donut‐shaped rings, following the movement of these ripples. Optically bright lightning was detected at unusually high altitudes, in regions of the volcanic cloud 20–30 km above sea level. Our findings show that a sufficiently powerful volcanic plume can create its own weather system, sustaining the conditions for electrical activity at heights and rates not previously observed. Overall, remote detection of lightning contributed to a detailed timeline of this historic eruption and, more broadly, provides a valuable tool for monitoring and nowcasting hazards of explosive volcanism worldwide. Key Points This eruption produced the most intense lightning rates ever documented in Earth's atmosphere Lightning rings expand with enormous gravity waves in the umbrella cloud, caused by buoyant oscillation of the overshooting plume top Volcanic lightning and satellite analysis reveal at least four phases of eruptive activity from 02:57–15:12 UTC on 15 January 2022

Cloud-to-ground (CG) lightning data from the European Cooperation for Lightning Detection (EUCLID) network over the period 2006–2014 are explored. Mean CG flash densities vary over the European continent, with the highest density of about 6 km−2 yr−1 found at the intersection of the borders between Austria, Italy and Slovenia. The majority of lightning activity takes place between May and September, accounting for 85 % of the total observed CG activity. Furthermore, the thunderstorm season reaches its highest activity in July, while the diurnal cycle peaks around 15:00 UTC. A difference between CG flashes over land and sea becomes apparent when looking at the peak current estimates. It is found that flashes with higher peak currents occur in greater proportion over sea than over land.