Do systematic differences in cloud-to-ground (CG) lightning properties-particularly return stroke number and current intensity-exist across different thunderstorm types? This question is foundational not only to the atmospheric electricity but also to advancing lightning risk prediction, which crucially depends on a robust understanding of how these physical attributes vary among thunderstorm types. This study compares CG lightning characteristics between frontal (FR) and warm-sector heavy rainfall (WR) events in Guangdong, China, using data from the Guangdong Lightning Location System from 2003 to 2014. Results show that WR events feature a higher positive CG (PCG) lightning percentage, more return strokes (RSs) of negative CG (NCG) lightning, and stronger NCG lightning currents, but lower CG lightning frequency compared to FR events. FR events exhibit higher peak currents in PCG compared to NCG lightning, while WR events show the opposite pattern. These differences remain consistent across the varying precipitation intensity bins used to classify the events. Additionally, WR events develop secondary peaks in the distributions of PCG lightning percentage, NCG RS number, and NCG lightning current as precipitation intensity increases, gradually approaching the decreasing peaks in FR events at higher precipitation intensities, leading to more similar CG lightning properties between the two event types. It is demonstrated that different types of thunderstorms can produce lightning discharges with distinct physical properties. Specifically, weaker convection may correlate with more RSs and greater current in NCG lightning. This finding offers valuable insights for the construction of future lightning risk predication.

Convective weather events accompanied by multiple tornadoes are rare. However, on 29 August 2019, a typhoon-induced squall line produced three tornadoes on Hainan Island. This rare event provides a valuable opportunity to investigate the microphysical characteristics and cloud-to-ground (CG) lightning activity during tornado periods. This research employed data from S-band dual-polarimetric Doppler weather radar and a VLF/LF three-dimensional lightning location system. Results showed that during the first tornado (developing stage), hydrometeor particles were sparse and dispersed, resulting in minimal CG lightning activity. In contrast, during the second tornado (mature stage), hydrometeor particles were abundant and concentrated, leading to the most active CG lightning. During the third tornado (dissipating stage), hydrometeor particles began to dissipate, though CG lightning activity remained higher than during the first tornado. The characteristics of hydrometeor particles and CG lightning in tornadoes were consistent with the concurrent developmental phase of the squall line. The rapid rise in the top altitude of the 40 dBZ echoes was a significant indicator of tornado formation. Furthermore, dry graupel, wet graupel, and dry snow particles exhibited strong correlations with CG lightning activity. These findings enhance our understanding of the microphysical and electrification mechanisms associated with tornadoes and provide valuable insights for improving tornado prediction.

This study utilizes data from a 3D lightning location system, polarimetric radar, and current measurements from channels of triggered lightning flashes (TLFs) to analyze the structural characteristics of the parent thunderstorms associated with negative TLFs in South China. The triggered-flash region (TFR) displays distinct stratiform cloud characteristics, including lower radar reflectivity heights and a predominance of ice crystals and dry snow above the 0°C layer. In contrast, the thunderstorm convection core region (CCR) tends to have more graupel particles in the mixed-phase layers and exhibits an ice-water content peak approximately 3.4 times that of the TFR. The charge regions involved in discharges in TFRs exhibit a dipolar charge structure, with the −5°C layer roughly dividing the upper positive and lower negative charge regions. Conversely, the CCRs feature a typical tripolar charge structure. The dominant dipole charge structure in the TFR results in an increase in the negative charge field below the negative charge region with height, providing a necessary condition for successfully triggering negative TLFs. Furthermore, the horizontal extent of TLFs is positively correlated with their duration and charge transfer. Regions where TLF channels with larger charge transfers propagate tend to have greater maximum radar reflectivity but lower average radar reflectivity compared to regions with TLFs with smaller charge transfer.

Based on three-dimensional lightning locations system and S-band dual-polarimetric Doppler radar data, the characteristics of lightning activity-dynamics-microphysical of a hailstorm that occurred on Hainan Island on 24 June 2021 was analyzed in detail. The analysis revealed that the lightning activity of hailstorm was dominated by intracloud lightning, which accounted for 85.38% of the total lightning. The cloud-to-ground lightning (CG) that occurred before the hailstorm was dominated by positive cloud-to-ground lightning (+CG). Before 25 min of the hailfall, 60% of the CG was +CG, which higher than normal thunderstorms. In the mature stage, the updraft intensified twice, at the meanwhile, the "lightning jump" lagged the updraft intensification. In addition, the increase and decrease of lightning frequency could be related to merger and separation of convection cell. Combined with the identification of precipitation particles within the cloud by the fuzzy logic method, the correlation coefficients between the total flashes and ice-phase hydrometeors were calculated, in which the graupel and ice-crystal particles more highly correlated with the total flashes, the correlation coefficients were 0.76 and 0.83, respectively. According to the spatial distribution characteristics of lightning radiation sources, it was inferred that the charge structure of hailstorm before the hailfall was anti-tripole charge structure. The positive charge area was located about between 7 to 9.5 km (about between -10 ℃ to -25 ℃).

Based on observed lightning locations and S-band polarimetric Doppler radar data, a hailstorm that occurred on Hainan Island was analyzed in detail. The hailstorm initially developed offshore to the southwest of Hainan Island. After the hailstorm made landfall, hail fell on the surface of Hainan Island for 43 min. An analysis revealed that the activity of cloud-to-ground flashes (CGs) peaked in the early mature stage of the hailstorm, followed by four intermittent CG flash active periods. The relationships between the CG flash frequency and the ice-phase hydrometeors retrieved from polarimetric parameters were compared, revealing that the CG flash activity was most closely related to graupel and snow particles in the cloud, whose correlation coefficients reached 0.8 and 0.76, respectively. In combination with the evolutionary features of the hailstorm, we found four independent periods of CG flash activity corresponding to different stages of the hailstorm: the merging of cloud bodies, the landfall of the convective body, the period of hailfall, and the period of orographic uplift. During these periods, the vertical distributions and concentrations of graupel and snow particles were distinct. During the hailfall period, the most significant vertical rate of change in radar echo intensities larger than 40 dBZ was located in the region of 0-10 degrees C, and this rate of change was the largest of the whole hailstorm.

In the summer of 2019, one case of electric field sounding in eyewall of No.1907 typhoon named Wipha was obtained in Wenchang, Hainan Island, China. Up to now, it has been the first case of electric field sounding results obtained in a typhoon system. In this paper, based on the observations of satellite, meteorological radar, ground electric field and cloud-to-ground flash location data of Hainan province, China, the basic characteristics of the typhoon are analyzed in detail. Owing to the limitation of cloud-to-ground flash location system, only flash activities of the typhoon before and after landing period are analyzed and the result does not show obvious features as reported by other researches. Referring to the radar reflectivity and sounding path, we confirm that the sounding penetrates through the eyewall region of the typhoon from cloud base to top. The electric field profile and the charge region distribution in the sounding path area are analyzed, and the results show that four positive and three negative charge regions exist between 5.74 and 9.10 km above sea level and the corresponding temperatures range from –2.4 to –16.7 ℃ of the seven charge regions. The mean charge densities of each charge region from bottom to top are 0.63 nC/m3, –0.33 nC/m3, 0.31 nC/m3, –1.03 nC/m3, 1.70 nC/m3, 1.57 nC/m3 and –1.20 nC/m3, respectively. According to the preliminary analysis, we consider that the two positive charge layers at the top should be in the same charge region. Under the comprehensive consideration of the thickness of charge regions, the intensities of these six charge regions are 0.33 nC/m2, –0.07 nC/m2, 0.06 nC/m2, –0.87 nC/m2, 0.73 nC/m2, and –0.18 nC/m2, respectively. We can find that there are three dominant charge regions with largest intensity and they are the lowest positive charge region, the middle main negative region, and upper main positive charge region. And these vertical distributions of the three dominant charge regions are characterized by a tripole charge structure. These results are basically consistent with some simulation results. In addition, a negative screen charge region with a shallow depth in a range of 15–20 dBZ of the upper cloud boundary can be found. Combining the popular charging mechanisms, the similarity of tripole charge structure between our sounding and normal thunderstorm are discussed, and we preliminary consider that the non-inductive charging mechanism and the inductive charging mechanism, which originate from normal convection, are also suitable for eyewall region of typhoon.

利用闪电定位、天气雷达和大气探空等多源资料,结合海南岛西北部7个区域的自动气象站资料,对2020年在海南岛西北部首次出现的两次雷暴天气过程(2020-02-13-2020-02-14)进行了综合分析,同时对雷暴形成的大气环境要素特征进行了统计.结果表明:两次雷暴所对应的地闪活动和回波强度存在一定的差异,第二次雷暴过程的平均地闪频数和不同阶段的回波强度都较第一次大,但第一次雷暴的正地闪比例较高,达到了46％,第二次雷暴对应的正地闪则只占9％.通过对2月份温度和湿度的日变化统计发现,雷暴活动期间的气温整体要高于晴天和阴雨天的气温,午后气温的增温趋势也更为明显;而在14:00时之前,其相对湿度也是整体高于晴天和阴雨天的相对湿度.探空资料的结果显示,对流有效位能、云底高度以及中层平均相对湿度都可作为指示对流活动的指标,但中层平均相对湿度更为合理.

In order to directly observe the electric field characteristics and study the charge structure in thunderstorms occurring in tropical regions, a balloon-borne strong electric field sounding is used to measure the vertical component of the electric field, temperature within the cloud and real-time location information of the sounding. Based on the principle of corona discharge, two 1-m-long metal probes are used as the sensors to detect the vertical electric field. In the summer of 2019, a result of electric field sounding within a local thunderstorm was obtained in the northeastern coastal area of Hainan Island, China. With the combination of an S-band weather radar, atmospheric electric field instrument and lightning locating network, the charge structure of the thunderstorm is analyzed in detail. The results show that the thunderstorm is a small-scaled local thunderstorm occurring in the afternoon, the sounding starting to be observed at the decay stage of the thunderstorm. In this period, lightning activities is rare, and the variation of ground electric field is similar to that of conventional summer thunderstorms. The whole sounding process lasts 34 min, during which the vertical airflow in the cloud is relatively stable, basically keeping 4–6 m/s. It can be seen from the electric field profile that the charge distribution in the thunderstorm cloud shows a complex charge structure which is composed of six charge regions. A negative charge region is lowermost, and above this the polarity alternates successively from bottom to up, where all charge regions are located above the melting-layer. Due to data interruption, it is impossible to accurately judge the upper boundary of the upper negative charge region and the information about the positive charge region above. The remaining charge regions are located in an altitude range of 6.0–6.3 km, 6.3–6.6 km, 6.9–7.3 km and 7.3–8.3 km, respectively. The charge densities in these four regions are –1.84 nC/m3, 1.80 nC/m3, –1.46 nC/m3, and 1.04 nC/m3, respectively. According to the existing data, the charge density of the uppermost negative charge area should be greater than –0.51 nC/m3. Moreover, the upper positive charge region (the fourth from bottom up) has the largest strength, followed by the negative charge region above it, both of which are more than 1 km in thickness. The electric field intensities in the other charge regions are relatively small. The pairs of positive and negative charge regions at the bottom are slightly different in strength and thickness.

基于小波分析方法,通过对7种小波函数在误差控制和阈值方法选取上的对比,参考信噪比及均方误差等计算结果,选取了较为合理的Rigrsure阈值分析方法和sym5小波函数作为地面大气电场信号的去噪处理方法.该方法不仅能够较好地对电场信号波形平滑处理,降低电场波形中噪声信号的叠加度,还可保留闪电引起的电场的快速变化.在此基础上,利用差分计算方法实现了对闪电信号的自动识别,引入了总闪电频数误差及分时段闪电频数与人工分析结果的相关系数等2个参考量来选取差分计算方法中电场差分阈值,通过该方法可以实现闪电频数和极性等有关信息的提取.

Electric field (E) sounding data was obtained in one case of local thunderstorm in Qinghai region in summer of 2016. Combining the radar data and cloud-to-ground (CG) flashes location data, the CG flashes activities and charge structure of the thunderstorm were studied in detail. The results show that the evolution of negative CGs is intermittently and the spatial distribution is discontinuously. All the positive CG flashes occurred in the mature stage of thunderstorm. Electric field sounding data was obtained in the transitional period of the mature stage and the dissipating stage, and charge regions in the thunderstorm were figured out based on the vertical E profile. Totally four charge regions were found in the thunderstorm and charge polarities were alternate in a vertical direction with a negative charge region at the lowest in the warm cloud region. The upper boundary of the upper positive region was unknown because the sounding data was missed, the altitudes of other three charge regions were at 5. 5 similar to 5. 7 km (3.4 similar to 2.3 degrees C), 5. 7 similar to 6. 2 km (2. 3 similar to -0. 4 degrees C) and 6. 2 similar to 6. 6 km (-0. 9 similar to -1.7 degrees C), and their charge densities were -1.81 nC . m(3), 2.47 nC . m(3) and -1.76 nC . m(3), respectively. The relationship between positive CG flashes and charge structure was analyzed, and we speculated that the formation of a negative charge layer in the warm cloud region was in favor of causing the positive CG flashes from the lower positive charge region.

The World Wide Lightning Location Network (WWLLN) data was used to analyze the lightning activities of Tropical Storm Bebinca (2013) and Super Typhoon Rammasun (2014). The relationships between lightning activity and cyclonic intensity change, direction of storm motion of the two tropical cyclones were also investigated. Preliminary analyses showed that the two systems produced a large number of lightning strokes in the region of $0\sim800\ km$ from the centers, the numbers are 111,289 and 125,046 for Bebinca and Rammasun, and the average lightning stroke rate of Bebinca was 1021 str/h and that of Rammasun was 680 str/h. Both for Bebinca and Rammasun, their lightning frequency were oscillating in the whole lives, however, it was varied little for Rammasun and decreased for Bebinca. The radial and spatial distribution of lightning showed that the lightning of Bebinca mainly appeared at rain band outside of 300 km and most of lightning occurred at the west of cyclone. For Rammasun, lightning mainly produced in the regions of 160 km away from center, including the inner rainband and outer rainband, and mainly centralized in the west of cyclone. When the area around each storm was divided into four quadrants with respect to storm motion, right and left front, and right and left rear, the maximum number of flashes occurred in the left-rear quadrant of Bebinca, while in the right-front and left-front quadrant of Rammasun. The relationship between lightning frequency and intensity change for Bebinca was weak, while strong for Rammasun. The moving directions of Bebinca and Rammasun exhibited a weak relationship with lightning frequency, but well correlated with lightning spatial distribution.

A balloon-borne sounding system was designed to measure the vertical electric field, humidity, temperature and precipitation particle (size and type of ice phase) within thunderstorm. Based on the principle of GPS tracking, a ground-based automatic tracking and transceiver system (hereinafter referred to as the ground system) was designed to receive all signals transmitted from the sounding continuously. Some results obtained by this system had been introduced in this paper. A result of a sounding measurement in Aug.22 2016 in the inland plateau of China shows that total four charge regions were found in the mature stage of a thunderstorm and charge polarity was alternate in a vertical direction with a negative charge region at the lowest in the warm cloud region. Another result of a sounding measurement in Aug.26 2018, obtained above the tropical island of China, shows that at the dissipation stage of the thunderstorm, there is a positive polar charge zone in the warm cloud, while there is a strong negative charge zone near 0\square level and a positive charge zone above. This system could adapt to different environments and obtain valid data of electric field (E). However, in actual observation, there was still some shortness in obtaining the information of ice phase particles image.

利用海南省气象局在海南岛内布设的地闪定位网、海口地区组网大气平均电场仪及雷达对超强台风“威马逊”过程的监测资料,分析了该过程在海南岛过境(2014年18日12时至19日12时)时陆地及附近海域的地闪活动的时空分布特征.闪电监测结果显示,18日18时起,发生的地闪数目开始增多,至18日22时达到顶峰,至19日8时以前仍保持较强的频数.地电主要发生在东方市境内及近海,最大密度值出现于洋面,达到了4.7次/km2(海面),陆地最大地闪密度为1.6次/km2.通过对地面电场的演变特征分析来看,嵌于台风外围雨带里的对流云具有三极性电荷结构特征,这与大部分常规夏季雷暴云具有一致性.

A sounding system with electrical field and precipitation particles in thunderstorm is used for measuring humidity, temperature, the vertical component of electric field (E-field) and particle video. The ground system is used to continuously receive several signals sent by the sounding by tracking the GPS information carried by the sounding. This sounding system operated in a public frequency band of 2.4 GHz and used a fixed channel with the bandwidth of 20MHz to realize the point-to-point full-duplex communication. The ground system was connected to a parabolic directional antenna with high-gain of 27dBi. The real test showed that the maximum communication distance is about 15km which can well guarantee the field observation. The sounding was composed of GPS, temperature and humidity sensors, airborne vertical electric field measurement device, and precipitation particle video device.. GPS signal is very important for locating the balloon position and synchronously tracing sounding by antenna, and the measurement of vertical electric field used the corona probe as the sensor, and the ice phase precipitation particles were captured by a camera with frame rate of 25fl/s. A case of thunderstorm was obtained in the Pingliang of China. The results indicated that the balloon ascend through seven charge areas. A negative one located close to ground and a positive zone was above it in the warm cloud area. Other zones appeared at the area above melting layer and polarity of these was alternative changing. Another case showed the thunderstorm should have four charge regions with the lowest one is negative. However in actual observation, it still exists insufficient in recording the information of ice phase particles.

A balloon-borne instrument was designed to measure the electric field in thunderstorms. One case of thunderstorm was observed in the Pingliang region (35.57 degrees N, 106.59 degrees E; and 1620m above sea level, a.s.l.) of a Chinese inland plateau, through penetration by the balloon-borne sounding in the early period of the mature stage. Results showed that the sounding passed through seven predominant charge regions. A negative charge region with a depth of 800m located near the surface, and a positive charge region appeared in the warm cloud region; their mean charge densities were -0.44 +/- 0.136 and 0.43 +/- 0.103 nCm(-3), respectively. Five charge regions existed in the region colder than 0 degrees C, and charge polarity alternated in a vertical direction with a positive charge at the lowest region. The mean charge densities for these five regions were 0.40 +/- 0.037 nCm(-3) (-9.5 to -4 degrees C), -0.63 +/- 0.0107 nCm(-3) (-18 to 1-4 degrees C), 0.35 +/- 0.063 nCm(-3) -(27 to -18 degrees C), -0.36 +/- 0.057 nCm(-3) (-34 to -27 degrees C), and 0.24 +/- 0.06 nCm(-3) (-38 to -34 degrees C). We speculated that the two independent positive charge regions in the lower portion are the same charge region with a weak charge density layer in the middle. The analysis showed that the real charge structure of the thunderstorm is more complex than the tripole model, and the lower dipole is the most intensive charge region in the thunderstorm.

利用自行研制的闪电VHF辐射源功率接收系统,对青藏高原东北部闪电VHF辐射源功率三维分布进行了观测,初步分析了雷暴电荷结构,并利用自行研制的中心频率为270 MHz球载闪电模拟源,对闪电VHF辐射源功率接收系统进行了野外标定,得到了267 ～ 273 MHz频率范围的闪电辐射脉冲功率三维时空发展分布图.统计结果显示,在正云闪中,上部正电荷区平均辐射脉冲功率为4.8W,下部负电荷区平均辐射脉冲功率为1.6W,上部正电荷区的辐射功率明显高于下部负电荷区.在负云闪中,下部正电荷区平均辐射脉冲功率为3.2W,上部负电荷区平均辐射脉冲功率为2.5W,下部正电荷区的辐射功率明显高于上部负电荷区.在负地闪中,负电荷区平均值为3.0W,正电荷区平均辐射脉冲功率为4.7W.负电荷区辐射源数都少于正电荷区,绝大多数正电荷区的平均辐射脉冲功率大于负电荷区,但个别闪电的负电荷区平均辐射脉冲功率大于正电荷区.

利用海南省地闪定位网获取的4年(2010年1月至2013年12月)地闪定位资料,详细分析海南岛地闪活动的时空分布特征,结果显示,海南岛的地闪活动主要发生在4-10月;呈双峰特征,峰值分别出现于5月和8月,分别约占全年总地闪数的23％和18％;地闪活动在6-7月明显地间歇性减少.从日变化特征来看,地闪在14:00-20:00时段最为频繁.16:00左右达到峰值,而5:00左右有一个较弱的峰值,2个峰值所占比例分别约为11.3％和4.2％.通过对比分析各地区的地闪活动,发现日变化呈现双峰特征的区域主要集中在东、南和西部沿海地区,而中部内陆及靠近琼州海峡的北部沿海地区呈单峰值特征.海南岛中部内陆山区的地闪密度大,沿海地区地闪密度小,并且存在2个地闪密度高值区.

A local severe thunderstorm, occurring near the coastal region in Fujian province, China, was chosen to study the relationships between hydrometeors and cloud-to-ground (CG) flash activities. This thunderstorm case study was carried out by using vehicle-mounted X-band dual-polarization radar on August 28, 2009. On the basis of polarimetric parameters, the hydrometeors were identified by fuzzy logic hydrometeor classification (FLHC). The results show that the thunderstorm grew into a squall line with a maximum flash rate of 85fl/5min in mature stage. Negative CG constituted approximately 97.3% of total CG flashes. More than 90% of the CG flashes occurred in the convective regions, and less than 10% occurred in the stratiform region. The strong echo volume in convective region had a positive linear correlation with the CG flashes rate. Seven types of hydrometeors, namely, rain (RN), aggregates (AG), low-density graupel (LDG), high-density graupel (HDG), vertically aligned ice crystals (VI), drizzle-light rain (DR), and ice crystals (IC), have been classified; the first five of the hydrometeors are predominant in the thunderstorm. RN is located mainly in regions warmer than 0°C; the HDG is located in the middle and lower regions colder than 0°C; and LDG and VI mainly appear in the upper portion of the thunderstorm. The ice hydrometeors seemly had a close relation with CG flashes because the total CG flash rates had a strong positive correlation with the grid number of AG, LDG, HDG, and VI in the convective region. However, the sufficient ice hydrometeors did not produce frequent CG flashes in the stratiform region. It suggests that the dynamic structure is also very important for triggering lightning flashes.

An electric field sounding system, based on corona discharge, was designed to measure the vertical component of the electric fields in a thunderstorm. The decay stage of a thunderstorm that occurred during the night of August 20, 2012, in the Pingliang region, China (35.57°N, 106.59°E, 1620m above sea level (asl)), was investigated by two balloon-borne electrical soundings. The results of the first sounding showed that the thunderstorm had a tripole charge structure: a lower positive charge region located at temperatures of 3 to 15°C (2.0–4.0kmasl); a middle negative charge region located at temperatures of −3 to 3°C (4.5–5.3kmasl); and an upper positive charge region at temperatures of −10 to −3°C (5.3–6.3kmasl). In addition, there was a negative screen layer at the bottom of the thunderstorm with a depth of about 400m. The charge density of the middle negative charge region was larger than that of the lower and upper positive charge regions. Influenced by the downdraft of precipitation, each charge region moved down to a lower altitude region. The results of the second sounding showed that the lower positive charge center totally disappeared and only the middle negative charge region (3.7–4.2kmasl) and upper positive charge region (4.2–4.7kmasl) remained. We conclude that the downdraft with precipitation caused the dissipation of the lower positive charge region. Compared with the first sounding result, we found that the charge density increased and the depth decreased for both of the charge regions.

Based on the cloud-to-ground (CG) flashes data from 2010 to 2013 obtained- by the VLF lightning locating networks in Hainan Province, the temporal and spatial characteristics of cloud-to-ground (CG) flashes activities were analyzed. The results indicated that more than 99% of CG flashes occurred between April and October and two peaks of CG activity appeared in May (23%) and August (30%).The CG flashes occur clearly with a characteristic of daily and monthly variation, in which there are two peaks. The peaks of daily variation occur at 5:00 am and 16:00 (Beijing time) almost. In terms of areas, the CG activities in the most coastal areas present the changing characteristic of double peaks. However, there is only a single peak in the inland areas and the northern coastal areas near the Qingzhou Strait. The first peak (the early peak) occur between 2:00 and 7:00 am, and the second one (the late peak) occur during the period from 12:00 to 17:00, where the CG activities present the double-peak characteristic. The spatial distribution of CG flashes presents certain regularity that the CG flashes density is the largest in the inland mountainous areas and the density becomes more and more small as the spatial position further outspread forward the coastal areas. In addition, there are two high value centers of the CG flashes density, and the spatial distribution of flashes density exist differences at different times especially in the south of Hainan Island and on the north of Wuzhishan mountain.