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 thunde...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℃ 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℃ 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.展开更多
Thunderstorms of pre-monsoon season (April – May) over Kolkata (22° 32’N, 88° 20’E), India are invariably accompanied with lightning flashes, high wind gusts, torrential rainfall, occasional hail and torn...Thunderstorms of pre-monsoon season (April – May) over Kolkata (22° 32’N, 88° 20’E), India are invariably accompanied with lightning flashes, high wind gusts, torrential rainfall, occasional hail and tornadoes which significantly affect the life and property on the ground and aviation aloft. The societal and economic impact due to such storms made accurate prediction of the weather phenomenon a serious concern for the meteorologists of India. The initiation of such storms requires sufficient moisture in lower troposphere, high surface temperature, conditional instability and a source of lift to initiate the convection. Convective available potential energy (CAPE) is a measure of the energy realized when conditional instability is released. It plays an important role in meso-scale convective systems. Convective inhibition energy (CINE) on the other hand acts as a possible barrier to the release of convection even in the presence of high value of CAPE. The main idea of the present study is to see whether a consistent quantitative range of CAPE and CINE can be identified for the prevalence of such thunderstorms that may aid in operational forecast. A statistical – fuzzy coupled method is implemented for the purpose. The result reveals that a definite range of CINE within 0 – 150 Jkg-1 is reasonably pertinent whereas no such range of CAPE depicts any consistency for the occurrence of severe thunderstorms over Kolkata. The measure of CINE mainly depends upon the altitude of the level of free convection (LFC), surface temperature (T) and surface mixing ratio (q). The box-and-whisker plot of LFC, T and q are drawn to select the most dependable parameter for the consistency of CINE in the prevalence of such thunderstorms. The skills of the parameters are evaluated through skill score analyses. The percentage error during validation with the observation of 2010 is estimated to be 0% for the range of CINE and 3.9% for CAPE.展开更多
Based on the lightning monitoring data, automatic and routine weather station observation data in spring （March-May） of 2013 of Sichuan Province, the corresponding relationship between the spatial distribution and t...Based on the lightning monitoring data, automatic and routine weather station observation data in spring （March-May） of 2013 of Sichuan Province, the corresponding relationship between the spatial distribution and the different regions, and the characteristics of atmospheric circulation and evolution of influence the sys- tem were analyzed and summarized. The results show that： the lightning and thunderstorm showed great regional differences in the spring of 2013 in Sichuan Province and the thunderstorm activity period was not the same in different areas. Because of the change of atmospheric circulation, the influence system from March to May corresponding to the thunderstorms in Sichuan tended to be volatile, also.展开更多
The observation, in the past, that a thunderstorm perturbed the transmissions of an old vacuum tubes radio with noise discharges in correspondence with lightnings, suggested the possibility of radio-acoustic study of ...The observation, in the past, that a thunderstorm perturbed the transmissions of an old vacuum tubes radio with noise discharges in correspondence with lightnings, suggested the possibility of radio-acoustic study of thunderstorms. The noise discharges appeared to convey not only information about lightnings, but also about any other thunderstorm electromagnetic phenomena generating noise discharges. The low-cost instrumentation involved in the radio-acoustic study, comprised a radio Telefunken mod. T33B, a 15 m long indoor wire antenna, a mobile telephone Samsung Galaxy S20 FE 5G provided with the recorder App Enregistreur vocal, a computer HP Pavillion dv5-1254eg and the s/w audio analyser Audacity. A first thunderstorm on 20 June 2023 and a second thunderstorm on 22 June 2023, both above Munich, were radio-acoustic studied. The second thunderstorm was more active than the first and released much more energy.展开更多
By dint of natural orthogonal function(EOF) decomposition,correlation and trend analysis methods,the temporal and spatial variation characteristics of thunderstorms in recent 46 years in Henan Province were analyzed.T...By dint of natural orthogonal function(EOF) decomposition,correlation and trend analysis methods,the temporal and spatial variation characteristics of thunderstorms in recent 46 years in Henan Province were analyzed.The result showed that the thunderstorms in Henan Province decreased gradually from the northwest region to the southeast region and the frequency of thunderstorms in the southeast area was relatively high.The thunderstorm intensity area was in its horizontal distribution.Thunderstorms acted relative actively in 60s and tended to dwindle in the end of 80s.While in recent years,the thunderstorms tended to increase and started act frequently.Since March to August in every year,thunderstorms multiplied in each region and decreased after September.The period between 16:00 to 20:00 was the high peak hours of thunderstorms every year.Thunderstorms distribution in Henan Province had pretty good consistence,increasing and decreasing at the same time.The annual variation of thunderstorms showed an unobvious decreasing tendency.展开更多
Three summer thunderstorms in the eastern region of China were analyzed in detail using multiple data, including Doppler radar, lightning location network, TRMM （Tropical Rainfall Measuring Mission）, MT- SAT （Multi...Three summer thunderstorms in the eastern region of China were analyzed in detail using multiple data, including Doppler radar, lightning location network, TRMM （Tropical Rainfall Measuring Mission）, MT- SAT （Multi-Function Transport Satellite） images, NCEP （National Centers for Environmental Prediction） Reanalysis, and radiosonde. Two of the three storms were sprite-producing and the other was non-sprite- producing. The two sprite-producing storms occurred on 1 2 August and 2~28 July 2007, producing 16 and one sprite, respectively. The non-sprite-producing storm occurred on 29-30 July 2007. The major ob- jective of the study was to try to find possible differences between sprite-producing and non-sprite producing storms using the multiple datasets. The results showed that the convection in the 1-2 August storm was the strongest compared with the other storms, and it produced the largest number of sprites. Precipitation ice, cloud ice and cloud water content in the convective regions in the 1-2 August storm were larger than in the other two storms, but the opposite was true in the weak convective regions. The storm microphysical prop- erties along lines through parent CG （cloud-to-ground lightning） locations showed no special characteristics related to sprites. The flash rate evolution in the 1-2 August storm provided additional confirmation that major sprite activity coincides with a rapid decrease in the negative CG flash rate. However, the evolution curve of the CG flash rate was erratic in the sprite-producing storm on 27-28 July, which was significantly different from that in the 1 2 August storm. The average positive CG peak current in sprite-producing storms was larger than that in the non-sprite-producing one.展开更多
The Tibetan Plateau, with an average altitude above 4000 m, is the highest and largest plateau in the world. The frequency of thunderstorms in this region is extremely high. Many indices are used in operational foreca...The Tibetan Plateau, with an average altitude above 4000 m, is the highest and largest plateau in the world. The frequency of thunderstorms in this region is extremely high. Many indices are used in operational forecasting to assess the stability of the atmosphere and predict the probability of severe thunderstorm development. One of the disadvantages of many of these indices is that they are mainly based on observations from plains. However, considering the Plateau＇s high elevation, most convective parameters cannot be applied directly, or their application is ineffective. The pre-convective environment on thunderstorm days in this region is investigated based on sounding data obtained throughout a five-year period（2006–10）.Thunderstorms occur over the Tibetan Plateau under conditions that differ strikingly from those in plains. On this basis,stability indices, such as the Showalter index（including SI and SICCL）, and the K index are improved to better assess the thunderstorm environments on the Plateau. Verification parameters, such as the true-skill statistic（TSS） and Heidke skill score（HSS）, are adopted to evaluate the optimal thresholds and relative forecast skill for each modified index. Lastly, the modified indices are verified with a two-year independent dataset（2011–12）, showing satisfactory results for the modified indices. For determining whether or not a thunderstorm day is likely to occur, we recommend the modified SICCLindex.展开更多
The electrical characteristics of thunderstorms in three different altitude regions of the Chinese inland plateau have been analyzed in this paper. The results show, according to the polarity of the surface electric ...The electrical characteristics of thunderstorms in three different altitude regions of the Chinese inland plateau have been analyzed in this paper. The results show, according to the polarity of the surface electric （E） field, that the thunderstorms can be divided into two categories in the study regions： one showing the normal tripole electrical charge structure （normal-type）, and the other showing the special tripole charge structure with a larger-than-usual lower positive charge center （LPCC） at the base of thunderstorm （special-type）, where the induced surface E field is controlled by the LPCC when a thunderstorm is overhead. We find that the two types of thunderstorms have different occurrences in different regions, and the percentage of special-type thunderstorms increases with the altitude. On the whole, the flash rate of thunderstorms is quite low, and the mean value is about 1-3 fl/min, while the flash rate of special-type is slightly greater than that of the normal-type thunderstorm. The statistical results of cloud-to-ground flash （CG） numbers indicate that the ratio of ＋CG flash increases with the altitude, with the value about 14.7 percent through 25.4 percent.展开更多
The influences of large areas of semi-unbounded cold water surface on the evolution, propagation and precipitation production of thunderstorms are simulated by using a fully elastic three-dimensional numerical hailsto...The influences of large areas of semi-unbounded cold water surface on the evolution, propagation and precipitation production of thunderstorms are simulated by using a fully elastic three-dimensional numerical hailstorm model. Real sounding profiles for temperature, humidity and wind are employed. The model has successfully simulated the significant modification of the propagation path of thunderstorms near the cold water area. The path change can be either' along-bank' or' toward-bank', depending on the position of the storm system relative to convergence zone of the water-land circulation. The simulations also show that thunderstorms developing or propagating within the convergence zone of local circulation will be intensified and produce much heavier hail, whereas those over cold water surface or the air that has been cooled by the water will be strongly inhibited.The influence of the cold water surface on thunderstorm characters is largely dependent upon the direction and intensity of the low-level wind.展开更多
Based on daily data of thunderstorms during 1967 -2012 from the national meteorological station in Doumen District of Zhuhai City, the climatic characteristics of thunderstorms in Doumen District were analyzed using c...Based on daily data of thunderstorms during 1967 -2012 from the national meteorological station in Doumen District of Zhuhai City, the climatic characteristics of thunderstorms in Doumen District were analyzed using climate tendency rate, sliding t test, trend analysis and experience frequency, The results showed that annual thunderstorm days in Doumen District showed a decreasing trend in recent 46 years; thunderstorms appeared in the whole year; monthly thunderstorm days had two peaks; thunderstorms occurred frequently in summer, especially in August, while thunderstorm days were the least in winter; annual thunderstorm days in Doumen District declined sharply in 1984; most thunderstorms began from middle February to late March and ended from late September to middle November; thunderstorms in Doumen District lasted for a long term, and there was a great change in thunderstorm duration in different years.展开更多
[Objective] The study aimed to discuss the distribution characteristics of thunderstorms in Xuzhou City. [Method] Based on thunder- storm observation data during 1978 -2008 provided by Jiuli Mountain station, beginnin...[Objective] The study aimed to discuss the distribution characteristics of thunderstorms in Xuzhou City. [Method] Based on thunder- storm observation data during 1978 -2008 provided by Jiuli Mountain station, beginning and ending months, days, duration, frequency, hours and direction of thunderstorms in Xuzhou were analyzed. [ Result] From 1978 to 2008, there were obvious annual variations in thunderstorm days in Xuzhou City. Thunderstorm days were more in July and August compared with other months, while there were no thunderstorms in January and De- comber. Thunderstorms began earliest in February and ended latest in November, with a long span. The longest duration of thunderstorms reached 259 d, accounting for 71% of total days of a year. The maximum frequency of thunderstorms （64） appeared in 1995, and the maximum hours of thunderstorms （4 048 h） appeared in 2003. Thunderstorms occurred most frequently in the southwest, followed by SE and NW. [ Conclusion] The research could provide scientific references for the prevention and control of lightning strokes in Xuzhou in future.展开更多
Based on the 1951-2007 thunderstorms in Jiangsu,a study is conducted for their climate trends,periodicity,spatiotemporal patterns,and the distributions of the first and last days of the thunderstorms at different guar...Based on the 1951-2007 thunderstorms in Jiangsu,a study is conducted for their climate trends,periodicity,spatiotemporal patterns,and the distributions of the first and last days of the thunderstorms at different guarantee rates (GRs) using climate tendency rate,wavelet analysis,and GR for diagnosis.Results suggest that the inter-annual number of thunderstorm days (TSDs) exhibits a decreasing trend in this province.The trend is displayed mainly in the decreasing TSD number in summer and autumn except in spring,when the variation is not significant in the study period.In this province,the TSD number declines by ～2 days per 10 years.On an inter-annual basis,the pronounced positive departures of the number take place chiefly in the early 1960s,the late 1960s to the early-mid-1970s,the late 1980s,and the late 1990s compared with the negative anomalies dominant in the late 1970s to the mid-1980s,the mid-to-late-1990s,and the late 1990s to 2007.There are vast differences in the initial and ending days at diverse GRs in different areas of the province.At 50% GR,the earliest (last) days occur from mid-March to early April (early to late September) while at 80% GR,the initial (last) days are from late March to early May (early to late October).For the distribution of periods,the periods >8-10 years are relatively stable for the entire province.Based on 1951-2007 period analysis,the region north (south) of the Huaihe River experiences TSDs less (more) than normal days in recent years.展开更多
Thunderstorms are severe convective weather systems generating lightning,which can lead to various catastrophic weather when a large amount of lightning is produced.In the past decade,high spatiotemporal resolution li...Thunderstorms are severe convective weather systems generating lightning,which can lead to various catastrophic weather when a large amount of lightning is produced.In the past decade,high spatiotemporal resolution lightning detection technology has been developed,which has laid a solid foundation for investigating the propagation and development mechanism of lightning as well as associated physical effects.Based on the Doppler dual polarization weather radar and high-resolution numerical models,thunderstorm dynamics,microphysics,electrical processes,and their interactions have been well investigated,and some new insights into the thunderstorm charge distribution and its relation to the thunderstorm structure have been obtained.All these have promoted the lightning forecasting and lightning data assimilation.This paper reviews the recent research progress in detection,mechanism,and forecasting of thunderstorms and lightning in China in the last decade from four aspects:1)high-resolution three-dimensional(3D)lightning mapping technology and application,2)lightning in different thunderstorms and its relationship with cloud dynamics and microphysics,3)observation and simulation of lightning charge structure in thunderstorms,and 4)lightning prediction and lightning data assimilation for thunderstorm forecasting.Major challenges and the cuttingedge research directions in lightning and thunderstorms studies are also highlighted.展开更多
With data mainly from Guangzhou mesonet Automatic Weather Stations(AWS),Guangzhou Doppler Radar and satellite TBB data,characteristics and evolution of the urban heat island(UHI) over Guang-zhou City were analyzed in ...With data mainly from Guangzhou mesonet Automatic Weather Stations(AWS),Guangzhou Doppler Radar and satellite TBB data,characteristics and evolution of the urban heat island(UHI) over Guang-zhou City were analyzed in a tropical cyclone affected situation for early August 2005.In particular,two thunderstorms occurring during this period respectively at the night of 4 August and in the afternoon of 7 August were investigated to study the relationships between the development of thunderstorms and the UHI.Results showed that two thunderstorms were associated with the UHI effects.UHI induced local air convergence and initiated the thunderstorm convections.Both cases showed a general agreement in time and space for the locations of maximum UHI,convergence,convection,and pre-cipitation.Convection was found to be more favorable to developing in time periods and locations with stronger intensity of UHI.Analysis also showed that,due to the urban effects,both thunderstorms got strengthened when moving over Guangzhou City,with maximum radar echoes observed right over the urban area and precipitation located within the city.All these features reveal that two thunderstorms were urban-induced storms.展开更多
The comprehensive observations on lightning discharges were conducted in Naqu area of Qinghai-Tibet Plateau in summer of 2002. The electric structures of thunderstorms and the characteristics of lightning discharges a...The comprehensive observations on lightning discharges were conducted in Naqu area of Qinghai-Tibet Plateau in summer of 2002. The electric structures of thunderstorms and the characteristics of lightning discharges at initial stage were analyzed by using the observation data. The results show that most of intracloud (IC) lightning flashes were polarities inverted in thunderstorms with tripole electric charge structure and occurred between negative charge region located in the middle of the thunderstorm and positive charge region located at the bottom of the thunderstorm. The radiation characteristics of discharge processes in cloud with longer lasting time involved in Cloud-to-Ground (CG) lightning flashes were similar to that of IC discharges.A lot of radiation pulses were produced in these discharge processes. Because the IC discharges took place at the bottom of thundercloud and were near the ground, they may produce more serious damage to equipment on the ground therefore should not be neglected in lightning protection.展开更多
The lightning-induced-damages in the mid-latitude regions are usually caused during severe thunderstorms. But the discharge parameters of natural lightning are difficult to be measured. Five lightning flashes have bee...The lightning-induced-damages in the mid-latitude regions are usually caused during severe thunderstorms. But the discharge parameters of natural lightning are difficult to be measured. Five lightning flashes have been artificially triggered with the rocket-wire technique during the passage of two severe thunderstorms. The discharge current and close electric field of return stroke in artificially triggered lightning have been obtained in microsecond time resolution by using current measuring systems and electric field change sensors. The results show that the five triggered lightning flashes include 1 to 10 return strokes, and the average return stroke current is 11.9 kA with a maximum of 21.0 kA and a minimum of 6.6 kA, similar to the subsequent return strokes in natural lightning. The half peak width of the current waveform is 39 us, which is much larger than the usual result. The peak current of stroke I_p(kA) and the neutralized charge Q(C) has a relationship of I_p = 18.5Q^(0.65). The radiation field of return stroke is 5.9 kV ? m^(-1) and 0.39 kV ? m^(-1) at 60 m and 550 m, respectively. The radiation field decreases as r^(-1.119) with increase of horizontal distance r from the discharge channel. Based on the well-accepted transmission line model, the speed of return stroke is estimated to be about 1.4 × 10~8m·s^(-1), with a variation range of (1.1-1.6)×10~8m·s^(-1). Because of the similarities of the triggered lightning and natural lightning, the results in this article can be used in the protection design of natural lightning.展开更多
The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan regio...The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model.展开更多
The purpose of this study was to understand the reasons why frequent positive cloud-to-ground(+CG) flashes occur in severe thunderstorms. A three-dimensional dynamics-electrification coupled model was used to simulate...The purpose of this study was to understand the reasons why frequent positive cloud-to-ground(+CG) flashes occur in severe thunderstorms. A three-dimensional dynamics-electrification coupled model was used to simulate a severe thunderstorm to permit analysis of the conditions that might easily cause +CG flashes. The results showed that strong updrafts play an important role in the occurrence of intracloud flashes. However, frequent +CG flashes require not only strong updrafts but also strong downdrafts in the lower cloud region, conditions that correspond to the later phase of the mature stage and the period of the heaviest solid precipitation of a thunderstorm. During this stage, strong updrafts elevated each charge area in the updraft region to a higher level, which resulted in an inverted tripole charge structure. A wide mid-level region of strong positive charge caused largely by positively charged graupel, presented in the middle of the updraft region because of a non-inductive ice-ice collisional charging mechanism. The charge structure in the downdraft region was consistently more complex and revealed several vertically stacked charge regions, alternating in polarity. Much of the graupel/hail outside the updrafts was lowered to cloud-base by strong downdrafts. In this area, the graupel/hail was charged negatively because of the transportation of negatively charged graupel/hail from higher regions of negative charge in the updrafts, and via the inductive charging mechanism of collisions between graupel/hail and cloud droplets at the bottom of the cloud. Consequently, a large region of negative charge formed near the ground. This meant that +CG flashes were initiated more easily in the lower inverted dipole, i.e., the middle region of positive charge and lower region of negative charge. Frequent +CG flashes began almost synchronously with dramatic increases in the storm updrafts, hail volume, and total flash rate. Therefore, the occurrence of +CG flashes appears a good indicator of storm intensification and it could have some use as a predictor of severe weather in the form of hail.展开更多
Here we report characteristics of more than 100 cases of Narrow Bipolar Events(NBEs)occurred during two thunderstorms on the basis of our analysis of the dataset collected by a GPS based three-station time of arrival(...Here we report characteristics of more than 100 cases of Narrow Bipolar Events(NBEs)occurred during two thunderstorms on the basis of our analysis of the dataset collected by a GPS based three-station time of arrival(TOA)lightning location system deployed in Northeast China during the summer of 2010.All of the NBEs were of positive polarity and the amplitude of VLF/LF initial pulse of NBE was comparable to that of return strokes.The waveform characteristics of 166 NBEs that occurred within 150 km were consistent with the results of other reports.The average value of initial peak width of the bipolar pulse is 7.8±1.5 μs,full width at half maximum is 4.6±1.0 μs,and the ratio of initial peak amplitude to overshoot peak is 2.1±0.6.The inferred source height of NBEs occurred in two thunderstorms averaged 9.6 and 7.4 km above mean sea level,whereas the corresponding virtual ionosphere heights at two different times were 89 and 78 km,respectively.In NBEproducing thunderstorms,NBEs tended to burst during the active stage of normal lightning;nevertheless,no determinate quantitative relations could be established between them.In Storm 0711,NBEs were inclined to cluster at the proximity of particular convective cores with high radar reflectivity,and NBEs tended to move consistently at the front area of those NBE-producing convective cores during the evolution of thunderstorm.展开更多
Terrestrial gamma-ray flashes(TGFs)are high-energy emissions in thunderstorms that were discovered first by satellite-based and then by ground-based gamma-ray detectors with photon energy up to tens of Me V.TGFs are a...Terrestrial gamma-ray flashes(TGFs)are high-energy emissions in thunderstorms that were discovered first by satellite-based and then by ground-based gamma-ray detectors with photon energy up to tens of Me V.TGFs are a natural highenergy phenomenon associated with lightning discharges that frequently occur during thunderstorms.However,their production mechanisms and associated processes are still unclear.TGF studies have already been a research spotlight in the atmospheric electricity and high-energy atmosphere research areas.In this paper,we review recent research progresses on TGF studies in the past decade,including TGF detection,the relationship between TGFs and lightning processes,and thunderstorm activities.Several unsolved important scientific questions are discussed.Results suggest that upward TGFs observed by satellite-based detectors are closely connected with the development of in-cloud upward negative leaders.They are usually generated in milliseconds of the initiation of upward negative leaders and may produce a kind of distinct radio emissions because of the generation and propagation of huge amounts of high-energy electrons.By contrast,its counterpart,i.e.,downward TGFs observed by ground-based gamma-ray detectors,is associated with different types of lightning processes,such as downward negative or upward positive leaders,the initial continuing current stage of rocket-triggered lightning flashes return stroke processes.Because of limited observations,how these downward TGFs are generated is still unclear.Benefiting from the development of state-of-the-art instruments with high temporal and spatial resolutions,new insights into the processes and mechanisms of TGFs will be achieved with coordinated observations from satellite-based and ground-based measurements.展开更多
基金funded by the Natural Science Foundation of China(Grant No.U2342215)Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province(Grant No.SCSF202302)。
文摘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℃ 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℃ 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.
文摘Thunderstorms of pre-monsoon season (April – May) over Kolkata (22° 32’N, 88° 20’E), India are invariably accompanied with lightning flashes, high wind gusts, torrential rainfall, occasional hail and tornadoes which significantly affect the life and property on the ground and aviation aloft. The societal and economic impact due to such storms made accurate prediction of the weather phenomenon a serious concern for the meteorologists of India. The initiation of such storms requires sufficient moisture in lower troposphere, high surface temperature, conditional instability and a source of lift to initiate the convection. Convective available potential energy (CAPE) is a measure of the energy realized when conditional instability is released. It plays an important role in meso-scale convective systems. Convective inhibition energy (CINE) on the other hand acts as a possible barrier to the release of convection even in the presence of high value of CAPE. The main idea of the present study is to see whether a consistent quantitative range of CAPE and CINE can be identified for the prevalence of such thunderstorms that may aid in operational forecast. A statistical – fuzzy coupled method is implemented for the purpose. The result reveals that a definite range of CINE within 0 – 150 Jkg-1 is reasonably pertinent whereas no such range of CAPE depicts any consistency for the occurrence of severe thunderstorms over Kolkata. The measure of CINE mainly depends upon the altitude of the level of free convection (LFC), surface temperature (T) and surface mixing ratio (q). The box-and-whisker plot of LFC, T and q are drawn to select the most dependable parameter for the consistency of CINE in the prevalence of such thunderstorms. The skills of the parameters are evaluated through skill score analyses. The percentage error during validation with the observation of 2010 is estimated to be 0% for the range of CINE and 3.9% for CAPE.
文摘Based on the lightning monitoring data, automatic and routine weather station observation data in spring （March-May） of 2013 of Sichuan Province, the corresponding relationship between the spatial distribution and the different regions, and the characteristics of atmospheric circulation and evolution of influence the sys- tem were analyzed and summarized. The results show that： the lightning and thunderstorm showed great regional differences in the spring of 2013 in Sichuan Province and the thunderstorm activity period was not the same in different areas. Because of the change of atmospheric circulation, the influence system from March to May corresponding to the thunderstorms in Sichuan tended to be volatile, also.
文摘The observation, in the past, that a thunderstorm perturbed the transmissions of an old vacuum tubes radio with noise discharges in correspondence with lightnings, suggested the possibility of radio-acoustic study of thunderstorms. The noise discharges appeared to convey not only information about lightnings, but also about any other thunderstorm electromagnetic phenomena generating noise discharges. The low-cost instrumentation involved in the radio-acoustic study, comprised a radio Telefunken mod. T33B, a 15 m long indoor wire antenna, a mobile telephone Samsung Galaxy S20 FE 5G provided with the recorder App Enregistreur vocal, a computer HP Pavillion dv5-1254eg and the s/w audio analyser Audacity. A first thunderstorm on 20 June 2023 and a second thunderstorm on 22 June 2023, both above Munich, were radio-acoustic studied. The second thunderstorm was more active than the first and released much more energy.
基金Supported by Scientific Research Special Fund for Public Welfare Industry (GYHY 200806014)Nanjing University of Information Science & Technology Program (E30JG0730)
文摘By dint of natural orthogonal function(EOF) decomposition,correlation and trend analysis methods,the temporal and spatial variation characteristics of thunderstorms in recent 46 years in Henan Province were analyzed.The result showed that the thunderstorms in Henan Province decreased gradually from the northwest region to the southeast region and the frequency of thunderstorms in the southeast area was relatively high.The thunderstorm intensity area was in its horizontal distribution.Thunderstorms acted relative actively in 60s and tended to dwindle in the end of 80s.While in recent years,the thunderstorms tended to increase and started act frequently.Since March to August in every year,thunderstorms multiplied in each region and decreased after September.The period between 16:00 to 20:00 was the high peak hours of thunderstorms every year.Thunderstorms distribution in Henan Province had pretty good consistence,increasing and decreasing at the same time.The annual variation of thunderstorms showed an unobvious decreasing tendency.
基金supported jointly by Strategic Priority Research Program on Space Science(Grant No.XDA04072400)Project Supported by the Specialized Research Fund for State Key Laboratories,Youth Innovation Promotion Association,CAS,National Basic Research Program of China(973 Program,Grant No.2010CB428602)+2 种基金the Special Fund for Public Welfare Industry(GYHY201006005-07)National Natural Science Foundation of China(Grant Nos.41374153,40930949,40804028)Beijing Natural Science Foundation
文摘Three summer thunderstorms in the eastern region of China were analyzed in detail using multiple data, including Doppler radar, lightning location network, TRMM （Tropical Rainfall Measuring Mission）, MT- SAT （Multi-Function Transport Satellite） images, NCEP （National Centers for Environmental Prediction） Reanalysis, and radiosonde. Two of the three storms were sprite-producing and the other was non-sprite- producing. The two sprite-producing storms occurred on 1 2 August and 2~28 July 2007, producing 16 and one sprite, respectively. The non-sprite-producing storm occurred on 29-30 July 2007. The major ob- jective of the study was to try to find possible differences between sprite-producing and non-sprite producing storms using the multiple datasets. The results showed that the convection in the 1-2 August storm was the strongest compared with the other storms, and it produced the largest number of sprites. Precipitation ice, cloud ice and cloud water content in the convective regions in the 1-2 August storm were larger than in the other two storms, but the opposite was true in the weak convective regions. The storm microphysical prop- erties along lines through parent CG （cloud-to-ground lightning） locations showed no special characteristics related to sprites. The flash rate evolution in the 1-2 August storm provided additional confirmation that major sprite activity coincides with a rapid decrease in the negative CG flash rate. However, the evolution curve of the CG flash rate was erratic in the sprite-producing storm on 27-28 July, which was significantly different from that in the 1 2 August storm. The average positive CG peak current in sprite-producing storms was larger than that in the non-sprite-producing one.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41275128, 41375063 and 41206163)the Chengdu Institute of Plateau Meteorology Foundation
文摘The Tibetan Plateau, with an average altitude above 4000 m, is the highest and largest plateau in the world. The frequency of thunderstorms in this region is extremely high. Many indices are used in operational forecasting to assess the stability of the atmosphere and predict the probability of severe thunderstorm development. One of the disadvantages of many of these indices is that they are mainly based on observations from plains. However, considering the Plateau＇s high elevation, most convective parameters cannot be applied directly, or their application is ineffective. The pre-convective environment on thunderstorm days in this region is investigated based on sounding data obtained throughout a five-year period（2006–10）.Thunderstorms occur over the Tibetan Plateau under conditions that differ strikingly from those in plains. On this basis,stability indices, such as the Showalter index（including SI and SICCL）, and the K index are improved to better assess the thunderstorm environments on the Plateau. Verification parameters, such as the true-skill statistic（TSS） and Heidke skill score（HSS）, are adopted to evaluate the optimal thresholds and relative forecast skill for each modified index. Lastly, the modified indices are verified with a two-year independent dataset（2011–12）, showing satisfactory results for the modified indices. For determining whether or not a thunderstorm day is likely to occur, we recommend the modified SICCLindex.
基金supported by National Natural Science Foundation of China (Grant No. 40905001, 40775004)the Main Direction Program of the Knowledge Innovation of Chinese Academy of Sciences (Grant No.KZCX2-YW-206)
文摘The electrical characteristics of thunderstorms in three different altitude regions of the Chinese inland plateau have been analyzed in this paper. The results show, according to the polarity of the surface electric （E） field, that the thunderstorms can be divided into two categories in the study regions： one showing the normal tripole electrical charge structure （normal-type）, and the other showing the special tripole charge structure with a larger-than-usual lower positive charge center （LPCC） at the base of thunderstorm （special-type）, where the induced surface E field is controlled by the LPCC when a thunderstorm is overhead. We find that the two types of thunderstorms have different occurrences in different regions, and the percentage of special-type thunderstorms increases with the altitude. On the whole, the flash rate of thunderstorms is quite low, and the mean value is about 1-3 fl/min, while the flash rate of special-type is slightly greater than that of the normal-type thunderstorm. The statistical results of cloud-to-ground flash （CG） numbers indicate that the ratio of ＋CG flash increases with the altitude, with the value about 14.7 percent through 25.4 percent.
基金This work is supported by LASG, IAP, Chinese Academy of Sciences.
文摘The influences of large areas of semi-unbounded cold water surface on the evolution, propagation and precipitation production of thunderstorms are simulated by using a fully elastic three-dimensional numerical hailstorm model. Real sounding profiles for temperature, humidity and wind are employed. The model has successfully simulated the significant modification of the propagation path of thunderstorms near the cold water area. The path change can be either' along-bank' or' toward-bank', depending on the position of the storm system relative to convergence zone of the water-land circulation. The simulations also show that thunderstorms developing or propagating within the convergence zone of local circulation will be intensified and produce much heavier hail, whereas those over cold water surface or the air that has been cooled by the water will be strongly inhibited.The influence of the cold water surface on thunderstorm characters is largely dependent upon the direction and intensity of the low-level wind.
文摘Based on daily data of thunderstorms during 1967 -2012 from the national meteorological station in Doumen District of Zhuhai City, the climatic characteristics of thunderstorms in Doumen District were analyzed using climate tendency rate, sliding t test, trend analysis and experience frequency, The results showed that annual thunderstorm days in Doumen District showed a decreasing trend in recent 46 years; thunderstorms appeared in the whole year; monthly thunderstorm days had two peaks; thunderstorms occurred frequently in summer, especially in August, while thunderstorm days were the least in winter; annual thunderstorm days in Doumen District declined sharply in 1984; most thunderstorms began from middle February to late March and ended from late September to middle November; thunderstorms in Doumen District lasted for a long term, and there was a great change in thunderstorm duration in different years.
文摘[Objective] The study aimed to discuss the distribution characteristics of thunderstorms in Xuzhou City. [Method] Based on thunder- storm observation data during 1978 -2008 provided by Jiuli Mountain station, beginning and ending months, days, duration, frequency, hours and direction of thunderstorms in Xuzhou were analyzed. [ Result] From 1978 to 2008, there were obvious annual variations in thunderstorm days in Xuzhou City. Thunderstorm days were more in July and August compared with other months, while there were no thunderstorms in January and De- comber. Thunderstorms began earliest in February and ended latest in November, with a long span. The longest duration of thunderstorms reached 259 d, accounting for 71% of total days of a year. The maximum frequency of thunderstorms （64） appeared in 1995, and the maximum hours of thunderstorms （4 048 h） appeared in 2003. Thunderstorms occurred most frequently in the southwest, followed by SE and NW. [ Conclusion] The research could provide scientific references for the prevention and control of lightning strokes in Xuzhou in future.
基金Social Development Program of Jiangsu Science and Technology (BS2007088)
文摘Based on the 1951-2007 thunderstorms in Jiangsu,a study is conducted for their climate trends,periodicity,spatiotemporal patterns,and the distributions of the first and last days of the thunderstorms at different guarantee rates (GRs) using climate tendency rate,wavelet analysis,and GR for diagnosis.Results suggest that the inter-annual number of thunderstorm days (TSDs) exhibits a decreasing trend in this province.The trend is displayed mainly in the decreasing TSD number in summer and autumn except in spring,when the variation is not significant in the study period.In this province,the TSD number declines by ～2 days per 10 years.On an inter-annual basis,the pronounced positive departures of the number take place chiefly in the early 1960s,the late 1960s to the early-mid-1970s,the late 1980s,and the late 1990s compared with the negative anomalies dominant in the late 1970s to the mid-1980s,the mid-to-late-1990s,and the late 1990s to 2007.There are vast differences in the initial and ending days at diverse GRs in different areas of the province.At 50% GR,the earliest (last) days occur from mid-March to early April (early to late September) while at 80% GR,the initial (last) days are from late March to early May (early to late October).For the distribution of periods,the periods >8-10 years are relatively stable for the entire province.Based on 1951-2007 period analysis,the region north (south) of the Huaihe River experiences TSDs less (more) than normal days in recent years.
基金Supported by the National Natural Science Foundation of China(42230609)Chinese Academy of Sciences Strategic Leading Science and Technology Project(XDB0760300)。
文摘Thunderstorms are severe convective weather systems generating lightning,which can lead to various catastrophic weather when a large amount of lightning is produced.In the past decade,high spatiotemporal resolution lightning detection technology has been developed,which has laid a solid foundation for investigating the propagation and development mechanism of lightning as well as associated physical effects.Based on the Doppler dual polarization weather radar and high-resolution numerical models,thunderstorm dynamics,microphysics,electrical processes,and their interactions have been well investigated,and some new insights into the thunderstorm charge distribution and its relation to the thunderstorm structure have been obtained.All these have promoted the lightning forecasting and lightning data assimilation.This paper reviews the recent research progress in detection,mechanism,and forecasting of thunderstorms and lightning in China in the last decade from four aspects:1)high-resolution three-dimensional(3D)lightning mapping technology and application,2)lightning in different thunderstorms and its relationship with cloud dynamics and microphysics,3)observation and simulation of lightning charge structure in thunderstorms,and 4)lightning prediction and lightning data assimilation for thunderstorm forecasting.Major challenges and the cuttingedge research directions in lightning and thunderstorms studies are also highlighted.
基金Supported jointly by the R&D Infrastructure and Facility Developemnt Program (2003DIB4J145)from the Ministry of Science and Technology of China, Urban Meteorological Science Research Fund (UMRF200504)the Open Research Fund from the State Key Laboratory of Severe Weather,Chinese Academy of Mete-orological Sciences
文摘With data mainly from Guangzhou mesonet Automatic Weather Stations(AWS),Guangzhou Doppler Radar and satellite TBB data,characteristics and evolution of the urban heat island(UHI) over Guang-zhou City were analyzed in a tropical cyclone affected situation for early August 2005.In particular,two thunderstorms occurring during this period respectively at the night of 4 August and in the afternoon of 7 August were investigated to study the relationships between the development of thunderstorms and the UHI.Results showed that two thunderstorms were associated with the UHI effects.UHI induced local air convergence and initiated the thunderstorm convections.Both cases showed a general agreement in time and space for the locations of maximum UHI,convergence,convection,and pre-cipitation.Convection was found to be more favorable to developing in time periods and locations with stronger intensity of UHI.Analysis also showed that,due to the urban effects,both thunderstorms got strengthened when moving over Guangzhou City,with maximum radar echoes observed right over the urban area and precipitation located within the city.All these features reveal that two thunderstorms were urban-induced storms.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX1-SW-04)the National Natural Science Foundation of China(Grant No.40375004).
文摘The comprehensive observations on lightning discharges were conducted in Naqu area of Qinghai-Tibet Plateau in summer of 2002. The electric structures of thunderstorms and the characteristics of lightning discharges at initial stage were analyzed by using the observation data. The results show that most of intracloud (IC) lightning flashes were polarities inverted in thunderstorms with tripole electric charge structure and occurred between negative charge region located in the middle of the thunderstorm and positive charge region located at the bottom of the thunderstorm. The radiation characteristics of discharge processes in cloud with longer lasting time involved in Cloud-to-Ground (CG) lightning flashes were similar to that of IC discharges.A lot of radiation pulses were produced in these discharge processes. Because the IC discharges took place at the bottom of thundercloud and were near the ground, they may produce more serious damage to equipment on the ground therefore should not be neglected in lightning protection.
基金the National Natural Science Foundation of China (Grant Nos. 40135010 and 40325013) the Ministry of Science and Technology of China (Grant No. 2004DEA71070)
文摘The lightning-induced-damages in the mid-latitude regions are usually caused during severe thunderstorms. But the discharge parameters of natural lightning are difficult to be measured. Five lightning flashes have been artificially triggered with the rocket-wire technique during the passage of two severe thunderstorms. The discharge current and close electric field of return stroke in artificially triggered lightning have been obtained in microsecond time resolution by using current measuring systems and electric field change sensors. The results show that the five triggered lightning flashes include 1 to 10 return strokes, and the average return stroke current is 11.9 kA with a maximum of 21.0 kA and a minimum of 6.6 kA, similar to the subsequent return strokes in natural lightning. The half peak width of the current waveform is 39 us, which is much larger than the usual result. The peak current of stroke I_p(kA) and the neutralized charge Q(C) has a relationship of I_p = 18.5Q^(0.65). The radiation field of return stroke is 5.9 kV ? m^(-1) and 0.39 kV ? m^(-1) at 60 m and 550 m, respectively. The radiation field decreases as r^(-1.119) with increase of horizontal distance r from the discharge channel. Based on the well-accepted transmission line model, the speed of return stroke is estimated to be about 1.4 × 10~8m·s^(-1), with a variation range of (1.1-1.6)×10~8m·s^(-1). Because of the similarities of the triggered lightning and natural lightning, the results in this article can be used in the protection design of natural lightning.
基金supported by the National Natural Science Foundation of China(Grant Nos.41630425,41671144074)the Key Research Program of Frontier Science,CAS(Grant No.QYZDJ-SSW-DQC007)the National Key Basic Research Program of China(Grant No.2014CB441401)。
文摘The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model.
基金supported by the National Key Basic Research Program of China (Grant No. 2014CB441403)the National Natural Science Foundation of China (Grant No. 41275008)+1 种基金R&D Special Fund for Public Welfare Industry (Grant No. GYHY201306069)Open Project of Key Laboratory of Meteorological Disaster of Ministry of Education (Grant No. KLME1004)
文摘The purpose of this study was to understand the reasons why frequent positive cloud-to-ground(+CG) flashes occur in severe thunderstorms. A three-dimensional dynamics-electrification coupled model was used to simulate a severe thunderstorm to permit analysis of the conditions that might easily cause +CG flashes. The results showed that strong updrafts play an important role in the occurrence of intracloud flashes. However, frequent +CG flashes require not only strong updrafts but also strong downdrafts in the lower cloud region, conditions that correspond to the later phase of the mature stage and the period of the heaviest solid precipitation of a thunderstorm. During this stage, strong updrafts elevated each charge area in the updraft region to a higher level, which resulted in an inverted tripole charge structure. A wide mid-level region of strong positive charge caused largely by positively charged graupel, presented in the middle of the updraft region because of a non-inductive ice-ice collisional charging mechanism. The charge structure in the downdraft region was consistently more complex and revealed several vertically stacked charge regions, alternating in polarity. Much of the graupel/hail outside the updrafts was lowered to cloud-base by strong downdrafts. In this area, the graupel/hail was charged negatively because of the transportation of negatively charged graupel/hail from higher regions of negative charge in the updrafts, and via the inductive charging mechanism of collisions between graupel/hail and cloud droplets at the bottom of the cloud. Consequently, a large region of negative charge formed near the ground. This meant that +CG flashes were initiated more easily in the lower inverted dipole, i.e., the middle region of positive charge and lower region of negative charge. Frequent +CG flashes began almost synchronously with dramatic increases in the storm updrafts, hail volume, and total flash rate. Therefore, the occurrence of +CG flashes appears a good indicator of storm intensification and it could have some use as a predictor of severe weather in the form of hail.
基金supported by the R&D Special Fund for Public Welfare Industry(Grant GYHY:(forestry) 200704027 and (meteorology) GYHY201006005)National Natural Science Foundation of China (Grant Nos. 41075001 and 40775003)
文摘Here we report characteristics of more than 100 cases of Narrow Bipolar Events(NBEs)occurred during two thunderstorms on the basis of our analysis of the dataset collected by a GPS based three-station time of arrival(TOA)lightning location system deployed in Northeast China during the summer of 2010.All of the NBEs were of positive polarity and the amplitude of VLF/LF initial pulse of NBE was comparable to that of return strokes.The waveform characteristics of 166 NBEs that occurred within 150 km were consistent with the results of other reports.The average value of initial peak width of the bipolar pulse is 7.8±1.5 μs,full width at half maximum is 4.6±1.0 μs,and the ratio of initial peak amplitude to overshoot peak is 2.1±0.6.The inferred source height of NBEs occurred in two thunderstorms averaged 9.6 and 7.4 km above mean sea level,whereas the corresponding virtual ionosphere heights at two different times were 89 and 78 km,respectively.In NBEproducing thunderstorms,NBEs tended to burst during the active stage of normal lightning;nevertheless,no determinate quantitative relations could be established between them.In Storm 0711,NBEs were inclined to cluster at the proximity of particular convective cores with high radar reflectivity,and NBEs tended to move consistently at the front area of those NBE-producing convective cores during the evolution of thunderstorm.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC1501500)the Basic Research Fund of the Chinese Academy of Meteorological Sciences(Grants Nos.2020R004&2021Z003)the Chinese Meridian Project and the International Partnership Program of Chinese Academy of Sciences(Grant No.183311KYSB20200003)。
文摘Terrestrial gamma-ray flashes(TGFs)are high-energy emissions in thunderstorms that were discovered first by satellite-based and then by ground-based gamma-ray detectors with photon energy up to tens of Me V.TGFs are a natural highenergy phenomenon associated with lightning discharges that frequently occur during thunderstorms.However,their production mechanisms and associated processes are still unclear.TGF studies have already been a research spotlight in the atmospheric electricity and high-energy atmosphere research areas.In this paper,we review recent research progresses on TGF studies in the past decade,including TGF detection,the relationship between TGFs and lightning processes,and thunderstorm activities.Several unsolved important scientific questions are discussed.Results suggest that upward TGFs observed by satellite-based detectors are closely connected with the development of in-cloud upward negative leaders.They are usually generated in milliseconds of the initiation of upward negative leaders and may produce a kind of distinct radio emissions because of the generation and propagation of huge amounts of high-energy electrons.By contrast,its counterpart,i.e.,downward TGFs observed by ground-based gamma-ray detectors,is associated with different types of lightning processes,such as downward negative or upward positive leaders,the initial continuing current stage of rocket-triggered lightning flashes return stroke processes.Because of limited observations,how these downward TGFs are generated is still unclear.Benefiting from the development of state-of-the-art instruments with high temporal and spatial resolutions,new insights into the processes and mechanisms of TGFs will be achieved with coordinated observations from satellite-based and ground-based measurements.
