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
Based on the cloud-to-ground（ CG） lightning flashes data and other related data from 1999 to 2016,the lightning risk zoning of Meizhou was conducted by using the analytic hierarchy process（ AHP） model. The model c...Based on the cloud-to-ground（ CG） lightning flashes data and other related data from 1999 to 2016,the lightning risk zoning of Meizhou was conducted by using the analytic hierarchy process（ AHP） model. The model considered the natural conditions,social economic conditions and other factors,and the main assessment factors were selected,containing ＂ flash density,lightning current intensity,annual thunderstorm days,lightning disaster frequency,construction area per capita and GDP per capita＂,in order to establish the evaluation model,and divide the level of risk. The results showed that the lightning risk in Meizhou area roughly had the trend of ＂ center higher than all-around,the south higher than the north,the west higher than the east＂. High-risk area was in the most region of Meijiang District and central region of Meixian District,and Wuhua County was next high-risk area. Xingning City and Fengshun County were medium risk areas,most of the other were low risk area. The result of regionalization was consistent with the actual situation,and the evaluation method was scientific and effective. Through the analysis of the lightning risk zoning,this paper could provide a scientific basis for the lightning protection and disaster reduction in the region in the future.展开更多
By using monitoring data of lightning locating system in Hebei during 1999- 2010 and lightning disaster data in Hebei during 2002- 2010,temporal-spatial distribution characteristics of ground flash and lightning disas...By using monitoring data of lightning locating system in Hebei during 1999- 2010 and lightning disaster data in Hebei during 2002- 2010,temporal-spatial distribution characteristics of ground flash and lightning disaster in Hebei Province were analyzed. Annual,monthly and daily changes of ground flash,lightning current intensity and ground flash density in Hebei were analyzed,and we compared ground flash with lightning disaster distribution.展开更多
The problems in calculating parameters of equivalent collection area,earth resistivity and lightning protection category as well as their effects on lightning disaster risk assessment were analyzed,and practical examp...The problems in calculating parameters of equivalent collection area,earth resistivity and lightning protection category as well as their effects on lightning disaster risk assessment were analyzed,and practical examples proved the effects of those differences on lightning protection identification,intercept efficiency calculation in evaluating lightning disaster risk. In the meantime,several new concepts,such as the height of buildings for lightning protection were defined,and a fixed radius value was set to the ground flash density for calculation,establishing the ground flash density formula to solve the problems in parameter calculation,which would be beneficial to promote the standardization of lightning disaster risk assessment.展开更多
Simultaneous observations for the total column densities of NO2,O3 and H2O were carried on using the portable Spectrometer (438-450 nm and 400-450 nm) and the visible Spectrometer (544.4-628 nm) during premonsoon thun...Simultaneous observations for the total column densities of NO2,O3 and H2O were carried on using the portable Spectrometer (438-450 nm and 400-450 nm) and the visible Spectrometer (544.4-628 nm) during premonsoon thunderstorms and embedded hail storm activity at Pune (18°32'N & 73°51'E),India.These observations confirm the fact that there is an increase in O3 and NO2 column densities during thunderstorms.The increase in O3 was observed following onset of thunderstorm,while the increase in NO2 was observed only after the thunder flashes occur.This implies that the production mechanisms for O3 and NO2 in thunderstorm are different.The observed column density of NO,value (1 to 3×1017molecules cm-2) during thunderstorm activity is 10 to 30 times higher than the value (1×10th molecules cm-2) of a normal day total column density.The spectrometric observations and observations of thunder flashes by electric field meter showed that 6.4×1025molecules/flash of NO2 are produced.The increased to-oil column density of ozone during thunderstorm period is 1.2 times higher than normal (clear) day ozone concentration.The multiple scattering in the clouds is estimated from H2O and O2 absorption bands in the visible spectral region Considering this effect the calculated amount of ozone added in the global atmosphere due to thunderstorm activity is 0.26 to 0 52 DU,and the annual production of ozone due to thunderstorm activity is of the order of 4.02×10 molecules/year The annual NO2 production may be of the order of 2.02×1035molecules/year.展开更多
During the pre-summer rainy season,heavy rainfall occurs frequently in South China.Based on polarimetric radar observations,the microphysical characteristics and processes of convective features associated with extrem...During the pre-summer rainy season,heavy rainfall occurs frequently in South China.Based on polarimetric radar observations,the microphysical characteristics and processes of convective features associated with extreme rainfall rates(ERCFs)are examined.In the regions with high ERCF occurrence frequency,sub-regional differences are found in the lightning flash rate(LFR)distributions.In the region with higher LFRs,the ERCFs have larger volumes of high reflectivity factor above the freezing level,corresponding to more active riming processes.In addition,these ERCFs are more organized and display larger spatial coverage,which may be related to the stronger low-level wind shear and higher terrain in the region.In the region with lower LFRs,the ERCFs have lower echo tops and lower-echo centroids.However,no clear differences of the most unstable convective available potential energy(MUCAPE)exist in the ERCFs in the regions with different LFR characteristics.Regardless of the LFRs,raindrop collisional coalescence is the main process for the growth of raindrops in the ERCFs.In the ERCFs within the region with lower LFRs,the main mechanism for the rapid increase of liquid water content with decreasing altitude below 4 km is through the warm-rain processes converting cloud drops to raindrops.However,in those with higher LFRs,the liquid water content generally decreases with decreasing altitude.展开更多
Based on the transmission line equations, this paper has developed computing formulas of current and voltage induced on the cable over the ground plane by Flash of Lightning Between Clouds (FBC), and estimated current...Based on the transmission line equations, this paper has developed computing formulas of current and voltage induced on the cable over the ground plane by Flash of Lightning Between Clouds (FBC), and estimated current and voltage on the cable of metal shielded sheath and analyzed the results.展开更多
In this paper the statistical analysis is carried out on the correlation between lightning strokes and atmospheric stratification factors.It is shown that the total number of strokes in lightning process is mainly dec...In this paper the statistical analysis is carried out on the correlation between lightning strokes and atmospheric stratification factors.It is shown that the total number of strokes in lightning process is mainly decided by environmental temperature at altitude with the residual instability of 5℃(T_r).The instability should also affect the total number of strokc in lightning process.A forecasting equation of stroke in light- ning process has been deduced and two interesting preliminary conclusions have been obtained.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.
基金Supported by the Science and Technology Plan Project in Meizhou Region(2016B204)
文摘Based on the cloud-to-ground（ CG） lightning flashes data and other related data from 1999 to 2016,the lightning risk zoning of Meizhou was conducted by using the analytic hierarchy process（ AHP） model. The model considered the natural conditions,social economic conditions and other factors,and the main assessment factors were selected,containing ＂ flash density,lightning current intensity,annual thunderstorm days,lightning disaster frequency,construction area per capita and GDP per capita＂,in order to establish the evaluation model,and divide the level of risk. The results showed that the lightning risk in Meizhou area roughly had the trend of ＂ center higher than all-around,the south higher than the north,the west higher than the east＂. High-risk area was in the most region of Meijiang District and central region of Meixian District,and Wuhua County was next high-risk area. Xingning City and Fengshun County were medium risk areas,most of the other were low risk area. The result of regionalization was consistent with the actual situation,and the evaluation method was scientific and effective. Through the analysis of the lightning risk zoning,this paper could provide a scientific basis for the lightning protection and disaster reduction in the region in the future.
文摘By using monitoring data of lightning locating system in Hebei during 1999- 2010 and lightning disaster data in Hebei during 2002- 2010,temporal-spatial distribution characteristics of ground flash and lightning disaster in Hebei Province were analyzed. Annual,monthly and daily changes of ground flash,lightning current intensity and ground flash density in Hebei were analyzed,and we compared ground flash with lightning disaster distribution.
文摘The problems in calculating parameters of equivalent collection area,earth resistivity and lightning protection category as well as their effects on lightning disaster risk assessment were analyzed,and practical examples proved the effects of those differences on lightning protection identification,intercept efficiency calculation in evaluating lightning disaster risk. In the meantime,several new concepts,such as the height of buildings for lightning protection were defined,and a fixed radius value was set to the ground flash density for calculation,establishing the ground flash density formula to solve the problems in parameter calculation,which would be beneficial to promote the standardization of lightning disaster risk assessment.
文摘Simultaneous observations for the total column densities of NO2,O3 and H2O were carried on using the portable Spectrometer (438-450 nm and 400-450 nm) and the visible Spectrometer (544.4-628 nm) during premonsoon thunderstorms and embedded hail storm activity at Pune (18°32'N & 73°51'E),India.These observations confirm the fact that there is an increase in O3 and NO2 column densities during thunderstorms.The increase in O3 was observed following onset of thunderstorm,while the increase in NO2 was observed only after the thunder flashes occur.This implies that the production mechanisms for O3 and NO2 in thunderstorm are different.The observed column density of NO,value (1 to 3×1017molecules cm-2) during thunderstorm activity is 10 to 30 times higher than the value (1×10th molecules cm-2) of a normal day total column density.The spectrometric observations and observations of thunder flashes by electric field meter showed that 6.4×1025molecules/flash of NO2 are produced.The increased to-oil column density of ozone during thunderstorm period is 1.2 times higher than normal (clear) day ozone concentration.The multiple scattering in the clouds is estimated from H2O and O2 absorption bands in the visible spectral region Considering this effect the calculated amount of ozone added in the global atmosphere due to thunderstorm activity is 0.26 to 0 52 DU,and the annual production of ozone due to thunderstorm activity is of the order of 4.02×10 molecules/year The annual NO2 production may be of the order of 2.02×1035molecules/year.
基金primarily supported by the National Natural Science Foundation of China(Grant Nos.42025501,41905019,and 61827901)the National Key Research and Development Program of China(Grant 2018YFC1506404 and Grant 2017YFC1501703)。
文摘During the pre-summer rainy season,heavy rainfall occurs frequently in South China.Based on polarimetric radar observations,the microphysical characteristics and processes of convective features associated with extreme rainfall rates(ERCFs)are examined.In the regions with high ERCF occurrence frequency,sub-regional differences are found in the lightning flash rate(LFR)distributions.In the region with higher LFRs,the ERCFs have larger volumes of high reflectivity factor above the freezing level,corresponding to more active riming processes.In addition,these ERCFs are more organized and display larger spatial coverage,which may be related to the stronger low-level wind shear and higher terrain in the region.In the region with lower LFRs,the ERCFs have lower echo tops and lower-echo centroids.However,no clear differences of the most unstable convective available potential energy(MUCAPE)exist in the ERCFs in the regions with different LFR characteristics.Regardless of the LFRs,raindrop collisional coalescence is the main process for the growth of raindrops in the ERCFs.In the ERCFs within the region with lower LFRs,the main mechanism for the rapid increase of liquid water content with decreasing altitude below 4 km is through the warm-rain processes converting cloud drops to raindrops.However,in those with higher LFRs,the liquid water content generally decreases with decreasing altitude.
文摘Based on the transmission line equations, this paper has developed computing formulas of current and voltage induced on the cable over the ground plane by Flash of Lightning Between Clouds (FBC), and estimated current and voltage on the cable of metal shielded sheath and analyzed the results.
文摘In this paper the statistical analysis is carried out on the correlation between lightning strokes and atmospheric stratification factors.It is shown that the total number of strokes in lightning process is mainly decided by environmental temperature at altitude with the residual instability of 5℃(T_r).The instability should also affect the total number of strokc in lightning process.A forecasting equation of stroke in light- ning process has been deduced and two interesting preliminary conclusions have been obtained.
