scholarly journals Characteristics of cloud-to-ground lightning activity over Seoul, South Korea in relation to an urban effect

2007 ◽  
Vol 25 (10) ◽  
pp. 2113-2118 ◽  
Author(s):  
S. K. Kar ◽  
Y.-A. Liou ◽  
K.-J. Ha
Keyword(s):  
South Korea ◽  
Correlation Coefficients ◽  
Lightning Activity ◽  
Lightning Flash ◽  
Urban Effect ◽  
Percentage Decrease ◽  
Lightning Detection ◽  
Cloud To Ground Lightning ◽  
The City ◽  
Cg Lightning

Abstract. Cloud-to-ground (CG) lightning flash data collected by the lightning detection network installed at the Korean Meteorological Administration (KMA) have been used to study the urban effect on lightning activity over and around Seoul, the largest metropolitan city of South Korea, for the period of 1989–1999. Negative and positive flash density and the percentage of positive flashes have been calculated. Calculation reveals that an enhancement of approximately 60% and 42% are observed, respectively, for negative and positive flash density over and downwind of the city. The percentage decrease of positive flashes occurs over and downwind of Seoul and the amount of decrease is nearly 20% compared to upwind values. The results are in good agreement with those obtained by Steiger et al. (2002) and Westcott (1995). CG lightning activities have also been considered in relation to annual averages of PM10 (particulate matter with an aerodynamic diameter smaller than 10 μm) and sulphur dioxide (SO2) concentrations. Interesting results are found, indicating that the higher concentration of SO2 contributes to the enhancement of CG lightning flashes. On the other hand, the contribution from PM10 concentration has not appeared in this study to be as significant as SO2 in the enhancement of CG lightning flashes. Correlation coefficients of 0.33 and 0.64 are found between the change in CG lightning flashes and the PM10 and SO2, respectively, for upwind to downwind areas, suggesting a significant influence of the increased concentration of SO2 on the enhancement of CG flashes.

scholarly journals Enhancement of Cloud-to-Ground Lightning Activity Caused by the Urban Effect: A Case Study in the Beijing Metropolitan Area

2021 ◽  
Vol 13 (7) ◽  
pp. 1228
Author(s):  
Yongping Wang ◽  
Gaopeng Lu ◽  
Tao Shi ◽  
Ming Ma ◽  
Baoyou Zhu ◽  
...  
Keyword(s):  
Metropolitan Area ◽  
Industrial Area ◽  
Lightning Activity ◽  
Beijing Area ◽  
Factors Affecting ◽  
Pollutant Concentrations ◽  
Lightning Detection ◽  
Cloud To Ground Lightning ◽  
Beijing Metropolitan Area ◽  
Cg Lightning

To investigate the possible impact of urban development on lightning activity, an eight-year (2010–2017) cloud-to-ground (CG) lightning dataset provided by the National-Wide Lightning Detection Network in China was analyzed to characterize the CG lightning activity in the metropolitan area of Beijing. There is a high CG flash density area over the downtown of Beijing, but different from previous studies, the downwind area of Beijing is not significantly enhanced. Compared with the upwind area, the CG flash density in the downtown area was enhanced by about 50%. Negative CG flashes mainly occurred in the downtown and industrial area, while positive CG flashes were distributed evenly. The percentage of positive CG flashes with Ipeak ≥ 75 kA is more than six times that of the corresponding negative CG flashes in the Beijing area. The enhancement of lightning activity varies with season and time. About 98% of CG flashes occurred from May to September, and the peak of CG diurnal variation is from 1900 to 2100 local time. Based on the analysis of thunderstorm types in Beijing, it is considered that the abnormal lightning activity is mainly responsible for an enhancement of the discharge number in frontal systems rather than the increase of the number of local thunderstorms. In addition, there is a non-linear relationship between pollutant concentrations and CG flash number, which indicates that there are other critical factors affecting the production of lightning.

scholarly journals A Cloud-to-Ground Lightning Climatology for Poland

2015 ◽  
Vol 143 (11) ◽  
pp. 4285-4304 ◽  
Author(s):  
Mateusz Taszarek ◽  
Bartosz Czernecki ◽  
Aneta Kozioł
Keyword(s):  
Annual Number ◽  
Lightning Flash ◽  
Grid Cells ◽  
Lake District ◽  
Negative Current ◽  
Lightning Detection ◽  
Cloud To Ground Lightning ◽  
The Mean ◽  
The Baltic ◽  
Cg Lightning

Abstract This research focuses on the climatology of cloud-to-ground (CG) lightning flashes based on PERUN lightning detection network data from 2002 to 2013. To present various CG lightning flash characteristics, 10 km × 10 km grid cells are used, while for estimating thunderstorm days, circles with radii of 17.5 km in the 1 km × 1 km grid cells are used. A total of 4 328 892 CG lightning flashes are used to analyze counts, density, polarity, peak current, and thunderstorm days. An average of 151 days with thunderstorm (appearing anywhere in Poland) occurs each year. The annual number of days with thunderstorms increases southeasterly from the coast of the Baltic Sea (15–20 days) to the Carpathian Mountains (30–35 days). The mean CG lightning flash density varies from 0.2 to 3.1 flashes km−2 yr−1 with the highest values in the southwest–northeast belt from Kraków-Częstochowa Upland to the Masurian Lake District. The maximum daily CG lightning flash density in this region amounted to 9.1 km−2 day−1 (3 July 2012). The monthly variation shows a well-defined thunderstorm season extending from May to August with July as the peak month. The vast majority of CG lightning flashes were detected during the daytime (85%) with a peak at 1400 UTC and a minimum at 0700 UTC. Almost 97% of all CG lightning flashes in the present study had a negative current, reaching the highest average monthly values in February (55 kA) and the lowest in July (24 kA). The percentage of positive CG lightning flashes was the lowest during the summer (2%–3%) and the highest during the winter (10%–20%).

Summertime Cloud-to-Ground Lightning Activity around Major Midwestern Urban Areas

1995 ◽  
Vol 34 (7) ◽  
pp. 1633-1642 ◽  
Author(s):  
Nancy E. Westcott
Keyword(s):  
Urban Areas ◽  
Cloud Condensation Nuclei ◽  
Thunderstorm Activity ◽  
Lightning Activity ◽  
Lightning Flash ◽  
Storm Activity ◽  
Topographic Features ◽  
Activity Frequency ◽  
Lightning Detection ◽  
Cloud To Ground Lightning

Abstract Cloud-to-ground lightning flash data collected by the National Lightning Detection Network were analysed in and around 16 central U.S. cities for the period 1989–92. Lightning data are well suited to study storm activity in and around large urban areas since their continuity and coverage in space and time is superior to historical, spatially limited records of thunderstorm activity. Frequency of cloud-to-ground lightning flashes (of negative and positive polarity) in the area immediately upwind, within, and immediately downwind of the cities were compared. An enhancement of lightning frequency on the order of 40%–85% was found over and downwind of many of these cities. A number of possible urban-related causal factors were examined including effects of increased urban concentrations of cloud condensation nuclei, urban population and size, and the presence of distinct topographic features in and around the cities. Various factors, physical and anthropogenic, appeared to interact in diverse ways to account for changes in lightning flash frequency. The enhancement of lightning activity was largest during the afternoon hours when the urban–rural temperature differences are usually smallest, but when the atmosphere is generally the most unstable and when there is often a maximum in convective activity. The spatial distribution of the first 50 lightning flashes from each storm suggested that the urban area did not initiate new lightning storms. Thus, the overall results suggested that existing thunderstorms were the most strongly affected.

scholarly journals Distinct aerosol effects on cloud-to-ground lightning in the plateau and basin regions of Sichuan, Southwest China

2020 ◽  
Vol 20 (21) ◽  
pp. 13379-13397
Author(s):  
Pengguo Zhao ◽  
Zhanqing Li ◽  
Hui Xiao ◽  
Fang Wu ◽  
Youtong Zheng ◽  
...  
Keyword(s):  
Cloud Droplet ◽  
Lightning Activity ◽  
Freezing Process ◽  
Plateau Region ◽  
Freezing Level ◽  
Aerosol Loading ◽  
Cloud To Ground Lightning ◽  
Basin Region ◽  
Total Column ◽  
Cg Lightning

Abstract. The joint effects of aerosol, thermodynamic, and cloud-related factors on cloud-to-ground lightning in Sichuan were investigated by a comprehensive analysis of ground-based measurements made from 2005 to 2017 in combination with reanalysis data. Data include aerosol optical depth, cloud-to-ground (CG) lightning density, convective available potential energy (CAPE), mid-level relative humidity, lower- to mid-tropospheric vertical wind shear, cloud-base height, total column liquid water (TCLW), and total column ice water (TCIW). Results show that CG lightning density and aerosols are positively correlated in the plateau region and negatively correlated in the basin region. Sulfate aerosols are found to be more strongly associated with lightning than total aerosols, so this study focuses on the role of sulfate aerosols in lightning activity. In the plateau region, the lower aerosol concentration stimulates lightning activity through microphysical effects. Increasing the aerosol loading decreases the cloud droplet size, reducing the cloud droplet collision–coalescence efficiency and inhibiting the warm-rain process. More small cloud droplets are transported above the freezing level to participate in the freezing process, forming more ice particles and releasing more latent heat during the freezing process. Thus, an increase in the aerosol loading increases CAPE, TCLW, and TCIW, stimulating CG lightning in the plateau region. In the basin region, by contrast, the higher concentration of aerosols inhibits lightning activity through the radiative effect. An increase in the aerosol loading reduces the amount of solar radiation reaching the ground, thereby lowering the CAPE. The intensity of convection decreases, resulting in less supercooled water being transported to the freezing level and fewer ice particles forming, thereby increasing the total liquid water content. Thus, an increase in the aerosol loading suppresses the intensity of convective activity and CG lightning in the basin region.

scholarly journals The European lightning location system EUCLID – Part 2: Observations

2016 ◽  
Vol 16 (2) ◽  
pp. 607-616 ◽  
Author(s):  
Dieter Roel Poelman ◽  
Wolfgang Schulz ◽  
Gerhard Diendorfer ◽  
Marina Bernardi
Keyword(s):  
Diurnal Cycle ◽  
Lightning Activity ◽  
European Continent ◽  
Peak Current ◽  
Location System ◽  
European Cooperation ◽  
Lightning Detection ◽  
Lightning Location System ◽  
Cg Lightning

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

Detecting Multiple Ground Contacts in Cloud-to-Ground Lightning Flashes

2009 ◽  
Vol 26 (11) ◽  
pp. 2392-2402 ◽  
Author(s):  
Christina A. Stall ◽  
Kenneth L. Cummins ◽  
E. Philip Krider ◽  
John A. Cramer
Keyword(s):  
Standard Deviation ◽  
Rise Time ◽  
Random Errors ◽  
Peak Current ◽  
Video Recordings ◽  
Lightning Detection ◽  
Cloud To Ground Lightning ◽  
The U.S ◽  
Good Agreement ◽  
Cg Lightning

Abstract Video recordings of cloud-to-ground (CG) lightning flashes have been analyzed in conjunction with correlated stroke reports from the U.S. National Lightning Detection Network (NLDN) to determine whether the NLDN is capable of identifying the different ground contacts in CG flashes. For 39 negative CG flashes that were recorded on video near Tucson, Arizona, the NLDN-based horizontal distances between the first stroke and the 62 subsequent strokes remaining in a preexisting channel had a mean and standard deviation of 0.9 ± 0.8 km and a median of 0.7 km. The horizontal distances between the first stroke and the 59 new ground contacts (NGCs) had a mean and standard deviation of 2.3 ± 1.7 km and a median of 2.1 km. These results are in good agreement with prior measurements of the random errors in NLDN positions in southern Arizona as well as video- and thunder-based measurements of the distances between all ground contacts in Florida. In cases where the distances between ground contacts are small and obscured by random errors in the NLDN locations, measurements of the stroke rise time, estimated peak current, and stroke order can be utilized to enhance the ability of the NLDN to identify strokes that produce new ground terminations.

scholarly journals Analysis of cloud-to-ground lightning and its relation with surface pollutants over Taipei, Taiwan

2014 ◽  
Vol 32 (9) ◽  
pp. 1085-1092 ◽  
Author(s):  
S. K. Kar ◽  
Y. A. Liou
Keyword(s):  
Lower Troposphere ◽  
Lightning Activity ◽  
Background Concentration ◽  
Moderate Resolution ◽  
Cloud To Ground Lightning ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Two Parameters ◽  
Enhanced Surface ◽  
Cg Lightning

Abstract. Premonsoon (March–April) cloud-to-ground (CG) lightning activity over Taipei, Taiwan, is analyzed in relation to surface pollutants like particulate matter (PM10), sulfur dioxide (SO2), nitrogen oxides (NOx) and ozone (O3) concentration for a period of 6 years (2005–2010). Other surface parameters like aerosol optical depth and cloud top temperature are also investigated taking data from Moderate Resolution Imaging Spectroradiometer satellite products. Results reveal that SO2 is more strongly associated with CG lightning activity compared to PM10 concentration. Other surface pollutants like NOx and O3 also show strong linear association with CG lightning flashes. Additional investigations have also been performed to extreme lightning events, particularly to a few long-lasting lightning episodes considering the concentrations of NOx and O3 found on days with no lightning activity as representative of the background concentration levels of the said two parameters. Results indicate that the NOx concentration on days with lightning activity is more than 2-fold compared to the non-lightning days while the O3 concentration is increased by 1.5-fold. Such increase in NOx and O3 concentration on days with lightning strongly supports the transport phenomena of NOx and O3 from the upper or middle troposphere to the lower troposphere by downdraft of the thunderstorm during its dissipation stage. Overall, studies suggest that enhanced surface pollution in a near-storm environment is strongly related to the increased lightning activity, which in turn increases the surface NOx level and surface O3 concentration over the area under study.

scholarly journals Diurnal Variations of NLDN-Reported Cloud-to-Ground Lightning in the United States

2014 ◽  
Vol 142 (3) ◽  
pp. 1037-1052 ◽  
Author(s):  
Ronald L. Holle
Keyword(s):  
United States ◽  
The United States ◽  
Maximum Activity ◽  
Lightning Flash ◽  
Diurnal Changes ◽  
Lightning Detection ◽  
Cloud To Ground Lightning ◽  
Local Mean ◽  
Composite Maps ◽  
Mean Time

Abstract National maps of cloud-to-ground lightning flash density (in flashes per square kilometer per year) for one or more years have been produced since the National Lightning Detection Network (NLDN) was first deployed across the contiguous United States in 1989. However, no single publication includes maps of cloud-to-ground flash density across the domain and adjacent areas during the entire diurnal cycle. Cloud-to-ground lightning has strong and variable diurnal changes across the United States that should be taken into account for outdoor lightning-vulnerable activities, particularly those involving human safety. For this study, NLDN cloud-to-ground flash data were compiled in 20 km by 20 km grid squares from 2005 to 2012 for the lower 48 states. A unique feature of this study is that maps were prepared to coincide with local time, not time zones. NLDN flashes were assigned to 2-h time periods in 5° longitude bands. Composite maps of the 2-h periods with the most lightning in each grid square were also prepared. The afternoon from 1200 to 1800 local mean time provides two-thirds of the day’s lightning. However, lightning activity starts before noon over western mountains and onshore along the Atlantic and Gulf of Mexico coasts. These areas are where recurring lightning-vulnerable recreation and workplace activities should expect the threat at these times, rather than view them as an anomaly. An additional result of the study is the midday beginning of lightning over the higher terrain of the western states, then the maximum activity moves steadily eastward. These storms pose a threat to late-afternoon and evening recreation. In some Midwest and plains locations, lightning is most frequent after midnight.

scholarly journals The Daily Cloud-to-Ground Lightning Flash Density in the Contiguous United States and Finland

2011 ◽  
Vol 139 (5) ◽  
pp. 1323-1337 ◽  
Author(s):  
Antti Mäkelä ◽  
Pekka Rossi ◽  
David M. Schultz
Keyword(s):  
United States ◽  
Detection Efficiency ◽  
Quantitative Measure ◽  
The United States ◽  
Lightning Flash ◽  
Upper Midwest ◽  
Lightning Detection ◽  
Operational Forecasting ◽  
Central United States ◽  
Cloud To Ground Lightning

A method is developed to quantify thunderstorm intensity according to cloud-to-ground lightning flashes (hereafter ground flashes) determined by a lightning-location sensor network. The method is based on the ground flash density ND per thunderstorm day (ground flashes per square kilometer per thunderstorm day) calculated on 20 km × 20 km fixed squares. Because the square size roughly corresponds to the area covered by a typical thunderstorm, the flash density for one square defines a unit thunderstorm for the purposes of this study. This method is tested with ground flash data obtained from two nationwide lightning-location systems: the National Lightning Detection Network (NLDN) in the contiguous United States and the portion of the Nordic Lightning Information System (NORDLIS) in Finland. The distribution of daily ground flash density ND is computed for all of Finland and four 800 000 km2 regions in the United States (identified as western, central, eastern, and Florida). Although Finland and all four U.S. regions have median values of ND of 0.01–0.03 flashes per square kilometer per thunderstorm day—indicating that most thunderstorms produce relatively few ground flashes regardless of geographical region—the most intense 1% of the storms (as measured by the 99th percentiles of the ND distributions within each region) show much larger differences among regions. For example, the most intense 1% of the ND distributions is 1.3 flashes per square kilometer per thunderstorm day in the central U.S. region, but only 0.2 flashes per square kilometer per thunderstorm day in Finland. The spatial distribution of the most intense 1% of the ND distributions illustrates that the most intense thunderstorm days occur in the central United States and upper Midwest, which differs from the maxima of the average annual flash density NA and the number of thunderstorm days TD, both of which occur in Florida and along the coast of the Gulf of Mexico. This method for using ND to quantify thunderstorm intensity is applicable to any region as long as the detection efficiency of the lightning-location network is high enough or known. This method can also be employed in operational forecasting to provide a quantitative measure of the lightning intensity of thunderstorms relative to climatology.

Probability of Tornado Occurrence across Canada

2013 ◽  
Vol 26 (23) ◽  
pp. 9415-9428 ◽  
Author(s):  
Vincent Y. S. Cheng ◽  
George B. Arhonditsis ◽  
David M. L. Sills ◽  
Heather Auld ◽  
Mark W. Shephard ◽  
...  
Keyword(s):  
Population Density ◽  
Grid Cell ◽  
Sampling Bias ◽  
Lightning Flash ◽  
Storm Activity ◽  
Damage Area ◽  
Population Sampling ◽  
Lightning Detection ◽  
Explicit Consideration ◽  
Cg Lightning

The number of tornado observations in Canada is believed to be significantly lower than the actual occurrences. To account for this bias, the authors propose a Bayesian modeling approach founded upon the explicit consideration of the population sampling bias in tornado observations and the predictive relationship between cloud-to-ground (CG) lightning flash climatology and tornado occurrence. The latter variable was used as an indicator for quantifying convective storm activity, which is generally a precursor to tornado occurrence. The CG lightning data were generated from an 11-yr lightning climatology survey (1999–2009) from the Canadian Lightning Detection Network. The results suggest that the predictions of tornado occurrence in populated areas are fairly reliable with no profound underestimation bias. In sparsely populated areas, the analysis shows that the probability of tornado occurrence is significantly higher than what is represented in the 30-yr data record. Areas with low population density but high lightning flash density demonstrate the greatest discrepancy between predicted and observed tornado occurrence. A sensitivity analysis with various grid sizes was also conducted. It was found that the predictive statements supported by the model are fairly robust to the grid configuration, but the population density per grid cell is more representative to the actual population density at smaller resolution and therefore more accurately depicts the probability of tornado occurrence. Finally, a tornado probability map is calculated for Canada based on the frequency of tornado occurrence derived from the model and the estimated damage area of individual tornado events.

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