The CG lightning activity of a storm causing a flash-flood

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.

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The European lightning location system EUCLID – Part 2: Observations

Natural Hazards and Earth System Science ◽

10.5194/nhess-16-607-2016 ◽

2016 ◽

Vol 16 (2) ◽

pp. 607-616 ◽

Cited By ~ 42

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.

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Cloud-to-Ground Lightning Distribution and Its Relationship with Orography and Anthropogenic Emissions in the Po Valley

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-14-0037.1 ◽

2014 ◽

Vol 53 (12) ◽

pp. 2651-2670 ◽

Cited By ~ 18

Author(s):

Laura Feudale ◽

Agostino Manzato

Keyword(s):

The United States ◽

Lightning Activity ◽

Anthropogenic Emissions ◽

Target Area ◽

Mountain Areas ◽

Weekly Cycle ◽

Po Valley ◽

Mountainous Regions ◽

Area Of Interest ◽

Cg Lightning

AbstractThe main object of this work is to study the lightning climatology in the Po Valley in Italy and how it varies in time (interannual, annual, weekly, and daily time scales) and space (sea coast, plains, and mountain areas) and how that is related to topographic characteristics and anthropogenic emissions. Cloud-to-ground (CG) lightning in the target area is analyzed for 18 yr of data (about 7 million records). It is found that the Julian Prealps of the Friuli Venezia Giulia region are one of the areas of maximum CG lightning activity across all of Europe. During spring lightning activity is more confined toward the mountainous regions, whereas during summer and even more during autumn the lightning activity involves also the coastal region and the Adriatic Sea. This is due to different triggering mechanisms acting in different topographic zones and during different periods of the year and times of the day. In analogy to previous studies of lightning done in the United States, a weekly cycle is also identified in the area of interest, showing that on Friday the probability of thunderstorms reaches its maximum. After conducting a parallel analysis with monitoring stations of atmospheric particulates (diameter ≤ 10 μm: PM10) and sounding-derived potential instability, the results presented herein seem to support the hypothesis that the weekly cycle in the thunderstorm activity may be due to anthropogenic emissions.

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

Annales Geophysicae ◽

10.5194/angeo-32-1085-2014 ◽

2014 ◽

Vol 32 (9) ◽

pp. 1085-1092 ◽

Cited By ~ 4

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.

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SAFIR-3000 Lightning Statistics over the Beijing Metropolitan Region during 2005–07

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-16-0030.1 ◽

2016 ◽

Vol 55 (12) ◽

pp. 2613-2633 ◽

Cited By ~ 9

Author(s):

Fan Wu ◽

Xiaopeng Cui ◽

Da-Lin Zhang ◽

Dongxia Liu ◽

Dong Zheng

Keyword(s):

Spatial Pattern ◽

Early Morning ◽

Spatial Variations ◽

Lightning Activity ◽

Metropolitan Region ◽

Topographic Effects ◽

Spatiotemporal Variations ◽

Opposite Pattern ◽

Late Night ◽

Cg Lightning

AbstractIn this study, the spatiotemporal characteristics of cloud-to-ground (CG) and intracloud (IC) lightning flashes observed by Surveillance et Alerte Foudre par Interférometrie Radioélectrique (SAFIR)-3000 over the Beijing metropolitan region (BMR) during 2005–07 were investigated. The results showed the presence of 299 lightning days with 241 688 flashes, most of which were IC lightning flashes. Only 19% of the total flashes were CG lightning flashes; 14% of these CG flashes were positive. Most lightning activity occurred during the summer months (June–August), with a major diurnal peak around 1900 Beijing standard time (BST) and a secondary peak around 2300 BST. Spatial variations in flash density and lightning days both exhibited an obvious southeastwardly increasing pattern, with higher flash densities or more lightning days occurring in the southeastern plains and lower values distributed on the northwestern mountains. The Z ratio (IC/CG lightning flashes) exhibited a similar spatial pattern, but the percentage of positive CG lightning flashes showed an almost opposite pattern. The results also showed significant topographic effects on the spatiotemporal variations in lightning activity. That is, flash counts on the northeastern and southwestern mountains peaked in the afternoon, whereas those on the southeastern plains peaked in the late night to early morning, which could be attributed to the propagation of thunderstorms from the mountains to the plains. The results showed that the SAFIR-3000 lightning data are more useful than CG lightning data alone for forecasting the development and propagation of thunderstorms over the BMR.

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Lightning activity, rainfall and flash flooding – occasional or interrelated events? A case study in the island of Crete

Natural Hazards and Earth System Science ◽

10.5194/nhess-12-881-2012 ◽

2012 ◽

Vol 12 (4) ◽

pp. 881-891 ◽

Cited By ~ 19

Author(s):

A. G. Koutroulis ◽

M. G. Grillakis ◽

I. K. Tsanis ◽

V. Kotroni ◽

K. Lagouvardos

Keyword(s):

Flash Flood ◽

Detection System ◽

Time Lag ◽

Spatiotemporal Analysis ◽

Lightning Activity ◽

Precipitation Event ◽

Time Lags ◽

Flood Events ◽

Synoptic Conditions ◽

High Precipitation

Abstract. The majority of cyclones passing over Crete in late autumn to early winter originate from southwest, west and northwest and are of varying size and intensity. A number of these cyclones cause flash floods. The present study reports the possible relationships between lighting activity and high precipitation related to flash flood events. In this study an attempt was made to correlate the lightning number and location, recorded by the ZEUS lightning detection system, with the rainfall characteristics for sixteen rain events (4 flood and 12 non-flood events) on the island of Crete, during the period 2008–2009. Spatiotemporal analysis of rain and rain rate with flash count was performed with respect to distance (radius) of flashes from raingauge location at various temporal scales, in order to examine the correlation of accumulated rainfall and lightning activity. The maximum attained statistical significant correlation was obtained within a circular area of an average radius of 15 km around the raingauge, and an average time lag of flash count prior precipitation accumulation of 15 min. The maximum correlation between the lightning and rainfall data is obtained for shorter time lags for the flood events (15 min) than the non-flood events (25 min), that could reflect the faster propagation of flood triggering storms due to high convective activity. Results show increased lightning activity occurring during flood triggering storms, by an average of four times higher. Furthermore, there is evidence that the number of flashes that occur during a precipitation event is related to precipitation depth when the latter is adequate to produce a flood event. Differences between flood and non-flood producing storms need to be further assessed by analyzing more independent parameters, including the synoptic conditions and dominant flash flood hydrological generating processes.

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

Remote Sensing ◽

10.3390/rs13071228 ◽

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.

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

10.5194/acp-2020-429 ◽

2020 ◽

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 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 reduces 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 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 aerosol loading reduces the amount of solar radiation reaching the ground, thereby lowering CAPE. The intensity of convection decreases, resulting in less supercooled water transported to the freezing level and fewer ice particles forming, thus increasing the total liquid water content. Therefore, an increase in aerosol loading suppresses the intensity of convective activity and CG lightning in the basin region.

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Lightning and rain dynamic indices as predictors for flash floods events in the Mediterranean

Advances in Geosciences ◽

10.5194/adgeo-23-57-2010 ◽

2010 ◽

Vol 23 ◽

pp. 57-64 ◽

Cited By ~ 15

Author(s):

N. Harats ◽

B. Ziv ◽

Y. Yair ◽

V. Kotroni ◽

U. Dayan

Keyword(s):

Flash Flood ◽

Heavy Precipitation ◽

Flash Floods ◽

Lightning Activity ◽

Specific Humidity ◽

Flood Events ◽

Funded Project ◽

The Mediterranean ◽

Good Concordance ◽

Short Term Forecasting

Abstract. The FLASH EU funded project aims to observe, analyze and model lightning activity in thunderstorms for use in short term forecasting of flash floods in the Mediterranean region. Two new indices, aimed to assess the potential for heavy precipitation and flash-floods, are proposed and evaluated. The first is a lightning index – the MKI, which is a modified version of the KI-index. The applied index gives more weight to the lower- and mid-level relative humidity. The second is a new rain index, the RDI, which is the integrated product of specific humidity and vertical velocity. With the aim to contribute to the aforementioned objectives, 3 flash flood events, two in Israel and one in Greece are analyzed in the present study, using the 2 proposed indices. The NCEP/NCAR reanalysis database, of 2.5°×2.5° resolution, failed to resolve the meso-scale features of the observed flash flood events. Therefore, the ECWMF database, of 0.5°×0.5° resolution, was used for calculating and displaying the two indices. Comparison between the observed rain and lightning and the respective indices for the two pieces of data was performed for the flash flood events. The results show good concordance of both indices with timing and spatial distribution in 2 of them, while in one of them is displaced by more than 50 km. The good agreement in locating the maximum between the MKI and RDI suggests that the proposed indices are good predictors for both intense lightning activity and torrential rain and consequently, for potential flash floods.

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The European lightning location system EUCLID – Part 2: Observations

Natural Hazards and Earth System Sciences Discussions ◽

10.5194/nhessd-3-5357-2015 ◽

2015 ◽

Vol 3 (9) ◽

pp. 5357-5381 ◽

Cited By ~ 4

Author(s):

D. R. Poelman ◽

W. Schulz ◽

G. Diendorfer ◽

M. Bernardi

Keyword(s):

Triple Point ◽

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 triple point 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 numbers over sea than over land.

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