Variation Of Lightning Activity Research Articles

The influence of lightning activity on NOx and O3 in the Pearl River Delta region

Extremely high-temperature lightning generates NOx by electrolyzing nitrogen and oxygen molecules, regulating ozone concentration. The Pearl River Delta (PRD) is located in the world's high-value area of lightning density, and lightning-generated NOx (LNOx) cannot be ignored. Using the flash data from Guangdong-Hong Kong-Macao Lightning Location System and multi-site atmospheric composition data, we estimate the NOx variations in lightning activity and its impact on O3 across the PRD region. The cloud-to-groud (CG) frequency from 2013 to 2021 shows a decreasing trend driven by urban regions. We observe that the lightning density is steadily decreasing from the south-central part of Guangzhou City to the surrounding area.A comparison of the different sites with lightning days and non-lightning days shows that a significant amount (13. 84–20. 47 %) of ground-level NOx concentration at urban stations can be attributed to lightning NOx emissions. A lower lightning frequency and low background concentration observed at suburban sites indicated a limited contribution of LNOx. The average decrease in O3 concentration at urban stations (15.92–25.06 %) was significantly higher than that at suburban stations (5.34–8.95 %) due to the influence of titration and lower actinic radiation. There was a greater fluctuation in NOx and O3 concentrations during the cases, and the surface NOx concentration displayed the most significant responsiveness to LNOx under direct lightning striking in the tall tower. This phenomenon has not been reported, however, it is consistent with the laboratory-based observations suggesting the amount of LNO increases with peak current. LNOx significantly impacts air quality in the PRD during the high convective season. Further in situ and vertical distribution observations are necessary to explore the ground-level impact of LNOx.

Lightning activity in Yakutia and its impact on the networks of PJSC Yakutskenergo

It is shown that daily, seasonal and interannual variations in the number of lightning outages in the Central and Western energy district regions of Yakutia correspond to variations in lightning activity in the area where these networks are located. The annual number of lightning outages was from 35 to 65. The daily variation has the form of a one-period wave with a maximum at 19:00 local time and a minimum at 7:00 LT. In the total diurnal variation over 7 years around 7 LT, about two outages were observed, while at 19 LT the total number reached 25. The similarity of daily, annual, and interannual variations in lightning activity and the number of thunderstorm outages indicates the absence of special features in the discharges that lead to thunderstorm outages of high-voltage networks.

Assessment of a Ground-Based Lightning Detection and Near-Real-Time Warning System in the Rural Community of Swayimane, KwaZulu-Natal, South Africa

AbstractClimate change projections of increases in lightning activity are an added concern for lightning-prone countries such as South Africa. South Africa’s high levels of poverty, lack of education, and awareness, as well as a poorly developed infrastructure, increase the vulnerability of rural communities to the threat of lightning. Despite the existence of national lightning networks, lightning alerts and warnings are not disseminated well to such rural communities. We therefore developed a community-based early warning system (EWS) to detect and disseminate lightning threats and alerts in a timely and comprehensible manner within Swayimane, KwaZulu-Natal, South Africa. The system is composed of an electrical field meter and a lightning flash sensor with warnings disseminated via audible and visible alarms on site and with a remote server issuing short message services (SMSs) and email alerts. Twelve months of data (February 2018–February 2019) were utilized to evaluate the performance of the EWS’s detection and warning capabilities. Diurnal variations in lightning activity indicated the influence of solar radiation, causing convective conditions with peaks in lightning activity occurring during the late afternoon and early evening (between 1400 and 2100) coinciding with students being released from school and when most workers return home. In addition to detecting the threat of lightning, the EWS was beneficial in identifying periods that exhibited above-normal lightning activity, with two specific lightning events examined in detail. Poor network signals in rural communities presented an initial challenge, delaying data transmission to the central server until rectified using multiple network providers. Overall, the EWS was found to disseminate reliable warnings in a timely manner.

Variability of lightning activity over India on ENSO time scales

ENSO, the reliable indicator of inter-annual climate variation of the ocean-atmosphere system in the tropical Pacific region, can affect the overall lightning activity which is another atmospheric phenomenon. In the present study, the impact of the ENSO on the total lightning activity over India has been studied for the period 2004–2014. During the El-Nino period (July 2004–April 2005 and July 2009–April 2010), total number of lightning flashes increased by 10% and 18% respectively and during La-Nina period (July 2010–April 2011 and August 2011 to March 2012), the total number of lightning flashes decreased approximately by 19% and 28% respectively as compared to the mean of corresponding period (2004–14) of the Non-ENSO. Seasonal variation of flash density is also examined for the El-Nino and La-Nina period. The result shows that in the El-Nino period of the pre-monsoon and monsoon seasons, there is an increment in the flash density approximately by 48% and 9% respectively than the Non-ENSO and the spatial variation also having high flash density along the foot of Himalayas region. In the post-monsoon season, there is a marginal change in the flash density between El-Nino and the Non-ENSO. In the winter season, there is an increment in flash density in the El-Nino period approximately by 45% than the Non-ENSO. In the La-Nina period of the pre-monsoon and monsoon seasons, there is the decrement in the flash density approximately by the 44% and 24% respectively than the Non-ENSO. In the Post-monsoon season and winter season of La-Nina, the flash density is increased by about 24% and 33% over India. These findings can be applied to do proper planning of lightning induced hazard mitigation as lightning is of one of the major natural disasters of India.

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

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.

Seasonal forecasting of lightning and thunderstorm activity in tropical and temperate regions of the world.

Thunderstorms are convective systems characterised by the occurrence of lightning. Lightning and thunderstorm activity has been increasingly studied in recent years in relation to the El Niño/Southern Oscillation (ENSO) and various other large-scale modes of atmospheric and oceanic variability. Large-scale modes of variability can sometimes be predictable several months in advance, suggesting potential for seasonal forecasting of lightning and thunderstorm activity in various regions throughout the world. To investigate this possibility, seasonal lightning activity in the world’s tropical and temperate regions is examined here in relation to numerous different large-scale modes of variability. Of the seven modes of variability examined, ENSO has the strongest relationship with lightning activity during each individual season, with relatively little relationship for the other modes of variability. A measure of ENSO variability (the NINO3.4 index) is significantly correlated to local lightning activity at 53% of locations for one or more seasons throughout the year. Variations in atmospheric parameters commonly associated with thunderstorm activity are found to provide a plausible physical explanation for the variations in lightning activity associated with ENSO. It is demonstrated that there is potential for accurately predicting lightning and thunderstorm activity several months in advance in various regions throughout the world.

Lightning activity and its association with rainfall and convective available potential energy over Maharashtra, India

This work presents the association of flash rate density (FRD) with surface air temperature, rainfall and convective available potential energy (CAPE) using satellite-based flash count grid (0.5° × 0.5°) data from 1998 to 2007 over Maharashtra, India. We investigate monthly to seasonal variations in lightning activity with rainfall and CAPE. The first peaks for FRD and rainfall found in June and July, respectively, followed by next peaks in September. The difference in peaks for FRD and rainfall of 1 month (June–July) attributed to the onset phase of summer monsoon in June (relatively less wet period favorable for more convective and lightning activity), thereafter, heavy rainfall in July over Maharashtra. The annual variations show that the September peaks for both FRD and rainfall are higher than that in June for FRD and for rainfall in July. FRD is moderately correlated with rainfall (r = 0.51 at significant level <0.0001). There is good parallelism in the variation of FRD, and CAPE as the correlation coefficient in between them is 0.78 at significant level <0.0001.

Diurnal patterns in lightning activity in northern tropical Africa

The study analyzes summertime lightning incidence data across northern tropical Africa from the TRMM satellite sensor during 1998–2011. It uses harmonic analyses to detect the spatial patterns in diurnal variations of lightning activity across the study area. The results are in conformity with previous studies examining diurnal patterns of convective weather processes in this region, with most lightning activity concentrated over land areas. The peak time of lightning activity over most of the study area was during late afternoon hours, from around 1700 to 1900 local standard time. The peak time of lightning activity was observed during early morning hours in some coastal areas, such as Cameroon, which can be a result of local-level convergence between the land and sea breeze. A general progression in the time of lightning activity from late afternoon to early evening hours was observed throughout the interior of the study area, which may be attributed to land-surface heating and associated mesoscale convective systems, and to upper-level circulation in the form of the African Easterly Jet Stream.

Variability of lightning activity in South/Southeast Asia during 1997–98 and 2002–03 El Nino/La Nina events

Impacts of the 1997–98 and 2002–03 ENSOs on total number of flashes and number of flash days from the LIS (Lightning Imaging Sensor) on board the Tropical Rainfall Measuring Mission satellite and on the average flash rate from the combined OTD (Optical Transient Detector) / LIS data are studied in South/Southeast Asia (8° –30°N, 60°–120°E) for the period 1998–2005. Also examined is the difference between the geographical distributions of these parameters in the El Nino period in 1998 and in the corresponding normal period in 1999. During the 1997–98 ENSO event, the number of flashes and average flash rate increase by 12% and 36%, respectively, during the El Nino period and during the La Nina period decrease by 22% and 5%, respectively, as compared to the corresponding normal periods. Similarly, during the 2002–2003 ENSO event, the number of flashes and average flash rate increase by 28% and 5% during the El Nino period in 2002 as compared to the corresponding normal period. The contrast in lightning activity between the El Nino and La Nina periods is more pronounced in Southeast Asia than in South Asia because of the southeastward shift in the convection activity during the ENSO events. In both regions, however, monthly variations of both total number of flashes and average flash rate are almost parallel to that of surface temperature. Although, the inverse relationship between the Indian Summer Monsoon Rainfall (ISMR) and El Nino broke down in 1997–98, the relationship between the El Nino and lightning maintains its normal increasing trend, indicating that the lightning activity is more sensitive to the convective activity than to rainfall on seasonal time scale. The total number of flashes and aerosol loading increase in the break‐period regime as compared to the monsoonal regime. The number of flash days in both ENSO events is higher in the EL Nino phase and lower in the La Nina phase as compared to their normal values in the subsequent years. Enhancement of lightning activity is mostly concentrated over land areas. Our results show that although diurnal variations in lightning activity can be related to the variations in surface temperature, convective adjustment induced by the corresponding ENSO phase needs to be considered for explaining the lightning activity variations on these longer time scales.

A harmonic model for the temporal variation of lightning activity over Africa

[1] Concise rainfall, temperature, and humidity climatologies are available for most countries, reflecting the regular annual variation of these quantities, usually with monthly resolution. Although numerous surveys of global and regional lightning activity exist, no comparable national climatologies of lightning activity are available. Annual lightning flash rate patterns for most African countries are derived here using 10 years of data from two satellite lightning detectors. These patterns can be represented accurately by annual and semiannual sinusoidal components superimposed on a mean level. The highest-average lightning activity (47.8 km−2 yr−1) occurs in the Democratic Republic of the Congo, while the lowest (0.2 km−2 yr−1) is found in Egypt. Very little lightning is observed in the Sahara, while a consistently high intensity is found throughout the tropics. There is a clear reversal in the phase of the annual component across the equator. Within the tropics the amplitude of the semiannual variation is a significant fraction of that of the annual variation but becomes less important in the subtropics.

A study of lightning activity over land and oceanic regions of India

Monthly variations of lightning activity over typical land and oceanic regions of India were examined using satellite data (OTD) for a 5-year period (1995–1999). It is noted that the nature of variation between surface air maximum temperature (T max), thunderstorm days (Thn), and lightning flash count over ER and WR showed remarkable correspondence and sensitivity with each other on monthly time scale. As we move out of winter season and enter the monsoon season, via pre-monsoon season, the WR undergoes cooling relative to the ER in the range 0.1–1.2°C. As a result, WR experiences reduction of thunder days and lowering in flash count. This decrease in T max, Thn, and flash count over WR may also be associated with relatively small values of T θw and CAPE in comparison with similar values over ER during the monsoon season. Our observation of associated reduction in Thn and lightning count per 1°C cooling in surface air maximum temperature suggests reduction of ∼3.5 thunderstorms per station and 73 flashes. Comparison of lightning flashes between pairs of coastal, oceanic, arid-zone, hilly, and island stations reveals distinct relationship between climate regime and intensity of lightning activity. We may conclude the results of this study by saying that the overhead lightning activity is a clear reflection of the status of the underlying ground-earth properties. A close and continuous monitoring of lightning activity may be considered as a need of present day scientific studies.

Significance of transient luminous events to neutral chemistry: Experimental measurements

For many years it has been suggested that transient luminous events (TLE) occurring over thunderstorms may produce significant modifications to neutral atmospheric chemistry. Some have speculated that large ionisation increases from red sprites, one type of TLE, could result in enhancements of odd nitrogen. In this study we make use of nighttime NO2 observations by the GOMOS instrument to test whether TLE are producing significant NOx enhancements in the middle atmosphere on a regional scale. Comparing regional variations of NO2 with 2–3 order of magnitude variations in lightning activity, we show that there is no significant impact of red sprites, giant jets or blue jets upon NOx levels in the stratosphere and mesosphere (20–70 km), within the detection levels of the instrument. While individual TLE may cause a local variation in NOx, these do not appear to be significant on regional scales (or beyond).

Diurnal variations in lightning activity over Swaziland as observed from Space: 1998-2006

Lightning phenomena have recently gained a lot of interest among researchers mainly due to its impact on the human and natural environment. The thermodynamics of lightning and its distribution on the landscape are, therefore, under intense investigation in many part of the world, mainly in the developed world. In this report, nine years of lightning data (January 1998 to December 2006) from the Lightning Imaging Sensor on board the Tropical Rainfall Measuring Mission (TRMM) satellite was used to analyse the diurnal frequency of lightning frequency over Swaziland, a country characterized by a complex terrain. Through geographic information systems analysis of the lightning flash counts, which was corrected for detection efficiency and instrument view time, was analysed to reveal diurnal patterns in lightning activity across the four climatic seasons and the country’s four eco-climatic (physiographic) zones. Results showed a pronounced evidence of bimodal peaks, mainly in summer (52%) and autumn (28%), during the late afternoon and evening (1400 and 2000 hours), accounting for 60% of the total hourly flashes, and a second peak during the late evening hours (2200-0000 hours), which were found to be for 27% of the hourly total. The time of maximum lightning frequently occurred mainly over the elevated areas of the Highveld) (37%), Middleveld (32%) and Lowveld (24%), resulting from updrafts caused by topographic lifting. This suggests the presence of convective development and stratiform precipitation according to the local and meso-scale circulation weather system affecting the country. The installation of a ground-based system is recommended, as this would further improve the understanding of the spatial and temporal dynamics of lightning in Swaziland. 1 Swaziland National Trust Commission, P.O. Box 100, Lobamba H107, Swaziland

Small ice crystals and the climatology of lightning

Vigorous debate still surrounds the cloud electrification process and unexplained regional variations in lightning activity. Here, we show that climatological maxima in lightning activity are associated with small effective diameter De of ice crystals near cumulonimbus cloud tops. This relationship, unlike lightning's more well‐known relationship with cloud top height, is consistent over land and ocean. Since multiple studies indicate that De is reduced by atmospheric aerosol, this relationship strengthens previous suggestions of a role for aerosols as well as dynamics in electrification. Moreover, the angular distribution of backscattered radiance shows that modest (∼10%) De decreases reflect large (∼2×) increases in the number of small (&lt;∼30 μm) particles N, a finding supported by cloud model simulations. Both relationships provide an important new test of cloud microphysics and/or electrification models.

Convective Activity Over the Indonesian Maritime Continent During CPEA-I as Evaluated by Lightning Activity and Q1 and Q2 Profiles

Lightning activity observed by the Tropical Rainfall Measuring Mission-Lightning Image Sensor (TRMM-LIS) and aerological data from the first campaign of the Coupled Process in the Equatorial Atmosphere (CPEA-I) were used to diagnose convective activity over the western part of the Indonesian maritime continent (MC) for the period between 10 April and 9 May 2004. Lightning and many deep but small convective clouds associated with low outgoing longwave radiation (OLR) dominated over large islands of the MC before the onset of a Madden Julian Oscillation (MJO) active period. During the MJO active period, a MJO cloud system composed of three super-cloud clusters (SCCs) passed eastwardly over the study area. The first SCC (SCCI) was accompanied by active lightning. After SCCI passed, lower OLR extended over a wide area including both islands and ocean, and lightning was suppressed over the large islands. Lightning activity was weaker in subsequent SCCs. Atmospheric stratification, vertical winds, the apparent heat source (Q1), and apparent moisture sink (Q2) were studied using rawinsonde observations for two areas: one over Sumatera and the other over the ocean between Sumatera and Kalimantan. Differences in vertical wind profiles between land and ocean suggest stronger onshore land-sea circulations in the break period than in the active period. Convective instability was greatest before the onset of the MJO active period over land and then weakened after onset. Over land, height of the positive peak was much higher in Q1 than in Q2 before onset. The height of the peak was comparable after onset; this change suggests that subarea-scale deep convective rain (stratiform rain) dominated before (after) the onset. These observations are consistent with variations in lightning activity. Previous observations showed that MJO cloud systems over the western Pacific have enhanced convection in their eastern portions and stratiform rain in western parts. A similar large-scale structure was maintained in the MJO cloud system over the western part of the MC, despite blocking effects by the MC on the MJO cloud system, especially in mesoscale and synoptic-scale structures.

Spatio‐temporal variability of lightning activity over the Indian region

Spatio‐temporal variability of lightning activity over the Indian land mass region (8°N–33°N, 73°E–86°E) has been studied using monthly satellite based lightning flash grid (5° × 5°) data for 5‐year (1998–2002) period. These data have been examined for depicting the annual, seasonal, and spatial distribution of the lightning activity. The study revealed the nonlinear relationship between lightning flash density and latitude on the annual timescale, and it is linked with the convective activity, large‐scale circulations, land mass gradient, and orography of the region under study. On the seasonal timescale, the nonlinear positive relationships were observed in the premonsoon and monsoon seasons whereas a bimodal variation is observed in the post‐monsoon season. The comparison of flash density with maximum surface air temperature shows the existence of nonlinear relationship between the two parameters. The approximate range of increase of flash density per 1°C rise in temperature is 20 to 44%. The lightning flash density shows a pronounced semiannual oscillation over the latitude belts 8°N–28°N.

Cloud-to-Ground Lightning: Climatological Characteristics and Relationships to Model Fields, Radar Observations, and Severe Local Storms

Abstract Data for nearly 2 million lightning flashes recorded during the 1985–86 warm seasons by the National Severe Storm Laboratory's (NSSL's) lightning strike locating network were evaluated to determine some of the climatological characteristics of cloud-to-ground lightning. Among the characteristics studied were the seasonal, diurnal, and spatial variations Of Positive and negative lightning strike activity, including flush rates, signal strength, and flash multiplicity. The lightning data were also compared to manually digitized radar data, reports of tornadoes, large hail, and damaging winds, and to analyzed 0000 UTC fields obtained from operational numerical models. An examination of the diurnal distribution of lightning revealed that peak rates occurred later than in other sections of the country, reflecting the prevalence of nocturnal convection within much of the NSSL network. An analysis of the spatial variations in lightning activity also confirmed the existence of distinct climatological reg...