Increase In Lightning Activity Research Articles

Influence of the Super El Niño event during 2015/2016 on the aerosol properties and lightning activity in subtropical South America

This work investigates the impact of ENSO on aerosols and lightning activity in subtropical South America (SSA). An analysis of the interannual variability of Aerosol Optical Depth (AOD), Ångström Exponent (AE) and different cloud parameters using MODIS satellite datasets and the lightning activity based on the lightning observations from the World Wide Lightning Location Network was performed. High positive AE, AOD anomalies and high lightning activity were found in the northeastern region of SSA during the Super El Niño event during 2015/2016 in latter spring and summer. The Pearson correlation coefficients between these aerosol parameters and monthly discharges were higher than 0.7 in the northeastern region during the Super El Niño. These positive correlations, which have been widely reported in previous studies, were explained considering the vegetation cover, consisting mainly of subtropical forests in the northeastern region of SSA, and the increase in rainfall during El Niño in this area in spring and summer. The increases in AOD and AE during latter spring and summer in the northeastern region were therefore related to the release of biological aerosols and to aerosols emission mechanisms independent of the background aerosol concentration, respectively. The increase in lightning activity was related to the role of these released aerosols as ice nuclei particles and/or as cloud condensation nuclei, affecting cloud properties and thus the lightning activity. The results reported in this work show the effect of the Super El Niño on aerosol and lightning activity and, in this way on aerosol-cloud interactions.

Cloud-to-Ground Lightning in Cities: Seasonal Variability and Influential Factors

AbstractUrban-induced land use changes have a significant impact on local weather patterns, leading to increased hydro-meteorological hazards in cities. Despite substantial threats posed to humans, understanding atmospheric hazards related to urbanisation, such as thunderstorms, lightning, and convective precipitation, remains unclear. This study aims to analyse seasonal variability of cloud-to-ground (CG) lightning in the five large metropolitans in Bangladesh utilising six years (2015–2020) of Global Lightning Detection Network (popularly known as GLD360) data. It also investigates factors influencing CG strokes. The analysis revealed substantial seasonal fluctuations in CG strokes, with a noticeable increase in lightning activity during the pre-monsoon months from upwind to metropolitan areas across the five cities. Both season and location appear to impact the diurnal variability of CG strokes in these urban centres. Bivariate regression analysis indicated that precipitation and particulate matter (PM) significantly influence lightning generation, whilst population density, urban size, and mean surface temperature have negligible effects. A sensitivity test employing a random forest (RF) model underscored the pivotal role of PM in CG strokes in four of the five cities assessed, highlighting the enduring impact of extreme pollution on lightning activity. Despite low causalities from CG lightning, the risk of property damage remains high in urban environments. This study provides valuable insights for shaping public policies in Bangladesh, a globally recognised climate hotspot.

Response of photosynthesis and electrical reactions of wheat plants upon the action of magnetic fields in the Schumann resonance frequency band

ABSTRACT Alternating magnetic fields (MF) with Schumann resonance frequencies accompanied the development of living organisms throughout evolution, but today it remains unclear whether they can have a special biological effect in comparison with surrounding non-resonant frequencies. This work shows some stimulating effect of extremely low-frequency MFs on morphometric parameters and the activity of physiological processes in wheat (Triticum aestivum L.). It is shown that the MF effect is more pronounced for transient processes – photosynthesis reactions and changes in electrical potential caused by turning on light. For light-induced electrical reactions, the dependence of the severity of the effect on the frequency of the applied MF was demonstrated. It is shown that the most pronounced effect occurs in the 14.3 Hz field, which corresponds to the second harmonic of the Schumann resonance. The predominant sensitivity of signal-regulatory systems gives reason to assume the influence of MFs with Schumann resonance frequencies on the interaction of plants with environmental factors under conditions of a changed electromagnetic environment. Such conditions can occur, for example, with an increase in lightning activity caused by climate change, which serves as the basis for the generation of Schumann resonances, and with the development of artificial ecosystems outside the Earth’s atmosphere.

Responses of the AC/DC Global Electric Circuit to Volcanic Electrical Activity in the Hunga Tonga‐Hunga Ha'apai Eruption on 15 January 2022

AbstractResponses of the AC and DC global electric circuits (GECs) to the large eruption of the Hunga Tonga‐Hunga Ha'apai (HT‐HH) volcano on 15 January 2022 are discussed. The AC‐related investigation is based on Schumann resonance (SR) measurements from six stations on four continents. The DC‐related investigation utilizes atmospheric electric field (potential gradient, PG) measurements from six recording stations in Europe and the USA. According to data from the GLD360 and WWLLN lightning detection networks, the peak lightning stroke rate, 83/s, was dominated by negative polarity lightning, but the distributions of positive and negative lightning discharges in latitude and longitude around the volcano differed. A global intensification of SR is apparent in connection with the enhanced lightning activity caused by the eruption. SR data‐based results confirm that the lightning activity in the eruption dominated the naturally occurring global activity for a period of about 1 hr. The highly localized increase in lightning activity over HT‐HH was a unique point source of SR excitation. PG measurements suggest that impulse‐like charging of the DC GEC, by ∼15%, via negative cloud‐to‐ground lightning strokes took place twice during the eruption. A time constant of 7 or 8 min has been inferred for near‐surface PG changes due to these enhancements. This could be the first direct measurement of the time constant of the GEC near the Earth's surface, as well as the first observation of the direct charging of the DC GEC by a unique atmospheric electrified source.

Significantly Increased Lightning Activity Over the Tibetan Plateau and Its Relation to Thunderstorm Genesis

AbstractUnder the context of global warming, we identified a significant increase in lightning activity in the last two decades over the Tibetan Plateau (TP), the highest plateau on earth, based on two data sets. The largest rise of lightning activity was found over the region with high lightning density represented by the eastern TP at a rate of 0.072 ± 0.069 fl km−2 yr−1 during 1996–2013 from Optical Transient Detector/Lightning Imaging Sensor. World Wide Lightning Location Network data also showed a remarkable increase in lightning strokes during 2010–2019 in the maximum lightning density region, while the change was insignificant in the low lightning density region. Further investigations revealed that most of the TP region experienced a significant increase in thunderstorm frequency, which was responsible for the increase in lightning activity, rather than an increase in thunderstorm intensity. Increased lightning activity implies a potential risk to human beings and the fragile ecosystem over the TP in a warmer climate.

Lightning Variability in Dynamically Downscaled Simulations of Alaska’s Present and Future Summer Climate

AbstractLightning is a key driver of wildfire activity in Alaska. Quantifying its historical variability and trends has been challenging because of changes in the observational network, but understanding historical and possible future changes in lightning activity is important for fire management planning. Dynamically downscaled reanalysis and global climate model (GCM) data were used to statistically assess lightning data in geographic zones used operationally by fire managers across Alaska. Convective precipitation was found to be a key predictor of weekly lightning activity through multiple regression analysis, along with additional atmospheric stability, moisture, and temperature predictor variables. Model-derived estimates of historical June–July lightning since 1979 showed increasing but lower-magnitude trends than the observed record, derived from the highly heterogeneous lightning sensor network, over the same period throughout interior Alaska. Two downscaled GCM projections estimate a doubling of lightning activity over the same June–July season and geographic region by the end of the twenty-first century. Such a substantial increase in lightning activity may have significant impacts on future wildfire activity in Alaska because of increased opportunities for ignitions, although the final outcome also depends on fire weather conditions and fuels.

The effect of El Nino and La Nina on lightning activity: its relation with meteorological and cloud microphysical parameters

The decadal variation of lightning activity over Northeast India (NEI) from the year 2002 to 2011 is studied with the help of satellite-based lightning imaging sensor (LIS) data. An anomalous 56 % increase in lightning activity is observed in the year 2010 with respect to the previous years. To investigate the reason behind this increase, the LIS data are analyzed with several meteorological and cloud microphysical parameters. These parameters are convective sources of cloud ice, cloud top temperature, surface temperature, convective precipitation rate and total ice water content and convective available potential energy. On a synoptic scale, the period of anomalous lightning activity could be related to the development of an El Nino event at the middle of 2009 that broke down in the early months of the next year with a rapid transition to La Nina by August 2010. Analyses expose that El Nino Southern Oscillation might have diversely modified the local meteorological and cloud microphysical parameters. It comes out that this rapid transition from El Nino to La Nina condition could be the possible reason behind the dramatic increase in lightning activity, which was not previously documented over NEI.

Climate indicators for lightning over sea, sea–land mixed and land‐only surfaces in India

ABSTRACTIn this article, we investigate indicators for lightning activity by analysing the data of surface heat flux, Bowen ratio (ratio of sensible to latent heats) and cloud base height for a period of 16 years (1998–2013) over Indo‐Gangetic Plain (IGP) (25°–27°N, 80°–88°E), Indian land excluding IGP (8°–36°N, 68°–98°E) and 10 years (2000–2009) over Indian seas [Arabian Sea (5°–20°N, 65°–80°E) + Bay of Bengal (5°–20°N, 80°–98°E)]. Lightning activity varies with the surface heat flux, Bowen ratio and cloud base height over India. Over Indian land, annual lightning flash counts are found to be more by 32 and 24% than those over IGP and Indian seas, respectively. Total heat flux (sensible + latent) and lightning flash counts show a strong correlation coefficient of 0.75 for Indian land and 0.73 for IGP relative to that of Bowen ratio with lightning flash count (0.63 for Indian land and 0.19 for IGP). Hence, the total heat flux represents the best parameter for describing lightning activity over IGP and Indian land. Bowen ratio ≥1 in pre‐monsoon increases lightning flash counts over IGP and Indian land. Cloud base height (a measure of moisture) and lightning flash counts show values in the order as Indian land > Indian seas > IGP. Geographic asymmetry of Indian land, IGP and Indian seas drive the continental and sea surface–atmosphere interactive processes that corroborate: (1) asymmetric synoptic scale delivery of moisture to Indian land and IGP from Indian seas revises the Bowen ratio, cloud base height and lightning activity, (2) increase in lightning activity with the total heat flux over Indian land and (3) enhance the lightning activity with the cloud base height/liquid condensation level.

Cloud — Aerosol interaction during lightning activity over land and ocean: Precipitation pattern assessment

The present study attempts to identify the land - ocean contrast in cloud - aerosol relation during lightning and non-lightning days and its effect on subsequent precipitation pattern. The thermal hypothesis in view of Convective Available Potential Energy (CAPE) behind the land - ocean contrast is observed to be insignificant in the present study region. The result shows that the lightning activities are significantly and positively correlated with aerosols over both land and ocean in case of low aerosol loading whereas for high aerosol loading the correlation is significant but, only over land. The study attempts to comprehend the mechanism through which the aerosol and lightning interact using the concept of aerosol indirect effect that includes the study of cloud effective radius, cloud fraction and precipitation rate. The result shows that the increase in lightning activity over ocean might have been caused due to the first aerosol indirect effect, while over land the aerosol indirect effect might have been suppressed due to lightning. Thus, depending on the region and relation between cloud parameters it is observed that the precipitation rate decreases (increases) over ocean during lightning (non-lightning) days. On the other hand during non-lightning days, the precipitation rate decreases over land.

The impact of the Western Ghats on lightning activity on the western coast of India

The effect of the Western Ghats on the lightning activity across the west coast of India around the coastal metropolitan city of Mumbai during the 1998–2012 period is investigated using data from the Lightning Imaging Sensor (LIS) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. A land–sea contrast of an order of magnitude in the lightning activity is observed even in a small area across the western coast of India. The shape of a zone of high lightning activity formed almost parallel to the Western Ghats during the onset and withdrawal phases of monsoon, strongly suggests the effect of the Western Ghats in its formation. Seasonal variation of the lightning activity in this area and also in each of its four equal sectors (two each over the Arabian Sea and over land) is bi-annual with one peak each in the onset (May/June) and withdrawal months (September/October) of monsoon and a sharp dip to very low values during the monsoon months (July/August) of maximum seasonal rainfall. The lightning activity in each sector is found to increase over the 1998–2012 period. However, the increase in lightning activity over the sector containing Mumbai is found to be greater during the pre- and post-monsoon periods and smaller during the monsoon period as compared to an identical sector immediately south of it.

The lightning activity associated with the dry and moist convections in the Himalayan Regions

AbstractLightning activity in the dry environment of northwest India and Pakistan (NW) and in the moist environment of northeast India (NE) has been examined from the Optical Transient Detector and Lightning Imaging Sensor data obtained from the Tropical Rainfall Measuring Mission satellite during 1995–2010. In the NW region, seasonal variation of flash rate is annual with a maximum in July but is semi‐annual with a primary maximum in April and a secondary maximum in September, in the NE region. On diurnal scale, flash rate is the maximum in the afternoons, in both the NE and NW regions. The correlation of flash rate with convective parameters, viz. surface temperature, convective available potential energy (CAPE) and outgoing long‐wave radiation is better with convective activity in the NW than in the NE region. Mean value of aerosol optical depth at 550 nm is ~ 26% higher and is highly correlated with flash rate in NW as compared to that in NE. Results indicate that CAPE is ~ 120 times more efficient in NW than in the NE region for production of lightning. The empirical orthogonal function analysis of flash rate, surface temperature, and CAPE shows that variance of lightning activity in these regions cannot be fully explained by the variance in the surface temperature and CAPE alone, and that some other factors, such as orographic lifting, precipitation, topography, etc., may also contribute to this variance in these mountainous regions. Further, the increase in CAPE due to orographic lifting in the Himalayan foothills in the NE region may contribute to ~ 7.5% increase in lightning activity. Relative roles of the thermally induced and moisture‐induced changes in CAPE are examined in these regions. This study merely raises the questions, and that additional research is required for explaining the fundamental reasons for the reported observations here.

Aerosol indirect effect on tropospheric ozone via lightning

Tropospheric ozone (O3) is a pollutant and major greenhouse gas and its radiative forcing is still uncertain. Inadequate understanding of processes related to O3 production, in particular those natural ones such as lightning, contributes to this uncertainty. Here we demonstrate a new effect of aerosol particles on O3production by affecting lightning activity and lightning‐generated NOx (LNOx). We find that lightning flash rate increases at a remarkable rate of 30 times or more per unit of aerosol optical depth. We provide observational evidence that indicates the observed increase in lightning activity is caused by the influx of aerosols from a volcano. Satellite data analyses show O3is increased as a result of aerosol‐induced increase in lightning and LNOx, which is supported by modle simulations with prescribed lightning change. O3production increase from this aerosol‐lightning‐ozone link is concentrated in the upper troposphere, where O3 is most efficient as a greenhouse gas. In the face of anthropogenic aerosol increase our findings suggest that lightning activity, LNOx and O3, especially in the upper troposphere, have all increased substantially since preindustrial time due to the proposed aerosol‐lightning‐ozone link, which implies a stronger O3 historical radiative forcing. Aerosol forcing therefore has a warming component via its effect on O3 production and this component has mostly been ignored in previous studies of climate forcing related to O3and aerosols. Sensitivity simulations suggest that 4–8% increase of column tropospheric ozone, mainly in the tropics, is expected if aerosol‐lighting‐ozone link is parameterized, depending on the background emission scenario. We note, however, substantial uncertainties remain on the exact magnitude of aerosol effect on tropospheric O3 via lightning. The challenges for obtaining a quantitative global estimate of this effect are also discussed. Our results have significant implications for understanding past and projecting future tropospheric O3forcing as well as wildfire changes and call for integrated investigations of the coupled aerosol‐cloud‐chemistry system.

Lightning characteristics over central India during Indian summer monsoon

Lightning data, of last 12 years (1998 to 2009) measured by TRMM satellite, over central India (Lat, 15.5° N to 25.5° N and Lon, 75° E to 85° E) during Indian summer monsoon (July, August and September) have been analyzed to study the effect of Convective Available Potential Energy (CAPE) on lightning activity during monsoon and time evolution of lightning over this region. Analysis suggests that CAPE plays important role in the lightning activity during monsoon over central India. The CAPE shows no significant change during transition of monsoon from break to active or from active to break phase. Time evolution of lightning over central India, in the last 12 years shows a systematic increase in lightning activity over central India and this increase in lightning over this region is attributed to the increase in CAPE. The lightning data show a typical diurnal pattern with a strong peak at 1700 h local time (LT). Such a typical diurnal variation of lightning and its good positive correlation with CAPE suggest that the monsoon convections over central India are not purely of oceanic based type but they are combination of oceanic and continental type convections.

The 1997–98 El Nino event and related wintertime lightning variations in the southeastern United States

The El Nino Southern Oscillation (ENSO) is a climate anomaly responsible for worldwide weather impacts ranging from droughts to floods. In the United States, warm episode years are known to produce above normal rainfall along the Southeast U.S. Gulf Coast and into the Gulf of Mexico, with the greatest response observed in the October–March period of the warm episode year. The 1997–98 warm episode is notable for being the strongest event since 1982–83. With the recent launch of a lightning sensor on NASA's Tropical Rainfall Measuring Mission (TRMM) in November 1997 and the detailed coverage of the U.S. National Lightning Detection Network (NLDN), such interannual changes in lightning activity can be examined with far greater detail than ever before. For the 1997–98 ENSO event the most significant year‐to‐year changes in lightning frequency worldwide occurred along the Gulf Coast and within the Gulf of Mexico basin during the Northern Hemisphere winter. Within a broad swath across the northern Gulf of Mexico basin there is a 100–150% increase in lightning days year‐to‐year (a peak of 33 days in the winter of 1997–98 vs. only 15 days or fewer in both the 1996–97 and 1998–99 winter). In addition, there is a nearly 200% increase in lightning hours (a peak of 138 hours in 1996–97 vs. 50 hours in both 1996–97 and 1998–99). The increase in lightning activity during ENSO occurs in association with a 100% increase in the number of synoptic scale cyclones that developed within or moved through the Gulf basin. The primary variables controlling these enhancements in thunderstorm activity are the position and strength of the jet stream.