Thunderstorm Frequency Research Articles

Studying the Effect of Coronal Mass Ejections and Solar Flares on Thunderstorms in the City of Mosul for Solar Cycles 23 and 24

The study of the impact of solar activity on the Earth's climate is an important matter for predicting the change of climate elements for long periods. Most research has been limited to studying the relationship of sunspots with a change in one of the climate elements. In this research, the effect of the solar activities of coronal mass ejections and solar flare on a climatic element in the troposphere, represented by thunderstorms during the winter season in the city of Mosul for the 23 and 24 solar cycles, respectively, was studied. The data on coronal mass ejections were collected from the SOHO/LASCO CME Catalog database and solar flare data were taken from the website National Oceanic and Atmosperic (NOAA). Climatic data on thunderstorms for the winter seasons from the period (1996-2019) were used from the monitoring station in the city of Mosul from the Iraqi General Authority for Meteorology and Seismic Monitoring.The parameters were analyzed using the statistical program (Minitab 19.0). The results showed that there is an inverse relationship between the monthly rates of solar activities with the monthly rate of thunderstorm frequency, with the exception of the rising phase of the solar cycle 24 for the time period (2008-2013), where the results showed the existence of a positive relationship between them

Effects of convective available potential energy, temperature and humidity on the variability of thunderstorm frequency over Bangladesh

Effects of convective available potential energy, temperature and humidity on the variability of thunderstorm frequency over Bangladesh

Compensating Customers for Power Outages: A Bad Regulatory Policy?

Few people doubt that the United States will continue experiencing long‐lasting, highly damaging electric power outages—like outages from Superstorm Sandy, Hurricane Maria in Puerto Rico, the Texas Blackout, record‐breaking heat waves causing wildfires and infrastructure damage, and more tornadic activity and severe hurricanes in Florida and other coastal states. Many weather experts believe that hurricane strength, precipitation intensity, thunderstorm frequency, and winter storm activity—all partially attributed to climate change—will continue to escalate in the future. These occurrences will likely lead to more frequent and longer‐lasting power outages with the potential to inflict significant harm on businesses, individuals and local economies.

The Trends of Warm‐Season Thunderstorm and Lightning Days in China and the Influence of Environmental Factors

AbstractPrevious studies indicated that numbers of meso‐micro scale severe convective weather exhibited a significant decrease over China's mainland in the past decades. However, the possible mechanism of the decrease has not been well understood. This paper analyzes the changes in frequency of thunderstorm and lightning days using an updated data set of denser national observational stations and theirs links to the atmospheric circulation and regional environmental factors. The results confirm the highly significant decreasing trend of frequency of thunderstorm and lightning days during 1961–2013, with the decreasing rates of −2.6 days/10 years and −6.5 days/10 years in the warm season, respectively. The decrease of geopotential height difference between south and north, the weakening of westerly jet strength at 200 hPa and the decline of zonal wind speed of high level are found to be the direct reasons for the wide‐spread decrease of thunderstorm and lightning days across the country. Meanwhile, there is a significant positive correlation between thunderstorm days and convective available potential energy (CAPE), indicating a reduction of potential atmospheric instability accompanying the decline of thunderstorm days especially in the south of China. The decrease in the relative humidity at the lower troposphere, the weakening of 0–6 km vertical wind shear and the accompanying slackening of actual convective activity, may have also contributed to the downward trends of the severe convective weather. Our analysis shows a strong link of the decreasing thunderstorm and lightning days to the long‐term changes of the atmospheric circulation and environmental factors. Further investigation is needed to examine what have driven the changes of the environmental factors over the time period.

Global climatology and trends in convective environments from ERA5 and rawinsonde data

Globally, thunderstorms are responsible for a significant fraction of rainfall, and in the mid-latitudes often produce extreme weather, including large hail, tornadoes and damaging winds. Despite this importance, how the global frequency of thunderstorms and their accompanying hazards has changed over the past 4 decades remains unclear. Large-scale diagnostics applied to global climate models have suggested that the frequency of thunderstorms and their intensity is likely to increase in the future. Here, we show that according to ERA5 convective available potential energy (CAPE) and convective precipitation (CP) have decreased over the tropics and subtropics with simultaneous increases in 0–6 km wind shear (BS06). Conversely, rawinsonde observations paint a different picture across the mid-latitudes with increasing CAPE and significant decreases to BS06. Differing trends and disagreement between ERA5 and rawinsondes observed over some regions suggest that results should be interpreted with caution, especially for CAPE and CP across tropics where uncertainty is the highest and reliable long-term rawinsonde observations are missing.

Development of novel hybrid machine learning models for monthly thunderstorm frequency prediction over Bangladesh

Thunderstorm frequency (TSF) prediction with higher accuracy is of great significance under climate extremes for reducing potential damages. However, TSF prediction has received little attention because a thunderstorm event is a combination of intricate and unique weather scenarios with high instability, making it difficult to predict. To close this gap, we proposed two novel hybrid machine learning models through hybridization of data pre-processing ensemble empirical mode decomposition (EEMD) with two state-of-arts models, namely artificial neural network (ANN), support vector machine for TSF prediction at three categories over Bangladesh. We have demarcated the yearly TSF datasets into three categories for the period 1981–2016 recorded at 28 sites; high (March–June), moderate (July–October), and low (November–February) TSF months. The performance of the proposed EEMD-ANN and EEMD-SVM hybrid models was compared with classical ANN, SVM, and autoregressive integrated moving average. EEMD-ANN and EEMD-SVM hybrid models showed 8.02–22.48% higher performance precision in terms of root mean square error compared to other models at high-, moderate-, and low-frequency categories. Eleven out of 21 input parameters were selected based on the random forest variable importance analysis. The sensitivity analysis results showed that each input parameter was positively contributed to building the best model of each category, and thunderstorm days are the most contributing parameters influencing TSF prediction. The proposed hybrid models outperformed the conventional models where EEMD-ANN is the most skillful for high TSF prediction, and EEMD-SVM is for moderate and low TSF prediction. The findings indicate the potential of hybridization of EEMD with the conventional models for improving prediction precision. The hybrid models developed in this work can be adopted for TSF prediction in Bangladesh as well as different parts of the world.

Two hundred years of thunderstorms in Oxford

Meteorological records commenced at the Radcliffe Observatory in Oxford in 1772. Detailed records of thunderstorm occurrence are available between 1828 and 1986; since 1986 a reliable private record of thunder frequency from Oxford has been used to extend the record to 2019, forming a record of almost 200 years of thunderstorm frequency for the city – a record probably unique anywhere in the world. This newly digitised record is examined for long-term (decadal) trends in thunderstorm frequency, and by Lamb Weather Type. Comparisons are made with other long-period records from West London, around 75km southeast of Oxford. Reasons to account for the marked reduction in thunderstorm frequency in the last decade are suggested.

The differing role of weather systems in southern Australian rainfall between 1979\u20131996 and 1997\u20132015

Most of the rainfall in southern Australia is associated with cyclones, cold fronts, and thunderstorms, and cases when these weather systems co-occur are particularly likely to cause extreme rainfall. Rainfall declines in some parts of southern Australia during the cool half of the year in recent decades have previously been attributed to decreases in the rainfall from fronts and/or cyclones, while thunderstorm-related rainfall has been observed to increase, particularly in the warm half of the year. However, the co-occurrence of these systems, particularly the co-occurrence of cyclones or fronts with thunderstorms, can be very important for rainfall in some areas, particularly heavy rainfall, and changes in the frequency of these combined weather systems have not been previously assessed. In this paper we show that the majority of the observed cool season rainfall decline between 1979–1996 and 1997–2015 in southeast Australia is associated with a decrease in the frequency of fronts and cyclones that produce rainfall, while there has simultaneously been an increase in the frequency of cold fronts and thunderstorms that do not produce rainfall in some regions. Thunderstorm rainfall has increased in much of southern Australia, particularly during the warm half of the year, including an increase in rainfall where a thunderstorm environment occurs at the same time as a cyclone or front.

Review article: A comprehensive review of datasets and methodologies employed to produce thunderstorm climatologies

Abstract. Thunderstorm and lightning climatological research is conducted with a view to increasing knowledge about the distribution of thunderstorm-related hazards and to gain an understanding of environmental factors increasing or decreasing their frequency. There are three main methodologies used in the construction of thunderstorm climatologies: thunderstorm frequency, thunderstorm tracking or lightning flash density. These approaches utilise a wide variety of underpinning datasets and employ many different methods ranging from correlations with potential influencing factors and mapping the distribution of thunderstorm day frequencies to tracking individual thunderstorm cell movements. Meanwhile, lightning flash density climatologies are produced using lightning data alone, and these studies therefore follow a more standardised format. Whilst lightning flash density climatologies are primarily concerned with the occurrence of cloud-to-ground lightning, the occurrence of any form of lightning confirms the presence of a thunderstorm and can therefore be used in the compilation of a thunderstorm climatology. Regardless of approach, the choice of analysis method is heavily influenced by the coverage and quality (detection efficiency and location accuracy) of available datasets as well as by the controlling factors which are under investigation. The issues investigated must also reflect the needs of the end-use application to ensure that the results can be used effectively to reduce exposure to hazard, improve forecasting or enhance climatological understanding.

Evaluating the impact of climate change in threshold values of thermodynamic indices during pre-monsoon thunderstorm season over Eastern India

The present study analyses thermodynamic indices variation over three sites of eastern Indian region: Bhubaneswar, Kolkata and Ranchi, associated with pre-monsoon thunderstorms for 20-year period (1987–2006) for Bhubaneswar and Kolkata and 15 years (1996–2010) for Ranchi. All three sites are showing a rise in humidity over the period, unveiling the climate change over the region. We evaluated the threshold values of various thermodynamic indices for periods of 5-year intervals at each site based on skill score analysis. The indices associated with potential, convective, latent instability and moisture are showing varying threshold values over all the sites, and some of the indices are showing a definite increase/decrease in these threshold values. All three sites are showing a decrease in thunderstorm frequency over the study period. The work identifies the thermodynamic indices, which tend to capture the global warming impact in the threshold values by either showing an increase or decrease with the time at each site. The results advocate that for a long-term analysis of thermodynamic indices, the threshold values may change from one period to another.

Spatiotemporal variations of thunderstorm frequency and its prediction over Bangladesh

Understanding the spatiotemporal variations of thunderstorm (TS) frequency over Bangladesh under the changing climate is of immense importance but remains a challenging task due to the lack of persistent and reliable weather data set. This study demonstrates a statistically significant increasing trend in the occurrence of monthly, seasonal, and annual TS frequencies except for decadal periods across Bangladesh during the past 6 decades. Further, land use influences and seasonal variabilities in convective available potential energy (CAPE) are also explored in various regions to understand the spatial variabilities among different parts in Bangladesh. The results show the highest occurrence of TS in monsoon and the lowest occurrence in the winter season. The results of Ward’s Hierarchical Cluster analysis (WHCA) illustrate four clusters for the whole country, where the higher TS frequency was observed in northeastern and northern regions and the lower in the southern part of Bangladesh due to the variation of CAPE and development of the low-pressure system. The occurrence of TS frequency maxima and lower coefficients of variation are found in the pre-monsoon and monsoon seasons. The variation coefficient of the winter season is high, while the pre-monsoon season is low. The results of Mann–Kendall (MK) and Spearman’s rho (SR) tests reveal the highest increase and decrease trends in M. Court and Tangail stations. The ARIMA model outcomes are consistent with the findings of MK and SR tests. Overall, this study reveals that elevated CAPE and climate warming may be reasoned of increasing the TS frequency over Bangladesh.

Thunderstorm Classification Functions Based on Instability Indices and GNSS IWV for the Sofia Plain

Bulgaria is a country with a high frequency of hail and thunderstorms from May to September. For the May–September 2010–2015 period, statistical regression analysis was applied to identify predictors/classification functions that contribute skills to thunderstorm forecasting in the Sofia plain. The functions are based on (1) instability indices computed from radiosonde data from Sofia station F1, and (2) combination of instability indices and Integrated Water Vapor (IWV), derived from the Global Navigation Satellite System (GNSS) station Sofia-Plana, F2. Analysis of the probability of detection and the false alarm ratio scores showed the superiority of the F2 classification function, with the best performance in May, followed by June and September. F1 and F2 scores were computed for independent data samples in the period 2017–2018 and confirmed the findings for the 2010–2015 period. Analysis of IWV and lightning flash rates for a multicell and supercell thunderstorm in June and July 2014 showed that the monthly IWV thresholds are reached 14.5 and 3.5 hours before the thunderstorm, respectively. The supercell IWV peak registered 40 min before the thunderstorm, followed by a local IWV minimum corresponding to a peak in the flash rate. In both cases, an increase of IWV during severe hail was registered, which is likely related to the hydrometeor contribution to GNSS path delay. The results of this study will be integrated into the Bulgarian Integrated NowCAsting tool for thunderstorm forecasting in the warm/convective season.

Lightning flash density in Europe based on 10 years of ATDnet data

Abstract The first decadal lightning flash climatology for Europe is presented using ATDnet long-range lightning detection network operated by the Met Office. More than 148 million lightning flashes were detected by ATDnet in the study area between 2008 and 2017. The dataset contains up to 90% of cloud-to-ground flashes and 25% of cloud flashes in Europe during the study period. All maps were computed with a spatial resolution of 0.2°. The annual flash density was between 0.5 and 3.0 flashes per km−2 y−1 in most of Europe with a maximum of 7.8 flashes km−2 y−1 in the northeast of Italy. Most of continental Europe experienced 20–40 thunderstorm days annually but a small area on the border of Armenia and Turkey experienced up to 87.6 thunderstorm days. This number exceeds previous estimates of European maximum thunderstorm frequency. The North Atlantic Ocean had only up to 10 thunderstorm days and 0.1 flash km−2 y−1. Flash density per thunderstorm day varied from 0.1 fl km−2 in the northeast of Italy. Occasional intense storms were found to happen even in areas without regular thunderstorm activity, including the oceans to the north of the Arctic Circle. Most of the study area had a mid-latitude specific summer peak in lightning activity whereas the Mediterranean experienced an autumn maximum. From March to August, most of the lightning in Europe occurred over land whereas from September to February it was concentrated over the Mediterranean. The highest lightning frequency over land was observed during the afternoon hours and the lowest frequency at night. At sea the diurnal distribution of lightning peaked either at night or in the morning hours.

Frequency of severe thunderstorms across Europe expected to increase in the 21st century due to rising instability

We show that the frequency of damaging convective weather events including lightning, hail and severe wind gusts will likely increase over Europe until the end of this century. We apply a set of additive regression models to an ensemble of 14 regional climate simulations and find that convective instability will increase as a result of rising humidity near the earth’s surface. Even though a slight decrease in thunderstorm occurrence in southwestern and southeastern Europe is projected, the probability of severe weather will increase throughout Europe, in particular for very large hail. It might be expected that Arctic amplification would lead to a weaker jet stream and, thus lower vertical wind shear, but we find instead that the jet changes little or even increases in situations with convective instability. To cope with the rising hazard probabilities, risk models will need to be adapted, while investment in sturdier structures, like the use of hardened glass in greenhouses or solar panels, will become more cost-effective. Furthermore, the need will grow to advise the public on loss prevention by taking precautionary measures as storms approach.

Satellite-based observation of lightning climatology over Nepal

The lightning climatology over Nepal is analysed in detail for the first time. For the analysis, we utilised the satellite-based lightning imaging sensor data for the period from 1998 to 2013. A comparison of these climatological results is also performed with two ground-based lightning detection networks, namely, the World Wide Lightning Location Network and the Global Lightning Network for 3 yr from 2011 to 2013. On analysing the data obtained from the three sources, we conclude that the months of April and May are extremely vulnerable in the perspective of lightning hazards in Nepal, in contrast to the results reported previously which indicated that the maximum lightning activity occurred in the month of June. The central and eastern regions of the country receive the majority of lightning strikes during the months of April and May. The present finding is supported by the thunderstorm frequency data obtained from the disaster Information Management System, Nepal and also from thunder-day data from NOAA.

Global warming and warning

Evidence that the earth’s temperature is increasing is provided by warming of the oceans, the melting of glaciers, rising sea levels and the diminished snow cover in the Northern Hemisphere. Climate change is associated with the intensity and frequency of precipitation, thunderstorms, sandstorms, and extreme weather events, such as heat waves, droughts, blizzards, floods, and hurricanes. Air pollution, especially increased carbon dioxide concentrations, is the driving power of the earth’s warming through the greenhouse effect. Wildfires and deforestation also contribute [...]

Thunderstorm frequency distribution and associated convective mechanisms over Pakistan

This study investigates the frequency distribution of thunderstorm activity over Pakistan via the analysis of two convective parameters, i.e., convective available potential energy (CAPE) and convective inhibition (CIN). The climatology and trends of thunderstorm frequency, CAPE, and CIN have been analyzed, based on seasonal and annual timescales, by using station and reanalysis datasets. Thirty-eight years (1979–2016) data of monthly thunderstorm days for 54 meteorological stations, well-distributed over the country, have been utilized in this study. Those meteorological stations which constitute core region of thunderstorm frequency are identified. Our analysis showed that the mountainous and sub-mountainous areas of Pakistan, particularly in upper half of the country, are at the top with the maximum thunderstorm activity on both seasonal and annual timescales. Pre-monsoon (April–June) and monsoon (July–September) are most vulnerable seasons to the development of thunderstorms. It is also observed that most of the stations exhibit an increase in the thunderstorm days during winter (December–March) and decrease during pre-monsoon, monsoon, and post-monsoon (October–November) seasons. Interestingly, core regions of CAPE and thunderstorm frequency almost coincide with region of low CIN. However, trends in CAPE do not explain the variability and trends of thunderstorm frequency over the whole study area explicitly. At some stations, trends in CAPE are increasing in contrast to thunderstorm frequency trends. We showed, in particular, that the increasing trend of CIN is a likely reason for decreasing trends of thunderstorm frequency over Pakistan. In total, 17 stations are identified to be the most vulnerable to thunderstorm activity over the country.

Exploratory analysis of lightning-ignited wildfires in the Warren Region, Western Australia

An exploratory analysis of lightning-ignited wildfire data for the Warren Region of Western Australia was carried out for the period from April 1976 to December 2016. Temporal patterns in the series were examined in terms of characterizing the seasonal cycle, and detecting long-term trends and changes in seasonality over time. A generalized additive modelling approach was used to ensure that temporal features were determined by the data rather than a priori assumed mathematical forms (e.g. linear or low-order polynomial functions). The spatial organization of the data was evaluated using concepts from the theory of stochastic point processes. Results indicate a strong seasonality in the monthly lightning ignition series, the presence of a long-term trend and an interaction between trend and seasonality. There is also strong evidence of spatial variation in the number of ignitions per unit area in terms of location and distance from nearest ignition. Within the Warren Region, observation platforms for fire detection and reporting protocols have remained stable over the period of record, and changes in land use are unlikely to have altered the pattern of lightning ignition. Thus, the above results might reflect an interplay between: landscape attributes (e.g. vegetation classes, elevation, slope, aspect); changes in rainfall and fuel moisture; changes in fuel management practices; and, perhaps, an increase in the frequency of dry thunderstorms and fire weather conditions.

Spatial and temporal variations in the frequency of thunderstorm days over India

AbstractThe present study investigates the spatial and temporal variations in the frequency of thunderstorm days over India, based on data from 294 observatory stations for four overlapping 30‐year time periods: 1951–1980, 1961–1990, 1971–2000 and 1981–2010. Analysis of the data revealed a significant decreasing trend in thunderstorm frequency over India. Relative to the 1951–1980 time period, there has been a net decrease of 34% in the frequency of thunderstorm days during the 1981–2010 period. Seasonal analysis confirms, unsurprisingly, that the maximum thunderstorm frequency occurs during monsoon season (June–September), with the lowest frequency occurring over the winter season (January–February). June is the month with the highest number of thunderstorm days, while December has the lowest. The greatest number of thunderstorms is observed over northeastern India, and the smallest number in the western parts of the country. Regional investigations show a wide variability in the occurrence of thunderstorms over space and time. The frequency of thunderstorm days over the mountains is much higher than over the plains at the same latitude.

Investigating the relationship between the frequency of thunderstorms and temperature trend in Mashhad

Investigating the relationship between the frequency of thunderstorms and temperature trend in Mashhad