Investigación de las estructuras eléctricas y líderes de rayos en tormentas : aportaciones a las condiciones de inicio de rayos gamma terrestres

This thesis presents a characterization of the charge structures of thunderstorms and lightning leader development, and their relationship with the emissions of terrestrial gamma ray flashes (TGFs). The results include a detailed view of thundercloud charge distributions, their altitude range and life cycle evolution. The altitude of charge centers and the identification of complex charge structures have also been included. Additionally, the developments of the lightning leaders, their altitudes of initiation, polarities, and spatial and temporal characteristics across different seasons are studied by analyzing the lightning leader signature from a Lightning Mapping Array (LMA), which was installed also for the first time in the tropics during this work. According to the characterization of charge structures, a lightning leader model is developed. The main goal of the model is to analyze the potential and the electric field stress expected during lightning discharge simulations. In addition, simulations about TGF emissions obtained from particle interactions have been included. In this case, the LEPTRACK program is used along with the main results of the leader model in order to analyze the electrical conditions favorable for TGF production. Finally, an overview of the experimental and field work carried out during this thesis is summarized. Ali the specialized instruments for lightning and thunderstorm measurements installed in the Colombia are detailed as well. The organization of this thesis is as follows: Chapter 1 contains the introduction addressing the state of the art of the main topic. Chapter 2 describes all the fieldwork undertaken during this thesis. Chapter 3 includes the content of the papers used for this thesis, and summarizes the main results and the conclusions of them. Chapter 4 shows the developed lightning leader model and the main results of the TGF simulations. Finally, chapter 5 presents the overall conclusions and forthcoming work.Este trabajo de investigación presenta la caracterización de estructuras eléctricas y líderes de rayos en tormentas y su relación con inicios de rayos gamma terrestres (TGFs). La investigación aporta información detallada de distribuciones de carga eléctrica, sus límites espaciales, desarrollo vertical, evolución durante su ciclo de vida e identificación de centros carga y distribuciones de carga complejas. Adicionalmente, mediante el análisis morfológico de líderes de rayos, se ha desarrollado una caracterización de alturas de inicio, trayectorias, direcciones de propagación al igual que identificación de polaridades y análisis de variabilidad temporal y espacial. Toda la caracterización mencionada fue derivada de mediciones del sistema de alta precisión de detección de tormentas eléctricas Lightning Mapping Array, el cual por primera vez se instaló en regiones tropicales durante el desarrollo de esta investigación. A partir de los resultados experimentales, caracterización de líderes y de estructuras de carga, se elaboró un modelo simplificado de líderes de rayos que aproxime las condiciones de potenciales y campos eléctricos durante propagación de descargas. Como resultado del modelo fue posible obtener distribuciones de potenciales debido a estructuras eléctricas y bajo la interacción de líderes. Adicionalmente, mediante la integración de los resultados del modelo de líder y el programa de simulación de interacción de partículas LEPTRACK , se muestran algunas condiciones eléctricas favorables que puedan dar inicio a rayos gammas terrestres (TGFs) debido a procesos de líderes de rayos y estructuras eléctricas próximas a las reportadas . Finalmente, en el documento se realizó una recopilación de todo el trabajo experimental desarrollado que permitió la puesta en marcha de toda una infraestructura altamente especializada para la investigación de tormentas eléctricas en regiones tropicales caso Colombia

Investigación de las estructuras eléctricas y líderes de rayos en tormentas : aportaciones a las condiciones de inicio de rayos gamma terrestres

Tesi per compendi de publicacions.This thesis presents a characterization of the charge structures of thunderstorms and lightning leader development, and their relationship with the emissions of terrestrial gamma ray flashes (TGFs). The results include a detailed view of thundercloud charge distributions, their altitude range and life cycle evolution. The altitude of charge centers and the identification of complex charge structures have also been included. Additionally, the developments of the lightning leaders, their altitudes of initiation, polarities, and spatial and temporal characteristics across different seasons are studied by analyzing the lightning leader signature from a Lightning Mapping Array (LMA), which was installed also for the first time in the tropics during this work. According to the characterization of charge structures, a lightning leader model is developed. The main goal of the model is to analyze the potential and the electric field stress expected during lightning discharge simulations. In addition, simulations about TGF emissions obtained from particle interactions have been included. In this case, the LEPTRACK program is used along with the main results of the leader model in order to analyze the electrical conditions favorable for TGF production. Finally, an overview of the experimental and field work carried out during this thesis is summarized. Ali the specialized instruments for lightning and thunderstorm measurements installed in the Colombia are detailed as well. The organization of this thesis is as follows: Chapter 1 contains the introduction addressing the state of the art of the main topic. Chapter 2 describes all the fieldwork undertaken during this thesis. Chapter 3 includes the content of the papers used for this thesis, and summarizes the main results and the conclusions of them. Chapter 4 shows the developed lightning leader model and the main results of the TGF simulations. Finally, chapter 5 presents the overall conclusions and forthcoming work.Este trabajo de investigación presenta la caracterización de estructuras eléctricas y líderes de rayos en tormentas y su relación con inicios de rayos gamma terrestres (TGFs). La investigación aporta información detallada de distribuciones de carga eléctrica, sus límites espaciales, desarrollo vertical, evolución durante su ciclo de vida e identificación de centros carga y distribuciones de carga complejas. Adicionalmente, mediante el análisis morfológico de líderes de rayos, se ha desarrollado una caracterización de alturas de inicio, trayectorias, direcciones de propagación al igual que identificación de polaridades y análisis de variabilidad temporal y espacial. Toda la caracterización mencionada fue derivada de mediciones del sistema de alta precisión de detección de tormentas eléctricas Lightning Mapping Array, el cual por primera vez se instaló en regiones tropicales durante el desarrollo de esta investigación. A partir de los resultados experimentales, caracterización de líderes y de estructuras de carga, se elaboró un modelo simplificado de líderes de rayos que aproxime las condiciones de potenciales y campos eléctricos durante propagación de descargas. Como resultado del modelo fue posible obtener distribuciones de potenciales debido a estructuras eléctricas y bajo la interacción de líderes. Adicionalmente, mediante la integración de los resultados del modelo de líder y el programa de simulación de interacción de partículas LEPTRACK , se muestran algunas condiciones eléctricas favorables que puedan dar inicio a rayos gammas terrestres (TGFs) debido a procesos de líderes de rayos y estructuras eléctricas próximas a las reportadas . Finalmente, en el documento se realizó una recopilación de todo el trabajo experimental desarrollado que permitió la puesta en marcha de toda una infraestructura altamente especializada para la investigación de tormentas eléctricas en regiones tropicales caso Colombia.Postprint (published version

Evolution of gigantic jets at high temporal and spatial resolution

Gigantic Jets (GJ) are lightning discharges between the cloud and the lower ionosphere, which manifest as leaders at low altitude and transition to streamers as they rise in altitude. The evolution has never been imaged before at rates faster than 1/60th second. We ran a campaign in northern Colombia with an intensified high-speed camera at 900 images per second to study the development. The image sequence reveals a weakly luminous stepwise upward propagation from the cloud top to 40 km altitude, after which continuous and much brighter branches grow to the ionosphere in 2 ms. We show the stepping to be consistent with pilot system propagation in streamers.Postprint (author's final draft

Automated analysis and statistics of lightning leader speed, local flash rates and electric charge structure in thunderstorms

We introduce new methods for the analysis of complex three-dimensional lightning data produced by Lightning Mapping Arrays and illustrate them by cases of a mid-latitude severe weather producing thunderstorm and a tropical thunderstorm in Colombia. The method is based on the characteristics of bidrectional leader development as observed in LMA data (van der Velde and Montanyà, 2013), where mapped positive leaders were found to propagate at characteristic speeds around 2 · 10^4 m s-1, while negative leaders typically propagate at speeds around 10^5 m s-1. We fit slopes (t-x, t-y, t-z) to approximate leader speed, which can be used to determine the polarity, and summarize flash rate and polarity characteristics in a 3D grid over time. The summarized data can be used to follow charge structure evolution over time, as well as climatological studies comparing lightning parameters with the meteorological environment of storms.Postprint (author's final draft

Fair weather induced charges and currents on tall wind turbines and experiments with kites

Earth’s atmospheric potential rapidly increases up to few tens of kilovolts below 200 m altitude. This potential drop will induce charge to tall objects at ground by virtue of electrostatic induction. In this work we investigate the induced electric charges in fair weather to a 1.5 MW and 5 MW wind turbines. The effect of rotation is included and the current calculated result in currents of few micro-amps. The production of point discharge and corona is investigated and some experiments are conducted by means of instrumented kites.Preprin

Meteorological factors in the production of gigantic jets by tropical thunderstorms in Colombia

Gigantic jets are electric discharges that on rare occasions can be seen at night shooting out of the top of tropical thunderclouds, reaching the ionosphere (90 km). Using sensitive camera systems and detection software, we recorded 70 events over northern Colombia and adjacent seas, most of them captured between 2016 and 2022. This is the first study to compare the meteorological background conditions for thunderstorms that produced gigantic jets in 48 nights against 83 reference cases with monitored thunderstorms that did not produce jets, using vertical profiles from ERA5 reanalysis near the event location. From the vertical profiles, various meteorological parameters are calculated, grouped by metrics of the low level convective parcel, instability, humidity, warm cloud and mixed phase parameters, and vertical wind shear, not limited to default levels. We report statistically significant differences and effect sizes (Cohen's d) for gigantic jet producing environments compared to null environments. Gigantic jets are produced in conditions with reduced low level temperatures in combination with warmer mid levels. This causes a lower cloud base and higher -10 °C isotherm altitude, thus a greater warm cloud depth, as well as reduced updraft and downdraft buoyancy. Over northern Colombia the non-GJ producing storms tend to grow in an environment that supports more vigorous, multicellular convection by enhanced low-level storm-relative winds and stronger downdrafts. Over western Colombia, the non-GJ cases tend to have a lower equilibrium level while having favorable warm cloud parameters. No evidence is found for hypotheses that upper level vertical wind shear enables gigantic jet production, nor are overshooting tops larger. The findings can be used for forecasting gigantic jets and their climatologically optimal regions on Earth. We speculate that the environmental conditions shift the droplet size distribution towards larger drops at the cost of cloud droplets, with enhanced droplet shattering ice multiplication processes as they freeze. Depending on convective evolution, low rime accretion rates could briefly expand the negative charge region downward by inverse polarity charging while the upper positive charge concentration may weaken at the same time, which could lead to a temporary negatively imbalanced electric potential distribution in the cloud needed for gigantic jet emission.Peer ReviewedPostprint (published version

Natural observatories for lightning research in Colombia

This paper presents a selected, not exhaustive, description of lightning research in Colombia over time, based on natural observatories for experimentation and measurement; and introduces the DABEIBA Lightning Research Center as a new institutional cooperation to concentrate several instruments such as Lightning Mapping Array - LMA, high speed cameras, high energy detectors, by different scientific parties in a single area for tropical lightning research. © 2018 IEEE.Peer ReviewedPostprint (published version

Gigantic jet discharges evolve stepwise through the middle atmosphere

In 2002 it was discovered that a lightning discharge can rise out of the top of tropical thunderstorms and branch out spectacularly to the base of the ionosphere at 90¿km altitude. Several dozens of such gigantic jets have been recorded or photographed since, but eluded capture by high-speed video cameras. Here we report on 4 gigantic jets recorded in Colombia at a temporal resolution of 200 µs to 1¿ms. During the rising stage, one or more luminous steps are revealed at 32-40¿km, before a continuous final jump of negative streamers to the ionosphere, starting in a bidirectional (bipolar) fashion. The subsequent trailing jet extends upward from the jump onset, with a current density well below that of lightning leaders. Magnetic field signals tracking the charge transfer and optical Geostationary Lightning Mapper data are now matched unambiguously to the precisely timed final jump process in a gigantic jet.Peer ReviewedPostprint (published version

Thunderstorm characteristics favouring downward and upward lightning to wind turbines

Meteorological conditions and thunderstorm characteristics related to lightning threats to wind turbines are discussed in this paper. Due to the rotating blades, wind turbines may be regarded peculiar tall objects, more susceptible to lightning strikes than other tall man-made structures. In the present study, Lightning Mapping Array and weather radar observations allowed to draw a clear picture of the thunderstorm characteristics leading to lightning strokes to wind turbines, in a coastal area of the Mediterranean basin. Results showed that lightning threats to wind turbines tend to occur during transitional periods (spring and autumn), although the main thunderstorm activity concentrates in the warm summer months. Thunderstorms with downward strokes to wind turbines presented particular features, like a limited vertical development and a dominant lower positive charge layer. Downward cloud-to-ground strokes hitting wind turbines were mainly of negative polarity and with peak currents above the average. On the other hand, conditions for self-initiated upwards from wind turbines resemble those reported in Japan and the U.S winter thunderstorms, with low-cloud based large electrified stratiform regions. These particular conditions, leading to lightning threats to wind turbines, should be properly included in lightning protection standards.Peer ReviewedPostprint (author's final draft

High altitude leaders mapped by the Colombia lightning mapping array

On April 2015 a Lightning Mapping Array network (COL-LMA) was installed at the north of Colombia. This network provides 3D mapping of the development of lightning leaders. For the first time such network has been setup in the tropics. That allows us to investigate the high altitude development of lightning leaders. Here we present the results of the first measurements to confirm that negative leaders at altitudes of 15 km are common in the observed thunderstorms.Postprint (published version