A lightning bolt of record. It reached a length of 130 km and a duration of 6.2 seconds. It occurred on September 15 in the Ebro delta and was recorded by the Lightning Research Group of the UPC, made up of researchers and professors from the Higher School of Industrial, Aerospace and Audiovisual Engineering of Terrassa (ESEIAAT).
Few know that there are lightning strikes that can have extensions of more than 100 km and that can form an electrical chain reaction lasting more than 6 seconds. This is the case of the longest lightning bolt known in Catalonia in the last ten years, recorded by the Lightning Research Group of the Polytechnic University of Catalonia – BarcelonaTech (UPC), the international reference research group formed by researchers and professors from ESEIAAT .
The Lightning Research Group has recently renewed the technological equipment with which they have been working since 2011, through financing from the Next Generation funds of the European Union and the Ministry of Science and Innovation. The new equipment allows them to expand the coverage of action, to better study and record the rays with greater precision. And global warming is affecting the activity of very strong storms in certain places on the planet, including Catalonia. In this context, the group has positioned itself at the forefront of international research in this area.
More than ten years ago, this group of researchers from the Department of Electrical Engineering at the UPC and professors from ESEIAAT installed the first three-dimensional lightning mapping network in Europe in the Ebro Delta, which supported the International Space Station. It has been forming the eLMA (Lightning Mapping Array) network, made up of 15 stations spread throughout the valley and the Ebro Delta, where each station detects the radio emissions produced by lightning that develops inside the storm cloud.
By combining signals received by the stations, researchers obtain three-dimensional locations. In addition, with a high-speed camera with an image intensifier, they record videos of up to one million images per second, so they can study, in great detail, the entire process of generating and completing the rays.
Through the observation stations of the eLMA network, the Lightning Research Group also produces lightning density maps thanks to which, for example, the intensity of storms can be measured, such as the one that devastated the Ebro Delta on last August 26 with an extraordinary hailstorm. In that case, the map showed a break from the usual pattern of altitude distribution of electrical activity that reached up to 17 km at the top of the cloud.
The maps that emerge from the records from the 15 observation stations are capable of showing, for example, lightning holes in a territory, as is the case of the supercell storm that formed in the center of Aragon during the afternoon of last July 6th. Supercell storms form as a result of the encounter of a warm current with a cold front; The temperature difference causes a wind vortex that generates a messocyclone, that is, an episode of severe weather that can last for hours.
Now, with the new equipment, valued at one million euros, the researchers have been able to participate in the ALOFT (Airborne Lightning Observatori for FEGS and TEGS) campaign, thanks to which a NASA plane has been able to fly over storms on the islands of the Caribbean, to look for high-energy emissions (gamma rays) produced by lightning. In this project, the research group provides measuring instruments located on land, on the island of San Andrés.
One of the main uses of the eLMA network is the detection of severe atmospheric events, such as hailstorms, thunderstorms and tornadoes. In fact, severe storms present unique patterns of electrification and very marked differences in lightning activity. The eLMA network will be used as a reference for the new Ligthning Imager lightning detector of the third generation of METEOSAT satellites. Likewise, a lightning measurement campaign is planned through the eLMA, in Africa, for the validation of the new meteorological satellite.
