Research on multiple atmospheric Earth discharge, their development and mechanism, and impact on the hazard to people and objects
The main goal of the project was to determine the parameters of multiple ground lightning discharges and to identify the structure of the electric charge in the areas where these discharges were initiated in a storm cloud. This task required the development, construction, and installation of a new, local lightning discharge recording system performed for the Local Lightning Detection Network (LLDN) - enabling the simultaneous measurement of changes in the electric field intensity generated by ground lightning discharges in the low-frequency (LF) band (from 20 Hz to 100 kHz) by six stations/antenna systems located in the Warsaw area. Each station consists of an antenna system and a digital recording device. The antenna system was designed and manufactured at the Warsaw University of Technology, and the recording devices were manufactured at the Space Research Centre of the Polish Academy of Sciences. It was assumed that the LLDN system would enable three-dimensional (3D) localization of the source of electric charge and determination of the value of this charge (Q), discharged during individual phases of the main earth discharge, subsequent discharges, and during the flow of the long-term component of the discharge current. The spatial location and value of the electric charge were calculated based on an electrostatic model of a point source of charge placed above a conductive plane. For this purpose, a calculation methodology was used based on a matrix system of algebraic equations and statistical assessment of their accuracy using the chi square test. The algorithm and software necessary to perform numerical calculations to determine the value and location of this charge were developed at the Institute of Geophysics of the Polish Academy of Sciences. The results of two-dimensional (2D) localization of individual multiple lightning discharges were compared with data obtained from the nationwide lightning discharge recording system PERUN (SAFIR), operated by the Institute of Meteorology and Water Management. These data enabled verification of the quality of information about lightning discharges obtained in Poland from the PERUN (SAFIR) system in Warsaw and the surrounding area. The lightning discharges were recorded continuously for three months during the 2009 thunderstorm season. An analysis was conducted of the time histories recorded simultaneously by all measurement antennas for the same lightning discharges, which were identified based on an analysis of their recording times using the GPS systems equipped at each station. Several series of measurements of the electric field accompanying ground discharges were supplemented with photographic recordings using high-speed MIRO digital cameras (capable of recording at speeds of up to tens of thousands of frames per second), purchased for the implementation of this project. Statistical data on the number and parameters of individual ground discharges in each year of project implementation was obtained from the PERUN (SAFIR) system, as well as data on the surface density of ground discharges in Poland and the Warsaw region, i.e., the area covered by the LLDN registration. Such data are necessary to assess the degree of lightning hazard to buildings and their equipment, as well as to assess the risk to people both inside the buildings and in open spaces. Identification of potential threats related to ground lightning discharges, analysis of the associated risk of lightning damage/loss.
Additional Info
| Field | Value |
|---|---|
| Additional | This research project was realized in connection with the COST P18 Action "Physics of Lightning Flash and Its Effects" in 2007-2009 |
| Call | Specjalny Projekt Badawczy |
| Project Coordinator | Dr. Eng. Marek Łoboda, Department of Electrical Engineering, Warsaw Technical University |
| Project Financing Institution | State Committee for Scientific Research (Komitet Badań Naukowych) |
| Project ID | 145/1/COS/2006/1 |
| Time | 22/02/2007 - 21/11/2009 |