Sprite over South Africa

Abstract

Sprites are a middle atmosphere gas discharge phenomenon powered by large positive cloud-to-ground lightning strikes which have an average peak value of ~74 kA. Sprites appear in different forms, such as carrot, jellyfish, column or disk-shaped, typically in the height range ~40-90 km. Sprites are part of the global electric circuit. Lightning strikes and sprites produce unique Very Low Frequency (VLF. and Extremely Low Frequency (ELF. radio wave signatures that can be detected remotely on the ground. South Africa has large convective thunderstorms typically in January and February of every year. Sprites were recorded for the first time in January 2016 from Sutherland using a night-vision TV camera from SANSA's Optical Space Research laboratory. Lightning strength, time and position data is obtained from the SA Weather Service and may also be tracked in real time using the World Wide Lightning Locating Network (WWLLN.. The aim of this research is to characterize the maximum altitude of sprites as a function of the lightning magnitude. Dual-camera observations, for example from Sutherland and Carnarvon in the Northern Cape, using night-vision TV cameras will be used to simultaneously record the sprites from two separated locations. The cameras' spatial pointing geometry was calibrated using stars. The algorithm for distance and height triangulation in spherical coordinates (latitude, longitude, altitude. was developed. The data from 2016 Sprites campaign was processed and we found that the average maximum altitude, and altitude of maximum brightness, of sprites is approximately 85 and 69 km, respectively. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.