Analysis of five Gigantic Jets observed near Réunion Island with video and photographic cameras

Abstract

Five gigantic jets (GJ) have been recorded by a camera on March 7th 2010, at a very closedistance above an isolated tropical storm east of Réunion Island. Three of them were produced within about 4 minutes before the storm reached its coldest cloud top temperature (-81°C), and two others occurred during the extension of the cloud. The GJs tops have been estimated between 80 and 90 km. According to ELF data recorded at Nagycenk (Hungary), all GJs are negative. The GJs are accompanied by long continuous cloud illumination and they are preceded and followed by intermittent optical flashes from the cloud. The jet duration ranged from 333 ms to 850 ms while that of the leading jets markedly varied from 33 to 167 ms and that of the trailing jets ranged from 300 to 683 ms. The trailing jet exhibits a continuous decrease of luminosity in different parts of the jet (lower channel, transition zone and for most events carrot sprite-like top) and in the cloud. The lowers channels (~20-40 km altitude) produce blue luminosity which decreases with altitude and becomes more and more diffuse with time. The transition zone (around 40-65 km) consists of red luminous beads slowly going up (~ 104 m s-1), jet channels.