Effect of Lightning on Ionospheric Temperatures

ABSTRACT: It has been realized in recent years that the ionospheric temperature and ion density may be influenced by lightning. The ionospheric ion densities (O, O2 , H and He) and electron and ion temperatures were measured by the RPA payload aboard the Indian SROSS-C2 satellite. The data at low latitudes falling in the Indian subcontinent in the height range 425 – 625 km for the period 1995–1998 were chosen for this study. Thunderstorms are the main source of lightning (Gupta, 1999; Inan et al, 1991; Otsuyama, 1999). The data on thunderstorm activity for the same period was obtained from India Meteorological Department (IMD). For our analysis the measurements over Bhopal, Panji and Trivandrum were chosen for which the data on thunderstorm activity is also available. Comparison has also been made with IRI model (Bilitza, 1990). It has been found that the electron temperature was enhanced during thunderstorms activity by 1.4 to 2.3 times over the quite days. A similar enhancement has been found to be 1.2 to 1.7 times in the ion temperature. In all the events the ion density of above ions were found to be unaffected by the thunderstorms activity. It has been argued that the agencies like run-away electrons, UHF emissions from lightning and lightning sprites (Taranenko et al, 1992; Yukhimuk et al 1999; Bell et al, 1995) may cause the increase of ionospheric temperatures.