Upper atmospheric remote sensing using ELF – VLF lightning generated tweek and whistler sferics

Abstract

Tweek and whistler atmospherics (sferics) recorded at a low latitude station, Suva (18.2^oS, 178.3^oE, geomag. lat. 22.2^oS, L = 1.17) Fiji, in the South Pacific region, during September 2003–July 2004 and March–December 2006 were analyzed to probe the nighttime D-region ionosphere and plasmasphere. From the first harmonic analysis of the selected 1063 tweeks, the path integrated ionospheric reflection height was estimated mostly between 75–97 km with median and standard deviation of 83.6 and 4.1 km, respectively. The path integrated mean electron density was estimated to vary from 24.4–31.5 cm^–3 over the reflection heights. The whistler recorded on 20 September 2006, a magnetically quite day with maximum three hourly K_p value of 2_o, most likely propagated in the ducted mode to this station. The whistler spectrum was used to calculate the equatorial magnetic field and the equatorial electron density at L = 1.3 which are in agreement with low latitude whistler observations.