INTENSITY PEAKS IN LOW LATITUDE VLF EMISSIONS OBSERVED AT ARIEL SATELLITES

A detailed analysis of low latitude VLF emissions observed aboard Ariel 3/4 satellites shows that some N-zone 3.2 kHz emissions are more intense than S-zone emissions. It is shown that these emissions are of an impulsive nature having their origin in lightning discharges in the S-zone. These emissions propagate to equatorial altitudes in whistler mode, are amplified there by cyclotron instability and then, propagating in whistler mode, arrive at Ariel satellites in the N-zone. Observations of VLF events and particle precipitation at lower L-shells support our conclusion.