THE INTERACTION WITH THE LOWER IONOSPHERE OF ELECTROMAGNETIC PULSES FROM LIGHTNING - EXCITATION OF OPTICAL-EMISSIONS

A self consistent and fully kinetic simulation of the interaction of lightning radiated electromagnetic (EM) pulses with the nighttime lower ionosphere indicates that optical emissions observable with conventional instruments would be excited. For example, emissions of the 1 st and 2nd positive bands of N2 occur at rates reaching 7 x 10(7) and 10(7) cm-3 s-1 respectively at approximately 92 km altitude for a lightning discharge with an electric field E100 = 20 V/m (normalized to a 100 km distance). The maximum height integrated intensities of these emissions are 4 x 10(7) and 6 x 10(6) R respectively, lasting for approximately 50 mus.