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 l ightning radiated electromagnetic (EM) pulses with the nighttime lower ionosphere indicates that optical emissions observable with conventio nal instruments would be excited. For example, emissions of the 1 st a nd 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 lightnin g discharge with an electric field E100 = 20 V/m (normalized to a 100 km distance). The maximum height integrated intensities of these emiss ions are 4 x 10(7) and 6 x 10(6) R respectively, lasting for approxima tely 50 mus.