Coincident radio frequency and optical emissions from lightning, observed with the FORTE satellite

We present long optical and radio frequency (RF) time series of lightning e vents observed with the FORTE satellite in January 2000. Each record contai ns multiple RF and optical impulses. We use the RF signatures to identify t he general type of discharge for each impulse according, to the discriminat ion techniques described by Suszcynsky et al, (2000) and reviewed herein. W e see a large number of paired, impulsive events in the RF which allow us t o study the heights within clouds of several events, We also see that the r ate of RF/optical coincidence depends on the type of discharge: nearly 100% of VHF signals from first negative return strokes have an associated optic al signal, whereas a mere 50% of impulsive intracloud events appear to have an optical counterpart. While the RF signals from ground strokes clearly c oincide with simple optical signals in almost all cases, the intracloud lig htning often shows nearly continuous, complicated RF and optical emissions which do not cleanly correlate with one another. The RF and optical pulses do not show a well-defined relationship of intensities, for any lightning t ype. The observed delay between the RF and optical pulses we interpret as m ainly an effect of the scattering experienced by the light as it traverses the cloud. For intracloud lightning, we find no evidence of an intrinsic de lay at the source between the onset of the RF and optical signals. Impulsiv e in-cloud RF events are seen to occur on average every 0.9 ms during a fla sh.