Publications [#283207] of Steven A. Cummer

Papers Published

1. Kelley, MC; Baker, SD; Holzworth, RH; Argo, P; Cummer, SA, LF and MF observations of the lightning electromagnetic pulse at ionospheric altitudes, Geophysical Research Letters, vol. 24 no. 9 (January, 1997), pp. 1111-1114, American Geophysical Union (AGU), ISSN 0094-8276 [97GL00991], [doi]
   (last updated on 2023/06/01)

   Abstract:
   For the first time the full ionospheric signature of the lightning electromagnetic pulse (EMP) was measured up to a frequency of 2 MHz. At altitudes below 225 km, the upward-going whistler wave is found to have a nose-whistler wave shape with the fastest propagating frequency (nose frequency) near 80 kHz. The bulk of the EMP energy is at the nose frequency, and there is a sharp upper limit near 175 kHz where the group delay is very long. We believe the group delay is due to a propagation resonance for the whistler mode (slightly non-longitudinal propagation) associated with the low plasma frequencies in the F-layer valley. MF emissions were seen below the F peak, but not above. These results verify earlier speculation that the leading intense edge of the lightning EMP was carried by 50-125 kHz waves. In addition, we present tantalizing evidence for detection of a pulse pair prior to the stroke that is similar to transionospheric pulse pairs (TIPPs) detected in satellite data. Copyright 1997 by the American Geophysical Union.

   Keywords:
   Lightning;Resonance;Plasma oscillations;F region;