Accession Number : ADP006321

Title :   VLF/LF Remote Sensing of Transient and Localized Disturbances of the Lower Ionosphere Associated with Lightning Discharges,

Corporate Author : STANFORD UNIV CA SPACE TELECOMMUNICATIONS AND RADIOSCIENCE LAB

Personal Author(s) : Inan, Umran S.

Report Date : 03 MAY 1990

Pagination or Media Count : 10

Abstract : High resolution measurements of subionospheric VLF/LF signals are now established as a powerful remote sensing tool for investigation of transient and localized ionospheric disturbances associated with atmospheric lightning discharges. Events usually consist of sudden (<2 s) changes in amplitude and/or phase followed by relatively slow (10-100 s) recovery to background levels. This paper discusses recent results from a new series of observations conducted at Arecibo, Puerto Rico and at Huntsville, Alabama. The subionospheric VLF paths from two different transmitters to these two sites are nearly collinear, allowing for identification of the location of the disturbed ionospheric regions. Events observed on some very short paths indicate that selective excitation of waveguide modes can be used to extract information on the energy spectra of precipitating particles. In one case, on 23 February 1990, an extremely high rate of event activity (>60 events/hr) was observed at Huntsville on the 48.5 kHz signal from Silver Creek, Nebraska, with amplitude changes of as much as 15 dB in individual events.

Descriptors :   *IONOSPHERIC PROPAGATION, *RADIO SIGNALS, *LIGHTNING, NOISE(RADIO), WHISTLERS, VERY LOW FREQUENCY, LOW FREQUENCY, RADAR REFLECTIONS, IONOSPHERIC DISTURBANCES, REMOTE DETECTORS.

Subject Categories : Radiofrequency Wave Propagation
      Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE