AASERT97 Student Support for Observations Relevant to Sprites and Jets
Final rept. 6 Jan 1997-31 May 2000
OKLAHOMA UNIV NORMAN
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During the Summer and Fall of 1998 five balloon-borne instruments were launched into thunderstorms to observe changes in the vertical component of electric field caused by lightning. Data from two flights have been compared with data from the National Lightning Detection Network NLDN for cloud-to ground lightning flashes that were coincident in time. The field changes observed at altitude appear to have been caused by charge movements relatively nearer the instruments than the ground-strike location of coincident flashes. LFNLF signals by which ground strikes are located by the NLDN are often accompanied by broadband VHF emissions recorded by receivers on the FORTE satellite. For the period April through September, 1998, 6131 FORTE satellite VHF data records have been assigned the median NLDN coordinates of their corresponding source storm. During the same time period, approximately 25 of the events detected by the photodiode detector PDD aboard the FORTE satellite over the continental United States and classified as lightning were associated with flashes detected by the NLDN. About 50-70 of PDD events with estimated peak optical source powers greater than 10 gigawatts but only about 10-25 of events with lesser source powers were associated with NLDN locations. It appears that PDD optical events with high estimated peak source power are more likely to be associated with cloud-to-ground flashes.