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During the summer of 1987, a rocket-triggered-lightning program was conducted at the NASA Kennedy Space Center, Florida. The rocket triggering was performed from two trigger platforms - one over water and the other over land. The propagation paths from the two sites were almost entirely over brackish water. This report presents waveform plots of the electric-field time derivative, the electric field, and the high-frequency spectral density at 5 MHz.

Experimental results from a two year aircraft investigation of the atmospheric electrical and meteorological properties of the unstable planetary boundary layer (PBL) are reported. The primary objectives of the research were to 1) examine the strength of the electrode effect charge source over land and sea, and 2) obtain simultaneous measurements of meteorological and charge fluxes under varying conditions of atmospheric stability to test predictions of a second order closure model of charge transport. Soundings of electric field, conductivity, temperature, condensation nuclei, dew point, and turbulence structure functions for velocity, temperature and humidity along with surface temperatures and wind speeds were obtained over the desert in southeastern New Mexico in May 1986, and over water in the Bahamas in March 1987. Our results indicate 1) strong electrode layers form over the ocean but are often inhibited over land by surface radioactivity and 2) the shape and intensity of convection current profiles are dependent on electrical relaxation and turbulence intensity as predicted by the charge transport model.

DTRT57-05-D-30103, Task 13A, FA2R/DL411, The Aerospace Corporation was tasked by the Volpe National Transportation Systems Center to provide technical support to the Federal Aviation Administration, Office of Commercial Space Transportation, in assessing the risks involved with triggered lightning during, suborbital launches and reentries of reusable launch vehicles (RLVs) from four regional spaceports, viz., Spaceport America in New Mexico, the Oklahoma Spaceport, the Mojave Air and Space Port in California, and the West Texas Spaceport. Risk of triggered, lightning was studied for four conceptual RLVs originating and/or landing at these spaceports. Five areas were addressed: (1) observed frequencies of natural cloud-to-ground lightning at four spaceports, including data from two existing lightning-mapper arrays, plus estimates of violation frequencies of the other existing lightning flight commit criteria (LFCC), (2) literature summary and new approximate analysis of the effective conducting length of the vehicle plumes, (3) review of the current LFCC to determine if the criteria are relevant to each suborbital RLV concept, including an evaluation of local geographical effects pertaining to each spaceport to determine whether additional LFCC are necessary to conduct safe launch operations there, (4) evaluation of risk based on airborne electric field measurements and cloud, temperature and lightning data, and (5) evaluation of an aircraft icing index as an indicator of high electric fields in clouds at sites that are not instrumented with weather radars and temperature sounders.