STATISTICS ON ARTIFICIALLY TRIGGERED LIGHTNING

The Faculte Polytechnique of Mons has participated in the last three programs of artificially triggered lightning in Saint-Privat d'Allier, France (1986 1990, and 1991). Measurements of the vertical part of the electric field E and electric field derivative (dE/dt) only 50 m from the discharge were made in 1990 and 1991. Our data, combined with those of the Centre National d'Etudes des Telecommunications, the Centre d'Etudes Nucleaires de Grenoble, and the Ecole Centrale de Lyon, lead us to a statistical study bf the electrical parameters obtained from artificially triggered discharges in Saint-Privat d'Allier. We define the statistical distributions of these electrical parameter populations and establish some relations between them, We compare artificially triggered lightning with natural lightning and conclude that the triggered lightning strokes are very similar to the subsequent strokes of natural lightning. We also compare the Saint-Privat d'Allier triggered lightning with the Kennedy Space Center (Florida) triggered lightning. The Kennedy Space Center is at sea level and has a high ground conductivity. while Saint-Privat d'Allier is a mountainous country with strong resistivity. Main results are, for the current, 50 % of triggered strokes are higher than 12.1 kA in Florida (statistics of 305 strokes) and 9.8 kA in Saint-Privat d'Allier (54 strokes); for dI/dt, 50 % Of triggered strokes have a dI/dt higher than 91.4 kA/mu s in Florida (134 strokes) and 36.8 kA/mu s in Saint-Privat d'Allier (47 strokes); 5 % of the strokes have a dI/dt higher than 297.7 kA/mu s in Florida, The best relation (best correlation coefficient) between (dI/dt (kA/mu s) and I (kA) is dI/dt = 2.6 I-1.34 in Florida (134 strokes) and dI/dt = 2.0 I-1.28 in Saint-Privat d'Allier (47 strokes).