Lightning sferics and stroke-delayed pulses measured in the stratosphere: Implications for mesospheric currents

During the Brazil Sprite Balloon Campaign 2002 - 03, the vector ELF to VLF ( 25 Hz - 8 kHz) electric and magnetic fields driven by cloud-to-ground (CG) lightning strokes at horizontal distances of 75 - 600 km were measured at altitudes of 30 - 35 km. Electric field changes were measured for each of the 2467 CG strokes detected by the Brazilian Integrated Lightning Network. ELF pulses that occur 4 - 12 ms after the retarded time of the lightning sferic, which have been previously attributed to sprites, were found for 1.4% of 934 strokes examined. Thus, lightning-driven electric and magnetic field changes were common and stroke-delayed ELF pulses were rare, which disagrees with results from the Sprites99 Balloon Campaign.