An explanation of trans-ionospheric pulse pairs
  Trans-ionospheric pulse pairs are the most powerful natural radio signals on the Earth and associated with lightning. They have been discovered for two decades by satellites, but their origin still remains elusive. Here we attribute these radio signals to relativistic electrons produced by cloud-to-ground lightning. When these electrons strike the ground, radio bursts are emitted towards space in a narrow cone. This model naturally explains the interval, duration, polarization, coherence and bimodal feature of the pulse pairs. Based on electron parameters inferred from x-ray observation of lightning, the calculated signal intensity agrees with the measurement of satellites. Our results are useful to develop global warning system of storms and hurricane based on GPS satellites. 
H.-C. Wu
physics.plasm-ph physics.ao-ph physics.geo-ph physics.space-ph