Six-component electromagnetic wave measurements of sprite-associated lightning

Low frequency electromagnetic waves emitted by sprite-producing lightning are normally measured using vertical electric fields or horizontal magnetic fields. Here we report for the first time the simultaneous measurement of electromagnetic waves from sprite-producing lightning in all six electromagnetic field components (Formula presented.). A rigorous assessment of the horizontal electric field measurements with dipole antennas in two independent calibration experiments shows that a timing uncertainty of (Formula presented.) ns can be achieved, well above the current fundamental limit of the timing accuracy (Formula presented.) 1–5 ps. The coupling between the electric and magnetic fields is quantified using a transfer matrix, allowing the magnetic field to be reconstructed accurately from electric field measurements. The cross product of electric and magnetic fields is used to calculate peak energy fluxes and arrival azimuths from sprite-producing lightning. It is found that peak energy fluxes vary between (Formula presented.) 10–1,000 (Formula presented.) (Formula presented.) and that the differences between the measured and expected arrival azimuths are practically normally distributed with a mean and standard deviation of (Formula presented.). It is concluded that horizontal electric field measurements are well suited to characterize electromagnetic waves with added benefits, including the ease of deployment in harsh environments, cost-effectiveness and scalability, for example for polarisation measurements in large low frequency arrays. The significance of this study is that it can be used as a pathfinder mission to identify critical technical requirements for the array deployment during the Africa2Moon lander mission.