Satellite triangulation of thunderstorms, from fading radio fields synchronously recorded on two orthogonal antennas

摘要

Single-satellite observations of lightning radio emissions normally do not independently provide useful thunderstorm location. The scientific value of these radio waveform recordings is greatly enhanced by knowing at least the approximate location of the source thunderstorm. Since the Very High Frequency radio emissions from lightning are always broadband and usually incoherent, radio interferometry is an obvious approach to direction-finding the source. However, radio-interferometry requires separated, deployed antennas, and for decametric radio waves, success with interferometric direction-finding on a satellite has not yet been reported. We describe a method for approximate location of source thunderstorms, using the statistical fading of the received electric field on two orthogonal, but co-located, antennas. The method is based on previous work geolocating polarized sources, and we show that it can be adapted efficiently to unpolarized radio fields, which constitute the majority of lightning emissions. We implement the method with dual-antenna radio recordings from the FORTE satellite, and demonstrate its capabilities using a wide variety of radio data.