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

Abstract

[1] 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.Citation: Jacobson, A. R., X.-M. Shao, and R. H. Holzworth (2011), Satellite triangulation of thunderstorms, from fading radio fields synchronously recorded on two orthogonal antennas, Radio Sci., 46, RS6012,

A Retrospective of Findings From the FORTE Satellite Mission

“…Several techniques have been explored (Jacobson & Shao, ; ; Shao & Jacobson, ; ) to exploit things like the projection of the polarization ellipse onto the earth's surface or the geomagnetically induced mode‐splitting of the signal. The different methods and their strengths and weaknesses are summarized in Jacobson et al ().…”

Lightning locating systems: Insights on characteristics and validation techniques

“…The two most common techniques used for lightning geolocation in ground‐based LLSs are time‐of‐arrival (TOA) and direction finding (DF) [e.g., Cummins et al ., ; Cummins and Murphy , ; Rakov , ]. Low‐Earth orbiting, satellite‐based LLSs use either optical imaging [e.g., Christian et al ., ] or a VHF direction‐finding technique [e.g., Jacobson et al ., ; Morimoto et al ., , ] to geolocate lightning.…”

“…Jacobson et al . [] used a noninterferometric VHF direction‐finding technique to geolocate thunderstorms approximately with data from two orthogonal VHF log‐periodic antennas on the Fast On‐orbit Rapid Recording of Transient Events (FORTE) satellite. This technique does not require combination with optical imaging to perform geolocation but is subject to 180° ambiguity (hence, two possible geolocations per detected pulse).…”

“…As discussed in section 3, VHF direction finding techniques have been used in low‐Earth orbiting satellite‐based LLSs. In general, such LLSs geolocate lightning at the storm [ Jacobson et al ., ] or cloud level [ Morimoto et al ., ]. Data collected over time by such LLSs can be used in climatological studies, but they cannot provide continuous monitoring of individual thunderstorms.…”

“…Low‐Earth orbiting satellite‐based LLSs that use a focal plane array for optical measurements in the near infrared [e.g., Christian et al ., , ] have provided lightning data over large fields of view for more than two decades. Additionally, VHF antenna systems on board low‐Earth orbiting satellites [e.g., Jacobson et al ., ; Morimoto et al ., ] can be used to detect lightning over large regions. Data from on‐board sensors are processed locally to filter out noise and geolocate lightning events.…”