Signatures of Remote Intense Lightning on a Quasi-static Displacement Current Sensor
Abstract
A unique standalone lightning location system developed by Biral(UK) has been used to monitor the atmospheric electric field variability at ground in Bristol (51.483 N, 2.769 W) since 2014. The sensor measures the displacement current induced on 3 co-located stainless steel conductors (100Hz sampling rate), which is proportional to the rate of change of the local electric field in the range 1-45Hz. An extensive study of recordings during fair-weather has shown clear evidence of large amplitude disturbances originated from intense remote lightning sources up to 1,000 km away from the sensor and typically characterised by peak currents values exceeding 100 kA. We present the analysis of a storm in southern Europe during the night of 6-7 June 2015, which produced about 100 transient luminous events (TLE), as observed with a video camera at Pic du Midi (42.93N, 0.14E; 2877 m). The structure of the the storm is described using the Meteosat satellite data and the lightning activity from Meteorage, which provides data enabling the identification of location, polarity, peak current value, number of strokes and timing of flashes. Applying a selection criteria to the quasi-static current recordings, making use of a covariance threshold between the primary and secondary antenna, it is possible to identify the most prominent events detected in relation to the storm. In particular, selected events are found to be coincident in a one-to-one correlation to all the elves and the brightest sprites observed by the camera. We focused on these distinctive observable signatures in order to discriminate between different types of TLEs, by including additional broadband EM for further characterization of the sources. The reconstructed current moment waveforms and charge moment changes associated with large and bright sprite events were obtained from the ELF station in Hylaty (Poland). A possible complementary application for the sensor is then suggested, as a proxy for the occurrence of intense discharges, including those associated with TLEs. The method is especially profitable to monitor such events above the sea, where optical ground-based camera coverage is often poor and without the limitation of clear skies and obstructed views.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMAE21B3070P
- Keywords:
-
- 3304 Atmospheric electricity;
- ATMOSPHERIC PROCESSES;
- 3324 Lightning;
- ATMOSPHERIC PROCESSES;
- 0694 Instruments and techniques;
- ELECTROMAGNETICS