Electromagnetic signatures of the Puerto Rico blue jet and its parent thunderstorm
Abstract
On September 15, 2001, a spectacular blue jet was observed over an oceanic thunderstorm from a vantage point only 200 km distant at Arecibo Observatory, Puerto Rico (PR) [Pasko et al., Nature, 416, 152, 2002]. Unlike previous blue jets documented on video, the PR jet propagated all the way up from the top of the thunderstorm at ~16 km altitude to the base of the ionosphere at ~70 km altitude and re-illuminated several times afterwards. Broadband (<1 Hz - 250 kHz) electric field data was recorded by the New Mexico Tech sferic system at Dominguito, PR, only a few kilometers north of Arecibo Observatory, while magnetic field data was continuously recorded by Stanford University at Palmer Station, Antarctica. Several minutes prior to the jet, light-intensified video indicated that the storm had an abnormally high flash rate of roughly one per second. A preliminary analysis of the sferic data indicates that an unusually high percentage of the flashes were intraclouds. The blue jet appearance was preceded less than a second earlier by an energetic positive bipolar event which likely marked the onset of a normal-polarity intracloud (IC) flash which transported negative charge upwards. Numerous IC pulses followed the bipolar event up to and during the blue jet event. A couple of the most spectacular IC pulses after the "first stroke" of the jet to the ionosphere were coincident with dramatic re-illuminations of the jet. The polarity of these waveforms indicated that negative charge was being transported upwards, and possibly into the jet towards the ionosphere. This inferred charge motion was counter to that which establishes the fair weather field between the earth and the ionosphere.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFM.A62D..02M
- Keywords:
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- 2409 Current systems (2708);
- 2411 Electric fields (2712);
- 3304 Atmospheric electricity;
- 3324 Lightning