A detailed 3D study of a massive electrical discharge that rose 50 miles into space above an Oklahoma thunderstorm has provided new information. The Oklahoma discharge carried 100 times the electrical charge of a typical lightning bolt.
300 coulombs of electrical charge were moved from the storm to the ionosphere. There are less than five coulombs between the cloud and ground. The leaders that are very hot are included in the upward discharge.
Levi Boggs is a research scientist at the Georgia Tech Research Institute and the paper'sCorresponding Author. The sources above the cloud top had not been seen before with this level of detail. We were able to locate the hot leader portion of the discharge using satellite and radar data.
Boggs was part of a multi-organization research team that included the Universities Space Research Association, Texas Tech University, the University of New Hampshire, and the University of Oklahoma. The research was reported in August.
Steve Cummer is an electrical and computer engineering professor at Duke University. He operates a research site that has sensors arrayed in an empty field waiting to pick up storms.
Researchers had suspected that the strongest electric current flows behind the streamers that are at the very tip of the lightning and that the VHF radio is emitted by them.
The study found that the 3D locations for the lightning's optical emissions were above the clouds.
The gigantic jet was detected by several systems, including the lightning mapping array and twogeostationary optical lightning instruments, which gave us a lot more information on gigantic jets. This is the first time that a gigantic jet has been three-dimensionally mapped above the clouds.
Over the past two decades, gigantic jets have been observed and studied, but because there is no specific system to look for them, detections have been rare. Boggs was told about the Oklahoma event by a colleague who told him about a huge jet that was photographed by a citizen-scientist in May of last year.
The event took place in a location with a nearby lightning mapping system, within range of two Next Generation Weather Radar (NEXRAD) locations and accessible to instruments on satellites. Boggs worked with colleagues to get the data together for analysis.
Boggs said that the data showed that the cold streamers begin their propagation above the cloud top. They make a direct electrical connection between the cloud top and the lower ionosphere at an altitude of 50 to 60 miles.
It takes about a second for that connection to transfer thousands of amperes. Negative charge was transferred from the cloud to the ionosphere.
The data shows that as the discharge ascended from the cloud top, VHF radio sources were detected at altitudes of 22 to 45 kilometers (13 to 28 miles), while optical emissions from the lightning leaders remained near the cloud top at an altitude of 15 to 20 kilometers (9 to 12 miles). The simultaneous 3D radio and optical data shows that lightning networks can detect emissions from streamers rather than the leader channel, which has broad implications to lightning physics beyond that of giant jets.
The jets charge into space. Something may be blocking the flow of charge downward. The Oklahoma event's records show little lightning activity before the giant jet was fired.
There is usually a suppression of cloud-to-ground discharges. The storm top has a build up of negative charge and we think that it weakens the uppermost charge layer which is usually positive. In the absence of lightning discharges, the giant jet may relieve the build up of negative charge in the cloud.
There are a lot of unanswered questions about gigantic jets. Observations of them are rare and occur by chance, from pilots or aircraft passengers to ground observers.
There are estimates for the number of jets per year. They have been reported more often in the tropics. The Oklahoma jet was not part of a tropical storm system.
Boggs said that giant jets could have an impact on the operation of satellites. signal degradation and performance issues may become more significant as more space vehicles are launched. Over-the-horizon radars that bounce radio waves off the ionosphere could be affected by the huge jets.
The Severe Storms Research Center was established at GTRI to develop improved technologies for warning of severe storms, like tornadoes, that are common in Georgia. The work on giant jets is part of the effort.
More information: Levi D. Boggs et al, Upward propagation of gigantic jets revealed by 3D radio and optical mapping, Science Advances (2022). DOI: 10.1126/sciadv.abl8731 Journal information: Science Advances
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