A terrestrial gamma ray flash observed from an aircraft

Smith, David M.; Dwyer, J. R.; Hazelton, B. J.; Grefenstette, Brian W.; Martinez-McKinney, G. F.; Zhang, Z. Y.; Lowell, A.; Kelley, N. A.; Splitt, M. E.; Lazarus, S. M.; Ulrich, W.; Schaal, M.; Saleh, Z.; Cramer, E. S.; Rassoul, H. K.; Cummer, Steven A.; Lu, Gaopeng; Shao, Xuan‐Min; Ho, Cheng; Hamlin, T.; Blakeslee, Richard J.; Heckman, S.

doi:10.1029/2011jd016252

Cited by 64 publications

(54 citation statements)

References 30 publications

(54 reference statements)

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“…One of these pulses was associated with a fast discharging process detected by NLDN and classified correctly in this case as a +12 kA intracloud discharge (indicated by a diamond in Figure 7a). Similar magnetic pulses with larger amplitude can be produced by initial upward negative leaders in IC lightning associated with submillisecond bursts of energetic radiation (i.e., hard X‐rays and gamma rays) observed by spaceborne and aircraft‐borne detectors [ Lu et al , 2010, 2011a; Smith et al , 2011]. The upward negative leader turned horizontal and propagated for about 70 ms; the rest of this flash was dominated by K processes in the midlevel negative cloud region between 4 and 8 km (msl).…”

Section: Impulse Charge Transfer With Different Lightning Morphologymentioning

confidence: 99%

Lightning morphology and impulse charge moment change of high peak current negative strokes

Cummer

Blakeslee

et al. 2012

J. Geophys. Res.

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[1] We have analyzed very high frequency lightning mapping observations and remote magnetic field measurements to investigate connections between lightning morphology and impulse charge moment change (iCMC) of negative cloud-to-ground (CG) strokes with high estimated peak currents. Four lightning morphologies are identified for a total of 2126 strokes within optimum detection range of the North Alabama Lightning Mapping Array, and statistical iCMC distributions are given for each of these types. Almost all (>90%) of the largest impulse charge moments (greater than À200 C km in this data set) are not produced by strokes in ordinary negative CG flashes. Instead, negative strokes with the largest iCMCs are almost exclusively associated with two unusual flash types that both initially develop as positive (normal) intracloud lightning. In the first type the negative stroke with high iCMCs results from a negative leader that descends from the midlevel negative charge region after the upper level negative leader ceases propagating. In the second type, the upper level negative leader of the intracloud lightning progresses toward ground as a so-called bolt from the blue to generate the negative stroke. Measurements of strokes associated with four negative polarity sprites suggest that all four were most likely produced in the first unusual lightning type. Our results highlight that estimated peak current and impulse charge transfer are not always well correlated and that the in-cloud lightning structure strongly influences charge transfer on short time scales in negative CG strokes.

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Section: Impulse Charge Transfer With Different Lightning Morphologymentioning

confidence: 99%

Lightning morphology and impulse charge moment change of high peak current negative strokes

Cummer

Blakeslee

et al. 2012

J. Geophys. Res.

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“…Astrorivelatore Gamma a Immagini Leggero (AGILE) has observed 130 events satisfying stringent TGF selection criteria during the period June 2008 to January 2010 [ Tavani et al , 2011]. In addition one TGF has been observed from an airplane by the Airborne Detector for Energetic Lightning Emissions (ADELE) [ Smith et al , 2011]. The limited number of events is partially due to the high trigger threshold imposed on the data in order to eliminate spurious events.…”

Section: Introductionmentioning

confidence: 99%

A new method reveals more TGFs in the RHESSI data

Gjesteland¹,

Østgaard²,

Collier³

et al. 2012

Geophysical Research Letters

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This letter presents a new search algorithm for identifying Terrestrial Gamma ray Flashes (TGFs) in the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) data. The algorithm has been applied to data from the period 2004–2006 and we have found more than twice as many TGFs as previously reported. The new TGFs follow the same geographical and seasonal variations as the previously reported TGFs. The match percentage between the new TGFs and World Wide Lightning Location Network (WWLLN) data is comparable to the RHESSI catalog TGFs. Our results shows that previous searches only identified the most intense events, and that there might be a large population of faint TGFs.

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“…In addition to a ground level flash observed in 2003 [ Dwyer et al , 2004a] (see Section 1.2), before this work, only one other TGF has been observed from within our atmosphere. That event was measured by the ADELE instrument onboard a NCAR/NSF G‐V aircraft at an altitude of 14.1 km, approximately 10 km away from the TGF source within a thundercloud near the Florida/Georgia border [ Smith et al , 2011]. Even though the event was relatively close to the aircraft, 10 km compared to 600 km for spacecraft, at the 14.1 km altitude there was enough air between the TGF and the aircraft to attenuate the gamma‐rays so that the number of photons measured was about the same as from space.…”

Section: Introductionmentioning

confidence: 99%

Observation of a gamma‐ray flash at ground level in association with a cloud‐to‐ground lightning return stroke

Dwyer¹,

Schaal²,

Cramer³

et al. 2012

J. Geophys. Res.

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Terrestrial gamma‐ray flashes (TGFs) are bright, sub‐millisecond bursts of gamma‐rays, originating within the Earth's atmosphere. Most TGFs have been detected by spacecraft in low‐Earth orbit. Only two TGFs have previously been observed from within our atmosphere: one at ground level and one from an aircraft at 14.1 km. We report on a new TGF‐like gamma‐ray flash observed at ground level, detected by the 19‐station Thunderstorm Energetic Radiation Array (TERA) at the University of Florida/Florida Tech International Center for Lightning Research and Testing (ICLRT). The gamma‐ray flash, which had a duration of 52.7 μs, occurred on June 30, 2009 during a natural negative cloud‐to‐ground lightning return stroke, 191 μs after the start of the stroke. This event is the first definitive association of a gamma‐ray flash with natural CG lightning and is among the most direct links to a specific lightning process so far. For this event, 19 gamma‐rays were recorded, with the highest energy exceeding 20 MeV. The high‐energy radiation exhibited very different behavior from the typical x‐ray emission from lightning. Specifically, the gamma‐ray flash had a much harder energy spectrum, consistent with relativistic runaway electron avalanche (RREA) multiplication; it did not arrive in sub‐microsecond bursts, typical of leader emission from lightning, and it occurred well after the start of the return stroke, which has not been previously observed for the x‐ray emission from lightning. Nevertheless, we present evidence that the source region for the gamma ray flash was the same as that for the preceding leader x‐ray bursts.

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A terrestrial gamma ray flash observed from an aircraft

Cited by 64 publications

References 30 publications

Lightning morphology and impulse charge moment change of high peak current negative strokes

Lightning morphology and impulse charge moment change of high peak current negative strokes

A new method reveals more TGFs in the RHESSI data

Observation of a gamma‐ray flash at ground level in association with a cloud‐to‐ground lightning return stroke

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