| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
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| Initial Amendment Date: | April 7, 2015 |
| Latest Amendment Date: | May 13, 2019 |
| Award Number: | 1452605 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Chungu Lu
AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | April 15, 2015 |
| End Date: | March 31, 2019 (Estimated) |
| Total Intended Award Amount: | $300,000.00 |
| Total Awarded Amount to Date: | $300,000.00 |
| Funds Obligated to Date: |
FY 2016 = $116,320.00 FY 2017 = $68,379.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
202 HIMES HALL BATON ROUGE LA US 70803-0001 (225)578-2760 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
LA US 70803-4001 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Physical & Dynamic Meteorology |
| Primary Program Source: |
01001617DB NSF RESEARCH & RELATED ACTIVIT 01001718DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Satellite observations of intense millisecond flashes of gamma rays (Terrestrial Gamma Flashes - TGFs) produced at the tops of thunderstorms have shown that lightning can accelerate electrons to very high energy levels, well above 100 million electron volts (MeV). A recent experiment at Louisiana State University (LSU) has now shown that TGFs are produced by lightning near the Earth's surface, and that the gamma ray intensity at the source is extremely high. The TGF and Energetic Thunderstorm Rooftop Array (TETRA) at LSU shows the existence of ground-level TGFs associated with nearby lightning. This project is a follow-up experiment, TETRA-II, intended to measure the energy and intensity spectrum with improved statistics, extend the energy range, determine the height at which TGFs are produced, and provide for the first time correlated radiation and meteorological data. TETRA-II will be located at two sites in Puerto Rico and Jamaica, at locations where thunderstorm activity is significantly higher than at the current TETRA site in Louisiana and where satellite overflights will enable looking for TGFs simultaneously from the ground and from space.
Intellectual Merit:
Satellite observations of TGFs have shown the connection between the gamma rays and lightning. Typically, though, it is difficult to associate the gamma ray events with individual well-localized thunderstorms. The ground-level observations reported by TETRA have made it possible to associate the gamma rays with lightning within 3 miles or closer to the detectors, and have made it possible to begin to study the correlations with detailed radar images of the thunderstorms. TETRA-II will be located in a region chosen to have high lightning density and a high frequency of TGFs seen by orbiting gamma ray satellites; it will be designed to have a factor of 5 better statistics than TETRA for individual events and a higher energy range (up to 10 MeV) so that measurements can be compared to model predictions; and it will be operated in conjunction with both a local array of low frequency (LF, ~100 kHz) lightning detectors and broadband global and regional networks capable of observing intra-cloud in addition to cloud-to-ground lightning, together with nearby radar. As a result, TETRA-II is expected to provide unique and detailed new data about TGFs observed close to lightning, providing new information both about the production mechanisms of the high energy radiation and about the connection with the lightning events.
Broader Impacts:
TETRA-II will be built and operated largely by a student team. Equipment funds have been provided by the Louisiana Board of Regents, with the equipment construction to be performed by students from LSU and two nearby HBCUs (Southern University in Baton Rouge and Xavier University in New Orleans). LSU staff will do the primary design, train and supervise the students, and oversee the construction. At the same time, an array of low frequency lightning detectors will be deployed and operated by the student teams in Puerto Rico and Jamaica in order to make final determinations of the sites, explore remote operations at the two sites, gain experience with the lightning detection, and organize the Puerto Rico and Jamaica teams to be able to perform continued maintenance and operation of the detectors in the field. After a year of initial detector construction and testing by the students in Louisiana, the detector array will be deployed during the summer of 2015. The array will be operated remotely and the data analysis led from Louisiana, with contributions from the student teams in Puerto Rico and Jamaica.
Initial results are expected by the fall of 2015. A goal will be to use TETRA-II to provide research opportunities for students from LSU, Southern, Xavier, Univ. of Puerto Rico, and Univ. of the West Indies in Jamaica for at least 5-10 years. The experiment will also contribute to the development of research capability in Puerto Rico and a developing nation in the Caribbean (Jamaica). This NSF support is intended to provide operating funds for LSU and the Univ. of Puerto Rico at Bayamon. The Jamaica collaborators will request independent funding from US-AID.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The science objectives of the ground-based TETRA (TGF and Energetic Thunderstorm Rooftop Array)-II experiment are to measure the flux and energy spectrum of gamma-rays from electrons accelerated to high energies by the electric fields in terrestrial lightning, and to associate the gamma-rays with the thunderstorm characteristics. Electrical storms in the atmosphere provide the highest energy natural particle accelerators on Earth, and understanding how they accelerate particles to high energy and produce energetic radiation is of great interest. Nationally, lightning causes over $30M of damage yearly and over 100 deaths/year, more deaths than any other convective weather condition including hurricanes, tornadoes, hail, and wind. Thunderstorms can pose a serious threat to recreational, business, and utility sectors. Understanding and forecasting thunderstorms and reporting actual lightning activity can, as a broad long-term impact, lead to increased civilian awareness of this potentially dangerous phenomenon and help reduce its threat.
TETRA-II arrays are now operational and taking data on the campus of Louisiana State University (LSU) in Baton Rouge, LA; at the University of Puerto Rico (UPR) in Utuado, PR; and at the Centro Nacional de Metrología de Panamá (CENAMEP) Laboratory in Panama City, Panama. All three sites are locations where the lightning rate is high. In addition, for the Puerto Rico and Panama sites, there is satellite coverage that will potentially enable observation of thunderstorms from above and below. Terrestrial Gamma Flashes (TGFs), intense millisecond-duration bursts of X-rays and gamma rays produced by lightning, have been observed with satellite detectors since the 1990’s. Ground-based observations have been scarce, but these have the potential advantage that the observations are made within a few kilometers of the lightning rather than from several hundred kilometers up in orbit, so that one can correlate the observations of the energetic radiation with details of the thunderstorm characteristics and weather conditions.
An initial catalog of 23 millisecond-scale events has now been accumulated during the first 2 years of TETRA-II operation including time histories, energy spectra, and correlations with radio sferics. Time histories and the gamma-ray-radio correlations show an unexpected evolution of the events over the duration of the bursts, indicating electron acceleration at the lightning leader tips. Of the initial events, 13 were seen in Louisiana, 9 in Panama, and 1 in Puerto Rico. Gamma rays are seen in connection with a variety of different storm types, but apparently only when cloud tops reach 40,000 ft and generally only when hail is present.
Last Modified: 06/20/2019
Modified by: Michael L Cherry
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