| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
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| Initial Amendment Date: | August 31, 2015 |
| Latest Amendment Date: | August 31, 2015 |
| Award Number: | 1532038 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Nicholas Anderson
nanderso@nsf.gov (703)292-4715 AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | September 1, 2015 |
| End Date: | August 31, 2016 (Estimated) |
| Total Intended Award Amount: | $198,952.00 |
| Total Awarded Amount to Date: | $198,952.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
113 FALKNER UNIVERSITY MS US 38677-9704 (662)915-7482 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
University MS US 38677-1848 |
| 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: |
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| 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
Despite decades of lightning research, there is still much to be learned about the initial sparks of a lightning flash and how lightning creates a path through the sky. This award will provide researchers the opportunity to set up an array of electrical sensors in northern Mississippi to collect important data that can be used to investigate and gain a better understanding of the mechanisms that start a lightning flash. Increased understanding of lightning is important due to significant societal impacts that lightning has on people and property each year. The award will also contribute to the education and training of the next generation of scientists through the support of a postdoctoral researcher and a graduate student.
This award will fund the deployment of a suite of electrical sensors at nine different sites across northern Mississippi. Each site will contain an E-charge sensor, a VHF sensor, and a dE/dt sensor. In addition, the PIs will deploy two high speed video cameras, one with the ability to operate at 50,000 frames per second. The instrumentation setup is designed to allow the researchers to address the following questions: 1) What events begin and amplify an initial E-charge (IEC) and how do these events cause the IEC? 2) When and how does the transition from non-conducting air to a hot conducting channel occur? 3) What do initial breakdown pulses of intracloud flashes look like optically and are they similar to initial breakdown pulses of cloud-to-ground flashes? 4) Why do some flashes have multiple sets of IB pulses? 5) Why do some Narrow Bipolar Pulses initiate intracloud flashes while others do not?
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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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.
Lightning is a dangerous and beautiful natural phenomenon. A lightning flash moves electric charge through thin conducting paths (called channels and leaders). However, we do not understand how a lightning flash begins ‘out of thin air’ or how it creates lightning channels in the air, since air is an insulator and does not conduct electricity. In a review titled “The Physics of Lightning,” Dwyer and Uman [2014] state: “The problem of how lightning is initiated inside thunderclouds is not only one of the biggest unsolved problems in lightning physics; it is also probably one of the biggest mysteries in the atmospheric sciences.”
Recent research has shown that each lightning flash seems to begin with a short pulse of radio frequency noise (with a duration of only about 50 millionths of a second), that electric charges begin to move after the pulse, and that a second big pulse is emitted about one thousandth of a second later. However, the peak frequencies and overall shape of the second pulse are different from the first pulse.
This one-year project—named “Lightning Initiation Studies”—was aimed at collecting data from multiple sensors to gain new understanding about the initiation of lightning flashes. Three main sensors looked at lightning initiation at different frequencies simultaneously, with the goal of sorting out how and why the different frequencies occur, and thereby getting a better understanding of the physical mechanisms of lightning initiation.
An array of 7 sensor sites, with each site having all three types of sensors, was deployed in Lafayette and Panola counties in north Mississippi. Having seven sites meant that the positions of fast pulses associated with lightning initiation can be determined by using a time-of-arrival technique. Data were collected on 31 storm days in July and August of 2016, and data from several thousand lightning flashes were recorded. Analysis of these data is underway.
In summary, this NSF award was successful in providing new data to help understand the mysteries of how lightning flashes begin. Three graduate students and one post-doctoral researcher were actively involved in all aspects of the project, along with the PI and co-PI.
Last Modified: 11/29/2016
Modified by: Thomas C Marshall
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