310 Larsen Hall
Gainesville, Florida 32611
Recent Research Highlights from the ICLRT at Camp Blanding
By Martin A. Uman, Distinguished Professor, UF ECE
Dr. Martin A. Uman – Short Biography
Martin A. Uman received his bachelor’s, master’s, and doctoral degrees in Electrical Engineering from Princeton University, the latter in 1961.
Dr. Uman’s first position after graduate school was Associate Professor of Electrical Engineering at the University of Arizona where he first became interested in lightning.
In 1965, he joined the staff of the Westinghouse Research Laboratories in Pittsburgh where he studied the physical and electromagnetic aspects of lightning and long laboratory sparks. Dr. Uman became Professor at the University of Florida in 1971. He has been Director of the UF Lightning Research Laboratory since 1972. He co-founded and served as President of Lightning Location and Protection, Inc. (LLP) from 1975 to 1983. LLP, now a division of Vaisala, developed the lightning locating instrumentation that became the basis for the U. S. National Lightning Detection Network (NLDN). From 1991 to 2003, Dr. Uman was Professor and Chair of the Department of Electrical and Computer Engineering at the University of Florida. Presently, he holds the rank of Distinguished Professor.
Dr. Uman is generally acknowledged to be one of the world’s leading authorities on lightning. He is probably best known for his work in lightning modeling: the application of electromagnetic field theory to the description of various lightning processes. That work, in addition to providing a better understanding of lightning in general, has had a number of important practical spinoffs, the most notable being the LLP lightning locating system and the redefinition of several important lightning characteristics relative to hazard protection. Dr. Uman has authored or co-authored five books on the subject of lightning (the latest in 2008) and a book on plasma physics. He has written seventeen book chapters and encyclopedia articles on lightning, and he has published over 250 papers in reviewed journals and nearly 300 in non-reviewed journals and conference proceedings. He holds seven patents, six in the area of lightning detection and location.
Dr. Uman was the recipient of the 2010 International Conference on Lightning Protection’s Karl Berger Award “for distinguished achievements in the science and engineering of lightning research, developing new fields in theory and practice, modeling and measurements”. Dr. Uman was awarded the 2001 American Geophysical Union John Adam Fleming Medal for original research and technical leadership in geomagnetism, atmospheric electricity, space science, aeronomy, and related sciences for “outstanding contribution to the description and understanding of electricity and magnetism of the earth and its atmosphere.” Dr. Uman was the recipient of the Heinrich Hertz Medal in 1996 by the Institute of Electrical and Electronic Engineers (IEEE) for “…outstanding contributions to the understanding of lightning electromagnetics and its application to lightning detection and protection.” He was named the Florida Scientist of the Year by the Florida Academy of Sciences for 1990 and the 1988-89 University of Florida Teacher-Scholar of the Year, the highest UF faculty award. He is a Fellow of three professional organizations: the IEEE, the American Geophysical Union, and the American Meteorological Society. Other awards include NASA’s 1992 and 1996 Group Achievement Awards to the Galileo Probe Spacecraft Team and three IEEE prize paper awards: the 2001 IEEE Power Engineering Society Surge Protective Devices Committee Prize Paper Award; the Electromagnetic Compatibility Society 1982 Transactions Prize Paper Award; and the Industry Applications Society, Industrial and Power Systems Department, 1994 Ralph H. Lee Prize Paper Award.
The International Center for Lightning Research and Testing at Camp Blanding (ICLRT)
is a research facility located in north-central Florida where both natural and “triggered” lightning have been studied since 1994. Triggered lightning is upward-initiated lightning similar to most lightning from very tall structures, and is achieved by elevating a grounded wire to a height of the order of 100 m in a time of the order of 1 sec underneath thunderstorm charge. Triggered lightning exhibits many of the processes characteristic of natural lightning and hence allows those processes to be studied in an efficient manner. In this talk, we review selected ICLRT research aimed at understanding triggered lightning itself and at understanding four selected natural lightning processes via triggered lightning measurements. We concentrate on “firsts” and “significant advancements” made at the I CLRT during the last two decades. During most of that period, the ICLRT was jointly operated by the University of Florida and the Florida Institute of Technology. We focus on the five areas of study noted below, but we do not attempt complete coverage of any of these five topics, only the presentation of “firsts” and “significant advancements” along with selected journal papers that have led to further research at the ICLRT and elsewhere:
1. Triggered Lightning Phenomenology (How Does it Work?) [Biagi et al.
2011a,b, Hill et al. 2012, 2013, Pilkey et al. 2013, 2014, Ngin et al. 2013, 2014, MacGorman et
2. Negative Leader Step Formation [Biagi et al. 2009, 2010, Gamerota et al. 2014,
Wang et al. 2016];
3. X-ray Emission from Leaders [Dwyer et al. 2003, 2004a, 2005,2011,
Howard et al. 2008, Hill et al. 2012];
4. Ground-Attachment Process [Wang et al. 1999,2014,
Jerauld et al. 2007, Biagi et al. 2009, Howard et al. 2010, Hill et al. 2016] and;
Gamma Ray Flashes (TGF’s) Observed at Ground-level During Triggered Lightning [Dwyer et
al. 2004b, Hare et al. 20 16].
Biagi, C. J., D. M. Jordan, M. A. Uman, J. D. Hill, W. H. Beasley, and J. Howard, (2009), High-speed Video Observations of Rocket-and-Wire Initiated Lightning, Geophys. Res. Lett. Vol. 36, LI5801, doi: 10.1 029/2009GL038525
Biagi, C. J., M.A. Uman, J D. Hill, D. M. Jordan, V. A. Rakov, and J. Dwyer, (2010), Observations of Stepping Mechanisms in a Rocket-and-Wire Triggered Lightning Flash, J. Geophys. Res. Vol. 115, D23215,
doi: 1 0.1 029/201 OJDO 14616
Biagi, C. J., M. A. Uman, J. Gopalakrishnan, J. D. Hill, V. A. Rakov, T. Ngin, and D. M. Jordan, (2011a),
Determination of the Electric Field Intensity and Space Charge Density versus Height Prior to Triggering
Lightning, J. Geophys. Res. Vol. 116, D 1520 1, doi: 10.1 029/2011 JDO 1571 0
Biagi, C. J., M. A. Uman, J. D. Hill, and D. M. Jordan, (2011b), Observations of the initial, upward-propagating,
positive leader steps in a rocket-and-wire triggered lightning discharge, Geophys. Res. Lett. Vol. 38,
Dwyer, J. R., M.A. Uman, H. K. Rassoul, M. Al-Dayeh, E. L. Caraway, J. Jerauld, V. A. Rakov, D. M. Jordan, K. J.
Rambo, V. Corbin and B. Wright, (2003), Energetic Radiation Produced by Rocket-Triggered Lightning,
Science 31, Vol. 299, doi: 10.1126/Science.l078940
Dwyer, J. R., H. K. Rassoul, M. AJ-Dayeh, L. Caraway, B. Wright, A.Chrest, M. A. Uman, V. A. Rakov, K. J.
Rambo, D. M. Jordan, J. Jerauld and C. Smyth, (2004a), Measurements of X-ray Emission from RocketTriggered
Lightning, Geophys. Res. Lett. Vol. 31, L05118, doi: 10.1 029/2003GLO 18770
Dwyer, J. R., H. K. Rassoul, M. Al-Dayeh, L. Caraway, B. Wright, A. Chrest, M.A. Uman, V. A. Rakov, K. J.
Rambo, D. M. Jordan, J. Jerauld, and C. Smyth, (2004b), A Ground-level Gamma Ray Burst Observed in
Association with Rocket-Triggered Lightning, Geophys. Res. Lett. Vol. 31, L05119,
doi: 10.1 029/2003GLO 18771
Dwyer, J. R., H. K. Rassoul, M. Al-Dayeh, E. L. Caraway, A. Chrest, B. Wright, E. Kozak, J. Jerauld, M.A. Uman,
V. A. Rakov, D. M. Jordan, and K.J. Rambo, (2005), X-Ray Bursts Associated with Leader Steps in Cloud-toGround
Lightning, Geophys. Res. Lett. Vol. 32, L01803, doi:10.1029/2004GL021782
Dwyer, J. R., M. Schaal, H. K. Rassoul, M.A. Uman, D. M. Jordan and J.D. Hill, (2011), High-Speed X-ray Images
ofTriggered Lightning Dart Leaders, J. Geophys. Res., Vol. I16, D20208, doi:10.1029/2011JD015973
Gamerota, W. R., V. P. Idone, M. A. Uman, T. Ngin, J. T., Pilkey and D. M. Jordan, (2014), Dart-Stepped-Leader
Step Formation in Triggered Lightning, Geophys. Res. Lett., 41,2204-2211, doi:I0.1002/2014GL059627
Hare, B. M., M.A. Uman, J. R. Dwyer, D. M. Jordan, M.l. Biggerstaff, J. A. Caicedo, F. L. Carvalho, R. A. Wilkes,
D. A. Kotovsky, W. R. Gamerota, J. T. Pilkey, T. K. Ngin, R. C. Moore, H. K. Rassoul, S. A. Cummer, J. E.
Grove, A. Nag, D.P. Betten, A. Bozarth, (20I6), Ground-Level Observation of a Terrestrial Gamma Ray Flash
Initiated by a Triggered Lightning, J. Geophys. Res. Atmos. Doi: 10.1 002/20 15JD02442
Hill, J.D., J. T. Pilkey, M.A. Uman, D. M. Jordan, W. Rison and P.R. Krehbiel, (20I2), Geometrical and Electrical
Characteristics of the Initial Stage in Florida Triggered Lightning, Geophys. Res. Lett. Vol. 39, L09807,
doi: 1 0.1 029/20 12GL051932
Hill, J. D., J. T. Pilkey, M. A. Uman, D. M. Jordan, W. Rison, P. R. Krehbiel, M. I. Biggerstaff, P. Hyland, and R.
Blakeslee, (20I3), Correlated Lightning Mapping Array and Radar Observations of the Initial Stage of Three
Sequentially Triggered Florida Lightning Discharges, J. Geophys. Res. Vol. 118, 8460-848I,
doi: I 0.1 002/jgrd.50660
Hill, J. D., M. A. Uman, D. M. Jordan, T. Ngin, W. R. Gamerota, J. T. Pilkey and J. Caicedo, (20I6), The
Attachment Process of Rocket-Triggered Lightning Dart-Stepped Leaders, J. Geophys. Res. Atmos., 121, 853-
87I, doi: 10.1002/20 15JD024269
Howard, J., M.A. Uman, J. R. Dwyer, J. D. Hill, C. J. Biagi, Z. Saleh, J. Jerauld, and H. K. Rassoul, (2008), CoLocation
of Lightning Leader X-Ray and Electric Field Change Sources, Geophys. Res. Lett. Vol. 35, L13817,
doi: 1 0.1 029/2008GL034134
Howard, J., M.A. Uman, C. J. Biagi, J.D. Hill, J. Jerauld, V. A. Rakov, J. R. Dwyer, Z. Saleh, and H. K. Rassoul,
(2010), RF and X-Ray Source Locations During the Lightning Attachment Process, J. Geophys. Res., Vol. 115,
006204, doi: I 0.1 029/2009JDO 12055
Jerauld, J., M. A. Uman, V. A. Rakov, K. J. Rambo, and G. H. Schnetzer, (2007), Insights Into the Ground
Attachment of Natural Lightning Gained from an Unusual Triggered Lightning Stroke, J. Geophys. Res. 112,
Dl3113, doi: 10.1029/2006JD007682
MacGorman, D. R., M. I Biggerstaff, S. Waugh, J. T. Pilkey, M. A. Uman, D. M. Jordan, T. Ngin, W. R. Gamerota,
G. Carrie, and P. Hyland, (2015), Coordinated Lightning, Balloon-borne Electric Field, and Polarimetric Radar
Observations ofTriggered Lightning Flashes in North Florida, Geophys. Res. Lett.doi:10.1002/2015GL064203
Ngin, T., M. A. Uman, J. D. Hill, J. T. Pilkey, W. R. Gamerota, D. M. Jordan and R. C. Olsen, III, (2013),
Measurement and Analysis of Ground-Level Electric Fields and Wire-Based Current During the Rocket-andWire
Lightning Triggering Process, J. Geophys. Res. Vol. 118, 10,041-10,055, doi: 10.1 002/jgrd.50774
Ngin, T., M.A. Uman, J.D. Hill, R. C. Olsen III, J. T. Pilkey, W. R. Gamerota, and D. M. Jordan, (2014), Does the
Lightning Current Go To Zero Between Ground Strokes? Is there a “Current Cutoff’?, Geophys. Res. Lett. 4I,
3266-3273, doi: I 0.1002/20 14GL05960 I
Pilkey, J. T., M. A. Uman, J. D. Hill, T. Ngin, W. R. Gamerota, D. M. Jordan, W. Rison, P. R. Krehbiel, H. E.
Edens, M. I. Biggerstaff, and P. Hyland, (2013), Rocket-and-Wire Triggered Lightning, J. Geophys. Res.
Atmos., doi: 10.1 002/JD02050 1
Pilkey, J. T., M.A. Uman, J. D. Hill, T. Ngin, W. R. Gamerota, D. M. Jordan, J. Caicedo, and B. Hare, (2014),
Rocket-Triggered Lightning Propagation Paths Relative to Preceding Natural Lightning Activity and Inferred
Cloud Charge, J. Geophys. Res. Atmos. 119, 13,427-13,456, doi:10.I002/2014JD022I39
Wang, D., V. A. Rakov, M.A. Uman, N. Takagi, T. Watanabe, D. E. Crawford, K. J. Rambo, G. H. Schnetzer, R. J.
Fisher, and Z.-1. Kawasaki (1999), Attachment Process in Rocket-Triggered Lightning Strokes, J. Geophys.
Res. 104, 2143-2150
Wang, D., N. Takagi, W. R. Gamerota, M. A. Uman, J. T. Pilkey, T. Ngin, D. M. Jordan, S. Mallick, and V. A.
Rakov, (2014), Lightning Attachment Processes of an “Anomalous” Triggered Lightning Discharge, J.
Geophys. Res. Atmos.,doi:10.1002/2013JD020787
Wang, D., N. Takagi, M.A. Uman, and D. M. Jordan, (2016), Luminosity Progression in Dart-Stepped Leader Step
Formation, J. Geophys. Res. Atmos. Doi: 10.1002/20 16JD025813