A5033983693- Lightning and Electromagnetic Phenomena
- Fire effects on ecosystems
- Ionosphere and magnetosphere dynamics
- Earthquake Detection and Analysis
- High voltage insulation and dielectric phenomena
- Meteorological Phenomena and Simulations
- Electrical Fault Detection and Protection
- Advanced Optical Sensing Technologies
- Plant responses to water stress
- Seismic Waves and Analysis
- Power Line Communications and Noise
- Atmospheric aerosols and clouds
- Thermal Analysis in Power Transmission
- Solar and Space Plasma Dynamics
- Power Transformer Diagnostics and Insulation
- Astrophysics and Cosmic Phenomena
- Electrostatic Discharge in Electronics
- Soil Moisture and Remote Sensing
- Precipitation Measurement and Analysis
- Tree Root and Stability Studies
- Combustion and Detonation Processes
- Fire Detection and Safety Systems
- Electromagnetic Compatibility and Noise Suppression
- Advanced Decision-Making Techniques
- Plasma Diagnostics and Applications
New Mexico Institute of Mining and Technology
2015-2024
Earth Networks (United States)
2023
Alaska Volcano Observatory
2007
University of Alaska Fairbanks
2007
Colorado State University
2004
NOAA National Weather Service
2004
South Dakota School of Mines and Technology
2004
NSF National Center for Atmospheric Research
2004
NOAA National Severe Storms Laboratory
2004
Geophysical Laboratory
1999
A GPS‐based system has been developed that accurately locates the sources of VHF radiation from lightning discharges in three spatial dimensions and time. The observations are found to reflect basic charge structure electrified storms. Observations have also obtained a distinct type energetic discharge referred as positive bipolar breakdown, recently identified source trans‐ionospheric pulse pairs (TIPPs) observed by satellites space. breakdown confirmed occur between main negative upper...
The location accuracy of the New Mexico Tech Lightning Mapping Array (LMA) has been investigated experimentally using sounding balloon measurements, airplane tracks, and observations distant storms. We have also developed simple geometric models for estimating uncertainty sources both over outside network. model results are found to be a good estimator observed errors agree with covariance estimates uncertainties obtained from least squares solution technique. Sources network located an 6–12...
Sources of charge for the individual strokes four multiple‐stroke flashes to ground have been determined, using measurements electrostatic field change obtained at eight locations on beneath storm. The resulting compared 3‐cm radar precipitation structure in changes were found be reasonably consistent with lowering a localized or spherically symmetric cloud. centers successive each flash developed over large horizontal distances within cloud, up 8 km, more less constant elevation between −9°...
A long-standing but fundamental question in lightning studies concerns how is initiated inside storms, given the absence of physical conductors. The issue has revolved around whether discharges are solely by conventional dielectric breakdown or involve relativistic runaway electron processes. Here we report observations a relatively unknown type discharge, called fast positive breakdown, that cause high-power known as narrow bipolar events. found to have wide range strengths and initiating...
A detailed study of the complete sequence VHF radiation events during intracloud (IC) flashes in Florida has shown that IC often have a bilevel structure connected by single upward channel. The lower and upper level channels appear to correspond main negative positive charge regions storm, respectively. are characterized active final stages, each comprising about half overall flash duration. During stage, is transported cloud, first as result initial breakdown, which establishes channel,...
Lightning charges, locations, and currents have been determined for 12 flashes from four winter storms observed on the Hokuriku coast of Japan during December 1977 through January 1978. Additional data is available a total eight storms. The heights magnitudes charges in strokes‐to‐ground were calculated simultaneous measurements electric field changes made at seven stations covering an area about 150 km 2 . Discharges lowering positive charge to earth often exhibit large continuing (>10 4...
Radio frequency observations of cloud‐to‐ground lightning in Florida have been analyzed to document a number features the lightning. The made using an interferometer system which determined direction radiation as function time during close discharges. Observations are presented for about 50 radiating events five multiple‐stroke, normal‐polarity flashes ground. results confirm and extend similar study New Mexico by Rhodes et al. (1994). Dart leaders, in‐cloud “K” events, attempted leaders...
Observations of radio emissions from thunderstorms were made during the summer 1996 using two arrays sensors located in northern New Mexico. The first array consisted three fast electric field change meters separated by distances 30 to 230 km. second broadband (3 MHz) HF data acquisition systems 6 13 Differences signal times arrival at multiple stations used locate sources received signals. Relative reflections ionosphere and Earth determine source heights. A distinct class short‐duration...
Great Plains storms are known for their ability to produce severe weather. They also prodigious producers of lightning; just how has been vividly illustrated by observations in central Oklahoma with a new Global Positioning System (GPS)‐based lightning mapping system.The useful not only studying storm electrification but provide valuable indicator structure and intensity. The system maps three spatial dimensions measuring the times at which impulsive VHF radiation events arrive network...
Three‐dimensional lightning mapping observations have been used to estimate the peak source powers radiated by individual VHF events of discharges. The vary from minimum locatable values about 1 W typically up 10–30 kW or more in 60–66 MHz passband receivers. An energetic positive bipolar event excess 300 k power. strongest radiation sources tended be observed upper part storms, corresponding charge region, where breakdown is negative polarity. results illustrate bidirectional nature...
During May–July 2000, the Severe Thunderstorm Electrification and Precipitation Study (STEPS) occurred in High Plains, near Colorado–Kansas border. STEPS aimed to achieve a better understanding of interactions between kinematics, precipitation, electrification severe thunderstorms. Specific scientific objectives included 1) apparent major differences precipitation output from supercells that have led them being classified as low (LP), classic or medium high precipitation; 2) lightning...
The field program of the Thunderstorm Electrification and Lightning Experiment (TELEX) took place in central Oklahoma, May–June 2003 2004. It aimed to improve understanding interrelationships among microphysics, kinematics, electrification, lightning a broad spectrum storms, particularly squall lines storms whose electrical structure is inverted from usual vertical polarity. was built around two permanent facilities: KOUN polarimetric radar Oklahoma Mapping Array. In addition, balloon-borne...
The VHF Broadband Digital Interferometer developed by Osaka University has been improved to allow continuous sampling over the entire duration of a lightning flash and utilize generalized cross-correlation technique for determining source directions. Time series waveforms 20–80 MHz signals received at three orthogonally located antennas are continuously digitized multisecond intervals, as opposed sequences short-duration triggers. Because coherent nature measurements, radiation sources down...
Abstract Thunderstorms are natural laboratories for studying electrical discharges in air, where the vast temporal, spatial, and energy scales available can spawn surprising phenomena that reveal deficiencies our understanding of dielectric breakdown. Recent discoveries, such as sprites, jets, terrestrial gamma ray flashes, fast positive breakdown, highlight diversity complex thunderstorms produce, point to possibility breakdown/discharge mechanisms beyond breakdown theory based mainly on...
Abstract A database consisting of approximately 4000 storm observations has been objectively analyzed to determine environmental characteristics that produce high radar reflectivities above the freezing level, large total lightning flash rates on order 10 flashes per minute, and anomalous vertical charge structures (most notably, dominant midlevel positive charge). The is drawn from four regions United States featuring distinct environments, each with coinciding Lightning Mapping Array (LMA)...
Three‐dimensional lightning mapping observations are compared to cloud charge structures and electric potential profiles inferred from balloon soundings of field in New Mexico mountain thunderstorms. For six individual intracloud cloud‐to‐ground flashes for a sequence 36 one storm, the comparisons consistently show good agreement between altitudes horizontal channels extrema or wells. Lightning appear deposit opposite polarity relatively localized volumes within preexisting lower positive,...
High speed video of sprites show that they are typically initiated at an altitude about 75 km and usually develop simultaneously upwards downwards from the point origin with initial columniform shape. The development appears to be dominated by corona streamers velocities in excess 10 7 m/s. Many observed characteristics consistent a conventional breakdown mechanism for both sprite initiation development.
A radio interferometer system is described which utilizes multiple baselines to determine the direction of lightning radiation sources with an angular resolution a few degrees and microsecond time resolution. An interactive graphics analysis procedure used remove fringe ambiguities from data reveal structure development discharges inside storm. Radiation source directions electric field waveforms have been analyzed for different types breakdown events two flashes. These include initial K...
3‐dimensional lightning mapping observations obtained in central Oklahoma by the New Mexico Tech Lightning Mapping Array (LMA) have been compared with optical of discharges from space NASA's Imaging Sensor (LIS). Excellent spatial and temporal correlations were between two sets observations. All seen LIS mapped LMA. Most detected events associated channels that extended into upper part storm. Cloud‐to‐ground confined to mid‐ lower‐altitudes less well than intracloud discharges, tended be...
Abstract Balloon soundings were made through two supercell storms during the Severe Thunderstorm Electrification and Precipitation Study (STEPS) in summer 2000. Instruments measured vector electric field, temperature, pressure, relative humidity, balloon location. For first time, penetrated both strong updraft rainy downdraft region of same storm. In storms, had fewer vertically separated charge regions than found near downdraft, updraft’s lowest was elevated higher, its bottom being 40-dBZ...
In situ electric field (E) measurements and inferred lightning initiation locations of three cloud‐to‐ground flashes are used to identify a thunderstorm region in which the preflash E exceeded threshold for runaway breakdown. The maximum measured was 186 kV m −1 at 5.77 km altitude, electrons is equivalent 370 sea level; this value ∼130% estimated an avalanche electrons. addition, volume where be 1–4 3 , with vertical depth about 1000 m. At least within part characteristic scale height...
Multistation electric field change measurements have confirmed earlier findings that lightning ground strokes in the Hokuriku winter storms generally lower positive charge to earth. Only one out of eight flashes involved ‘normal’ negative commonly found summer storms. The mode discharge appears favor continuing current type: twelve were followed by a current. Despite ‘abnormal’ stroke polarity, appear exhibit normal dipolar structure (positive uppermost), although dipole is apparently...