Lightning and surge protection of large ground facilities

NASA Astrophysics Data System (ADS)

Stringfellow, Michael F.

1988-04-01

The vulnerability of large ground facilities to direct lightning strikes and to lightning-induced overvoltages on the power distribution, telephone and data communication lines are discussed. Advanced electrogeometric modeling is used for the calculation of direct strikes to overhead power lines, buildings, vehicles and objects within the facility. Possible modes of damage, injury and loss are discussed. Some appropriate protection methods for overhead power lines, structures, vehicles and aircraft are suggested. Methods to mitigate the effects of transients on overhead and underground power systems as well as within buildings and other structures are recommended. The specification and location of low-voltage surge suppressors for the protection of vulnerable hardware such as computers, telecommunication equipment and radar installations are considered. The advantages and disadvantages of commonly used grounding techniques, such as single point, multiple and isolated grounds are compared. An example is given of the expected distribution of lightning flashes to a large airport, its buildings, structures and facilities, as well as to vehicles on the ground.

RSRM top hat cover simulator lightning test, volume 2. Appendix A: Resistance measurements. Appendix B: Lightning test data plots

NASA Technical Reports Server (NTRS)

1990-01-01

Resistance measurements are given in graphical for when a simulated lightning discharge strikes on an exposed top hat cover simulator. The test sequence was to measure the electric and magnetic fields induced inside a redesigned solid rocket motor case.

Lightning testing at the subsystem level

NASA Technical Reports Server (NTRS)

Luteran, Frank

1991-01-01

Testing at the subsystem or black box level for lightning hardness is required if system hardness is to be assured at the system level. The often applied philosophy of lighting testing only at the system level leads to extensive end of the line design changes which result in excessive costs and time delays. In order to perform testing at the subsystem level two important factors must be defined to make the testing simulation meaningful. The first factor is the definition of the test stimulus appropriate to the subsystem level. Application of system level stimulations to the subsystem level usually leads to significant overdesign of the subsystem which is not necessary and may impair normal subsystem performance. The second factor is the availability of test equipment needed to provide the subsystem level lightning stimulation. Equipment for testing at this level should be portable or at least movable to enable efficient testing in a design laboratory environment. Large fixed test installations for system level tests are not readily available for use by the design engineers at the subsystem level and usually require special operating skills. The two factors, stimulation level and test equipment availability, must be evaluated together in order to produce a practical, workable test standard. The neglect or subordination of either factor will guarantee failure in generating the standard. It is not unusual to hear that test standards or specifications are waived because a specified stimulation level cannot be accomplished by in-house or independent test facilities. Determination of subsystem lightning simulation level requires a knowledge and evaluation of field coupling modes, peak and median levels of voltages and currents, bandwidths, and repetition rates. Practical limitations on test systems may require tradeoffs in lightning stimulation parameters in order to build practical test equipment. Peak power levels that can be generated at specified bandwidths with standard electrical components must be considered in the design and costing of the test system. Stimulation tests equipment and test methods are closely related and must be considered a test system for lightning simulation. A non-perfect specification that can be reliably and repeatedly applied at the subsystem test level is more desirable than a perfect specification that cannot be applied at all.

Measuring Method for Lightning Channel Temperature.

PubMed

Li, X; Zhang, J; Chen, L; Xue, Q; Zhu, R

2016-09-26

In this paper, we demonstrate the temperature of lightning channel utilizing the theory of lightning spectra and the model of local thermodynamic equilibrium (LTE). The impulse current generator platform (ICGS) was used to simulate the lightning discharge channel, and the spectral energy of infrared spectroscopy (930 nm) and the visible spectroscopy (648.2 nm) of the simulated lightning has been calculated. Results indicate that the peaks of luminous intensity of both infrared and visible spectra increase with the lightning current intensity in range of 5-50 kA. Based on the results, the temperature of the lightning channel is derived to be 6140.8-10424 K. Moreover, the temperature of the channel is approximately exponential to the lightning current intensity, which shows good agreement with that of the natural lightning cases.

Measuring Method for Lightning Channel Temperature

NASA Astrophysics Data System (ADS)

Li, X.; Zhang, J.; Chen, L.; Xue, Q.; Zhu, R.

2016-09-01

In this paper, we demonstrate the temperature of lightning channel utilizing the theory of lightning spectra and the model of local thermodynamic equilibrium (LTE). The impulse current generator platform (ICGS) was used to simulate the lightning discharge channel, and the spectral energy of infrared spectroscopy (930 nm) and the visible spectroscopy (648.2 nm) of the simulated lightning has been calculated. Results indicate that the peaks of luminous intensity of both infrared and visible spectra increase with the lightning current intensity in range of 5-50 kA. Based on the results, the temperature of the lightning channel is derived to be 6140.8-10424 K. Moreover, the temperature of the channel is approximately exponential to the lightning current intensity, which shows good agreement with that of the natural lightning cases.

A simple lightning assimilation technique for improving ...

EPA Pesticide Factsheets

Convective rainfall is often a large source of error in retrospective modeling applications. In particular, positive rainfall biases commonly exist during summer months due to overactive convective parameterizations. In this study, lightning assimilation was applied in the Kain-Fritsch (KF) convective scheme to improve retrospective simulations using the Weather Research and Forecasting (WRF) model. The assimilation method has a straightforward approach: force KF deep convection where lightning is observed and, optionally, suppress deep convection where lightning is absent. WRF simulations were made with and without lightning assimilation over the continental United States for July 2012, July 2013, and January 2013. The simulations were evaluated against NCEP stage-IV precipitation data and MADIS near-surface meteorological observations. In general, the use of lightning assimilation considerably improves the simulation of summertime rainfall. For example, the July 2012 monthly averaged bias of 6 h accumulated rainfall is reduced from 0.54 to 0.07 mm and the spatial correlation is increased from 0.21 to 0.43 when lightning assimilation is used. Statistical measures of near-surface meteorological variables also are improved. Consistent improvements also are seen for the July 2013 case. These results suggest that this lightning assimilation technique has the potential to substantially improve simulation of warm-season rainfall in retrospective WRF applications. The

A Simple Lightning Assimilation Technique For Improving ...

EPA Pesticide Factsheets

Convective rainfall is often a large source of error in retrospective modeling applications. In particular, positive rainfall biases commonly exist during summer months due to overactive convective parameterizations. In this study, lightning assimilation was applied in the Kain-Fritsch (KF) convective scheme to improve retrospective simulations using the Weather Research and Forecasting (WRF) model. The assimilation method has a straightforward approach: Force KF deep convection where lightning is observed and, optionally, suppress deep convection where lightning is absent. WRF simulations were made with and without lightning assimilation over the continental United States for July 2012, July 2013, and January 2013. The simulations were evaluated against NCEP stage-IV precipitation data and MADIS near-surface meteorological observations. In general, the use of lightning assimilation considerably improves the simulation of summertime rainfall. For example, the July 2012 monthly-averaged bias of 6-h accumulated rainfall is reduced from 0.54 mm to 0.07 mm and the spatial correlation is increased from 0.21 to 0.43 when lightning assimilation is used. Statistical measures of near-surface meteorological variables also are improved. Consistent improvements also are seen for the July 2013 case. These results suggest that this lightning assimilation technique has the potential to substantially improve simulation of warm-season rainfall in retrospective WRF appli

Lightning Technology: Proceedings of a Technical Symposium

NASA Technical Reports Server (NTRS)

1980-01-01

Several facets of lightning technology are considered including phenomenology, measurement, detection, protection, interaction, and testing. Lightning electromagnetics, protection of ground systems, and simulated lightning testing are emphasized. The lightning-instrumented F-106 aircraft is described.

Lightning Protection Certification for High Explosives Facilities at Lawrence Livermore National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clancy, T J; Brown, C G; Ong, M M

2006-01-11

Presented here is an innovation in lighting safety certification, and a description of its implementation for high explosives processing and storage facilities at Lawrence Livermore National Laboratory. Lightning rods have proven useful in the protection of wooden structures; however, modern structures made of rebar, concrete, and the like, require fresh thinking. Our process involves a rigorous and unique approach to lightning safety for modern buildings, where the internal voltages and currents are quantified and the risk assessed. To follow are the main technical aspects of lightning protection for modern structures and these methods comply with the requirements of the Nationalmore » Fire Protection Association, the National Electrical Code, and the Department of Energy [1][2]. At the date of this release, we have certified over 70 HE processing and storage cells at our Site 300 facility.« less

Low-frequency RF Coupling To Unconventional (Fat Unbalanced) Dipoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ong, M M; Brown, C G; Perkins, M P

2010-12-07

The report explains radio frequency (RF) coupling to unconventional dipole antennas. Normal dipoles have thin equal length arms that operate at maximum efficiency around resonance frequencies. In some applications like high-explosive (HE) safety analysis, structures similar to dipoles with ''fat'' unequal length arms must be evaluated for indirect-lightning effects. An example is shown where a metal drum-shaped container with HE forms one arm and the detonator cable acts as the other. Even if the HE is in a facility converted into a ''Faraday cage'', a lightning strike to the facility could still produce electric fields inside. The detonator cable concentratesmore » the electric field and carries the energy into the detonator, potentially creating a hazard. This electromagnetic (EM) field coupling of lightning energy is the indirect effect of a lightning strike. In practice, ''Faraday cages'' are formed by the rebar of the concrete facilities. The individual rebar rods in the roof, walls and floor are normally electrically connected because of the construction technique of using metal wire to tie the pieces together. There are two additional requirements for a good cage. (1) The roof-wall joint and the wall-floor joint must be electrically attached. (2) All metallic penetrations into the facility must also be electrically connected to the rebar. In this report, it is assumed that these conditions have been met, and there is no arcing in the facility structure. Many types of detonators have metal ''cups'' that contain the explosives and thin electrical initiating wires, called bridge wires mounted between two pins. The pins are connected to the detonator cable. The area of concern is between the pins supporting the bridge wire and the metal cup forming the outside of the detonator. Detonator cables usually have two wires, and in this example, both wires generated the same voltage at the detonator bridge wire. This is called the common-mode voltage. The explosive component inside a detonator is relatively sensitive, and any electrical arc is a concern. In a safety analysis, the pin-to-cup voltage, i.e., detonator voltage, must be calculated to decide if an arc will form. If the electric field is known, the voltage between any two points is simply the integral of the field along a line between the points. Eq. 1.1. For simplicity, it is assumed that the electric field and dipole elements are aligned. Calculating the induced detonator voltage is more complex because of the field concentration caused by metal components. If the detonator cup is not electrically connected to the metal HE container, the portion of the voltage generated by the dipole at the detonator will divide between the container-to-cup and cup-to-pin gaps. The gap voltages are determined by their capacitances. As a simplification, it will be assumed the cup is electrically attached, short circuited, to the HE container. The electrical field in the pin-to-cup area is determined by the field near the dipole, the length of the dipole, the shape of the arms, and the orientation of the arms. Given the characteristics of a lightning strike and the inductance of the facility, the electric fields in the ''Faraday cage'' can be calculated. The important parameters for determining the voltage in an empty facility are the inductance of the rebars and the rate of change of the current, Eq. 1.3. The internal electric fields are directly related to the facility voltages, however, the electric fields in the pin-to-cup space is much higher than the facility fields because the antenna will concentrate the fields covered by the arms. Because the lightning current rise-time is different for every strike, the maximum electric field and the induced detonator voltage should be described by probability distributions. For pedantic purposes, the peak field in the simulations will be simply set to 1 V/m. Lightning induced detonator voltages can be calculated by scaling up with the facility fields. Any metal object around the explosives, such as a work stand, will also distort the electric fields. A computer simulation of the electric fields in a facility with a work stand and HE container is shown. In this configuration, the work stand is grounded, and the intensity of field around the HE (denoted in dark blue) is reduced relative to the rest of the work bay (denoted lighter blue). The area above work stand posts has much higher fields indicated by red. The fields on top of the container are also affected. Without an understanding of how the electric fields are distributed near the detonator cable and container, it is not possible to calculate the induced detonator voltage. The average lightning current has rise- and fall-times of 3 us and 50 us respectively, and this translates to a wavelength that is long when compared with the length of the HE container or detonator cable.« less

Measuring Method for Lightning Channel Temperature

PubMed Central

Li, X.; Zhang, J.; Chen, L.; Xue, Q.; Zhu, R.

2016-01-01

In this paper, we demonstrate the temperature of lightning channel utilizing the theory of lightning spectra and the model of local thermodynamic equilibrium (LTE). The impulse current generator platform (ICGS) was used to simulate the lightning discharge channel, and the spectral energy of infrared spectroscopy (930 nm) and the visible spectroscopy (648.2 nm) of the simulated lightning has been calculated. Results indicate that the peaks of luminous intensity of both infrared and visible spectra increase with the lightning current intensity in range of 5–50 kA. Based on the results, the temperature of the lightning channel is derived to be 6140.8–10424 K. Moreover, the temperature of the channel is approximately exponential to the lightning current intensity, which shows good agreement with that of the natural lightning cases. PMID:27665937

Update Direct-Strike Lightning Environment for Stockpile-to-Target Sequence: Supplement LLNL Subcontract #B568621 Lightning Protection at the Yucca Mountain Waste Storage Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uman, M A

2008-10-09

The University of Florida has surveyed all relevant publications reporting lightning damage to metals, metals which could be used as components of storage containers for nuclear waste materials. We show that even the most severe lightning could not penetrate the stainless steel thicknesses proposed for nuclear waste storage casks.

The 1991 International Aerospace and Ground Conference on Lightning and Static Electricity, volume 2

NASA Technical Reports Server (NTRS)

1991-01-01

The proceedings of the conference are reported. The conference focussed on lightning protection, detection, and forecasting. The conference was divided into 26 sessions based on research in lightning, static electricity, modeling, and mapping. These sessions spanned the spectrum from basic science to engineering, concentrating on lightning prediction and detection and on safety for ground facilities, aircraft, and aerospace vehicles.

Exploring the Production of NOx by Lightning and Its Impact on Tropospheric Ozone

NASA Technical Reports Server (NTRS)

Gillani, Noor; Koshak, William; Biazar, Arastoo; Doty, Kevin; Mahon, Robert; Newchurch, Michael; Byun, Daewon; Emmons, Louisa

2006-01-01

Our quantitative understanding of free tropospheric (FT) chemistry is quite poor. State-of-the-art regional air quality models (e.g., US EPA's CMAQ) perform very poorly in simulating FT chemistry, with Uniform ozone around 70 ppb throughout the FT in summer, while ozonesonde data show much higher levels of ozone and much spatial-temporal structure. Such models completely neglect lightning-NOx (LNOx) emissions (the most significant source of NOx in the FT), and also contain large uncertainties in the specifications of intercontinental transport, stratosphere-troposphere exchange (STE) and PBLFT exchange (PFTE). Global air chemistry models include LNOx, but in very crude fashion, with the frequency and distribution of lightning being based on modeled cloud parameters (hence large uncertainty), lightning energetics being assumed to be constant for all flashes (literature value, while in reality there is at least a two-orders of magnitude variability from flash-to-flash), and the production of NOx in the surrounding heated air, per Joule of heating, being assumed to be constant also (literature value, while in fact it is a non-linear function of the dissipated heat and local air density, p). This situation is commonly blamed on paucity of pertinent observational data, but for the USA, there is now a wealth of surface- and satellite-based data of lightning available to permit much improved observation-based estimation of LNOx emissions. In the FT, such NOx has a long residence time, and also the ozone production efficiency from NOx there is considerably higher than in the PBL. It is, therefore, of critical importance in FT chemistry. This paper will describe the approach and data products of an ongoing NSSTC project aimed at a much-improved quantification of not only LNOx production on the scale of continental USA based on local and regional lightning observations, but also of intercontinental transport, STE and PFTE, all in upgraded simulations of tropospheric transport and chemistry. In our approach for LNOx, (a) we utilize continuous observed lightning information from the NLDN ground network and from satellite imagers (OTD and LIS) to quantify lightning frequency and distribution at the spatial-temporal scales of models such as CMAQ; (b) we develop new methodologies to quantify flash-specific lightning energy dissipation as heat (epsilon) using data from the research-grade lightning measurement facility at NASA-KSC, and to parameterize epsilon based on regional lightning monitoring data (ground- and satellite-based); and, (c) we develop a new parameterization of NOx production as a function of epsilon and rho. Based on such observation-based information, we are working to develop a gridded, episodic LNOx emissions inventory for the USA for use in models like CMAQ. We are also developing approaches for global(MOZART)- regional(CMAQ) chemistry coupling to improve intercontinental transport and STE. Finally, we are developing new methodologies for assimilation of satellite-observed (GOES) clouds into meteorological modeling (MM5), to improve PFTE and to optimize co-location of cloud convection and observed lightning. We will incorporate these improvements in CMAQ simulations over the USA to better understand FT processes and chemistry, and its impact on ground-level ozone.

International Aerospace and Ground Conference on Lightning and Static Electricity, 10th, and Congres International Aeronautique, 17th, Paris, France, June 10-13, 1985, Proceedings

NASA Astrophysics Data System (ADS)

1985-12-01

The conference presents papers on statistical data and standards, coupling and indirect effects, meteorology and thunderstorm studies, lightning simulators, fuel ignition hazards, the phenomenology and characterization of lightning, susceptibility and protection of avionics, ground systems protection, lightning locators, aircraft systems protection, structures and materials, electrostatics, and spacecraft protection against static electricity. Particular attention is given to a comparison of published HEMP and natural lightning on the surface of an aircraft, electromagnetic interaction of external impulse fields with aircraft, of thunderstorm currents and lightning charges at the NASA Kennedy Space Center, the design of a fast risetime lightning generator, lightning simulation tests in FAA CV-580 lightning research aircraft, and the energy requirements of an aircraft triggered discharge. Papers are also presented on aircraft lightning attachment at low altitudes, a new form of transient suppressor, a proving ground for lightning research, and a spacecraft materials test in a continuous, broad energy-spectrum electron beam.

Investigations in thunderstorm energetics using satellite instrumentation and Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Brunner, K. N.; Bitzer, P. M.

2017-12-01

The electrical energy dissipated by lightning is a fundamental question in lightning physics and may be used in severe weather applications. However, the electrical energy, flash area/extent and spectral energy density (radiance) are all influenced by the geometry of the lightning channel. We present details of a Monte Carlo based model simulating the optical emission from lightning and compare with observations. Using time-of-arrival techniques and the electric field change measurements from the Huntsville Alabama Marx Meter Array (HAMMA), the 4D lightning channel is reconstructed. The located sources and lightning channel emit optical emission, calibrated by the ground based electric field, that scatters until absorbed or a cloud boundary is reached within the model. At cloud top, the simulation is gridded as LIS pixels (events) and contiguous events (groups). The radiance is related via the LIS calibration and the estimated lightning electrical energy is calculated at the LIS/GLM time resolution. Previous Monte Carlo simulations have relied on a simplified lightning channel and scattering medium. This work considers the cloud a stratified medium of graupel/ice and inhomogeneous at flash scale. The impact of cloud inhomogeneity on the scattered optical emission at cloud top and at the time resolution of LIS and GLM are also considered. The simulation results and energy metrics provide an estimation of the electrical energy using GLM and LIS on the International Space Station (ISS-LIS).

A Probabilistic, Facility-Centric Approach to Lightning Strike Location

NASA Technical Reports Server (NTRS)

Huddleston, Lisa L.; Roeder, William p.; Merceret, Francis J.

2012-01-01

A new probabilistic facility-centric approach to lightning strike location has been developed. This process uses the bivariate Gaussian distribution of probability density provided by the current lightning location error ellipse for the most likely location of a lightning stroke and integrates it to determine the probability that the stroke is inside any specified radius of any location, even if that location is not centered on or even with the location error ellipse. This technique is adapted from a method of calculating the probability of debris collisionith spacecraft. Such a technique is important in spaceport processing activities because it allows engineers to quantify the risk of induced current damage to critical electronics due to nearby lightning strokes. This technique was tested extensively and is now in use by space launch organizations at Kennedy Space Center and Cape Canaveral Air Force Station. Future applications could include forensic meteorology.

Time domain simulations of preliminary breakdown pulses in natural lightning.

PubMed

Carlson, B E; Liang, C; Bitzer, P; Christian, H

2015-06-16

Lightning discharge is a complicated process with relevant physical scales spanning many orders of magnitude. In an effort to understand the electrodynamics of lightning and connect physical properties of the channel to observed behavior, we construct a simulation of charge and current flow on a narrow conducting channel embedded in three-dimensional space with the time domain electric field integral equation, the method of moments, and the thin-wire approximation. The method includes approximate treatment of resistance evolution due to lightning channel heating and the corona sheath of charge surrounding the lightning channel. Focusing our attention on preliminary breakdown in natural lightning by simulating stepwise channel extension with a simplified geometry, our simulation reproduces the broad features observed in data collected with the Huntsville Alabama Marx Meter Array. Some deviations in pulse shape details are evident, suggesting future work focusing on the detailed properties of the stepping mechanism. Preliminary breakdown pulses can be reproduced by simulated channel extension Channel heating and corona sheath formation are crucial to proper pulse shape Extension processes and channel orientation significantly affect observations.

Time domain simulations of preliminary breakdown pulses in natural lightning

PubMed Central

Carlson, B E; Liang, C; Bitzer, P; Christian, H

2015-01-01

Lightning discharge is a complicated process with relevant physical scales spanning many orders of magnitude. In an effort to understand the electrodynamics of lightning and connect physical properties of the channel to observed behavior, we construct a simulation of charge and current flow on a narrow conducting channel embedded in three-dimensional space with the time domain electric field integral equation, the method of moments, and the thin-wire approximation. The method includes approximate treatment of resistance evolution due to lightning channel heating and the corona sheath of charge surrounding the lightning channel. Focusing our attention on preliminary breakdown in natural lightning by simulating stepwise channel extension with a simplified geometry, our simulation reproduces the broad features observed in data collected with the Huntsville Alabama Marx Meter Array. Some deviations in pulse shape details are evident, suggesting future work focusing on the detailed properties of the stepping mechanism. Key Points Preliminary breakdown pulses can be reproduced by simulated channel extension Channel heating and corona sheath formation are crucial to proper pulse shape Extension processes and channel orientation significantly affect observations PMID:26664815

An Intrinsic Fiber-Optic Sensor for Structure Lightning Current Measurement

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.; Mata, Carlos T.; Mata, Angel. G.; Snyder, Gary P.

2014-01-01

An intrinsic optical-fiber sensor based on Faraday Effect is developed that is highly suitable for measuring lightning current on aircraft, towers and complex structures. Originally developed specifically for aircraft installations, it is light-weight, non-conducting, structure conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can measure total current down to DC. When used on lightning towers, the sensor can help validate other sensors and lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. A broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with a 60 dB dynamic range. Two systems were built that are similar in design but with slightly different sensitivities. The 1310nm laser system can measure 300 A - 300 kA, and has a 15m long sensing fiber. It was used in laboratory testing, including measuring current on an aluminum structure simulating an aircraft fuselage or a lightning tower. High current capabilities were demonstrated up to 200 kA at a lightning test facility. The 1550nm laser system can measure 400 A - 400 kA and has a 25m fiber length. Used in field measurements, excellent results were achieved in the summer of 2012 measuring rocket-triggered lightning at the International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida. In both systems increased sensitivity can be achieved with multiple fiber loops. The fiber optic sensor provides many unique capabilities not currently possible with traditional sensors. It represents an important new tool for lightning current measurement where low weight, complex shapes, large structure dimension, large current, and low frequency capabilities are important considerations.

Lightning Effects in the Payload Changeout Room

NASA Technical Reports Server (NTRS)

Thomas, Garland L.; Fisher, Franklin A.; Collier, Richard S.; Medelius, Pedro J.

1997-01-01

Analytical and empirical studies have been performed to provide better understanding of the electromagnetic environment inside the Payload Changeout Room and Orbiter payload bay resulting from lightning strikes to the launch pad lightning protection system. The analytical studies consisted of physical and mathematical modeling of the pad structure and the Payload Changeout Room. Empirical testing was performed using a lightning simulator to simulate controlled (8 kA) lightning strikes to the catenary wire lightning protection system. In addition to the analyses and testing listed above, an analysis of the configuration with the vehicle present was conducted, in lieu of testing, by the Finite Difference, Time Domain method.

Simulating Damage Due to a Lightning Strike Event: Effects of Temperature Dependent Properties on Interlaminar Damage

NASA Technical Reports Server (NTRS)

Ghezeljeh, Paria Naghipour; Pineda, Evan Jorge

2014-01-01

A multidirectional, carbon fiber-epoxy, composite panel is subjected to a simulated lightning strike, within a finite element method framework, and the effect of material properties on the failure (delamination) response is investigated through a detailed numerical study. The numerical model of the composite panel consists of individual homogenized plies with user-defined, cohesive interface elements between them. Lightning strikes are simulated as an assumed combination of excessive heat and high pressure loadings. It is observed that the initiation and propagation of lightning-induced delamination is a significant function of the temperature dependency of interfacial fracture toughness. This dependency must be defined properly in order to achieve reliable predictions of the present lightning-induced delamination in the composite panel.

Indirect Lightning Safety Assessment Methodology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ong, M M; Perkins, M P; Brown, C G

2009-04-24

Lightning is a safety hazard for high-explosives (HE) and their detonators. In the However, the current flowing from the strike point through the rebar of the building The methodology for estimating the risk from indirect lighting effects will be presented. It has two parts: a method to determine the likelihood of a detonation given a lightning strike, and an approach for estimating the likelihood of a strike. The results of these two parts produce an overall probability of a detonation. The probability calculations are complex for five reasons: (1) lightning strikes are stochastic and relatively rare, (2) the quality ofmore » the Faraday cage varies from one facility to the next, (3) RF coupling is inherently a complex subject, (4) performance data for abnormally stressed detonators is scarce, and (5) the arc plasma physics is not well understood. Therefore, a rigorous mathematical analysis would be too complex. Instead, our methodology takes a more practical approach combining rigorous mathematical calculations where possible with empirical data when necessary. Where there is uncertainty, we compensate with conservative approximations. The goal is to determine a conservative estimate of the odds of a detonation. In Section 2, the methodology will be explained. This report will discuss topics at a high-level. The reasons for selecting an approach will be justified. For those interested in technical details, references will be provided. In Section 3, a simple hypothetical example will be given to reinforce the concepts. While the methodology will touch on all the items shown in Figure 1, the focus of this report is the indirect effect, i.e., determining the odds of a detonation from given EM fields. Professor Martin Uman from the University of Florida has been characterizing and defining extreme lightning strikes. Using Professor Uman's research, Dr. Kimball Merewether at Sandia National Laboratory in Albuquerque calculated the EM fields inside a Faraday-cage type facility, when the facility is struck by lightning. In the following examples we will use Dr. Merewether's calculations from a poor quality Faraday cage as the input for the RF coupling analysis. coupling of radio frequency (RF) energy to explosive components is an indirect effect of currents [1]. If HE is adequately separated from the walls of the facility that is struck by disassembled have been turned into Faraday-cage structures to protect against lightning is initiation of the HE. last couple of decades, DOE facilities where HE is manufactured, assembled, stored or lightning. The most sensitive component is typically a detonator, and the safety concern lightning, electrons discharged from the clouds should not reach the HE components. radio receiver, the metal cable of a detonator can extract energy from the EM fields. This to the earth will create electromagnetic (EM) fields in the facility. Like an antenna in a« less

Electromagnetic sensors for general lightning application

NASA Technical Reports Server (NTRS)

Baum, C. E.; Breen, E. L.; Onell, J. P.; Moore, C. B.; Sower, G. D.

1980-01-01

Electromagnetic sensors for general lightning applications in measuring environment are discussed as well as system response to the environment. This includes electric and magnetic fields, surface current and charge densities, and currents on conductors. Many EMP sensors are directly applicable to lightning measurements, but there are some special cases of lightning measurements involving direct strikes which require special design considerations for the sensors. The sensors and instrumentation used by NMIMT in collecting data on lightning at South Baldy peak in central New Mexico during the 1978 and 1979 lightning seasons are also discussed. The Langmuir Laboratory facilities and details of the underground shielded instrumentation room and recording equipment are presented.

Designs for surge immunity in critical electronic facilities

NASA Technical Reports Server (NTRS)

Roberts, Edward F., Jr.

1991-01-01

In recent years, Federal Aviation Administration (FAA) embarked on a program replacing older tube type electronic equipment with newer solid state equipment. This replacement program dramatically increased the susceptibility of the FAA's facilities to lightning related damages. The proposal is presented of techniques which may be employed to lessen the susceptibility of new FAA electronic facility designs to failures resulting from lightning related surges and transients as well as direct strikes. The general concept espoused is one of a consistent system approach employing both perimeter and internal protection. It compares the technique presently employed to reduce electronic noise with other techniques which reduce noise while lowering susceptibility to lightning related damage. It is anticipated that these techniques will be employed in the design of an Air Traffic Control Tower in a high isokeraunic area. This facility would be subjected to rigorous monitoring over a multi-year period to provide quantitative data hopefully supporting the advantage of this design.

Use of High-resolution WRF Simulations to Forecast Lightning Threat

NASA Technical Reports Server (NTRS)

McCaul, William E.; LaCasse, K.; Goodman, S. J.

2006-01-01

Recent observational studies have confirmed the existence of a robust statistical relationship between lightning flash rates and the amount of large precipitating ice hydrometeors in storms. This relationship is exploited, in conjunction with the capabilities of recent forecast models such as WRF, to forecast the threat of lightning from convective storms using the output fields from the model forecasts. The simulated vertical flux of graupel at -15C is used in this study as a proxy for charge separation processes and their associated lightning risk. Six-h simulations are conducted for a number of case studies for which three-dimensional lightning validation data from the North Alabama Lightning Mapping Array are available. Experiments indicate that initialization of the WRF model on a 2 km grid using Eta boundary conditions, Doppler radar radial velocity and reflectivity fields, and METAR and ACARS data yield the most realistic simulations. An array of subjective and objective statistical metrics are employed to document the utility of the WRF forecasts. The simulation results are also compared to other more traditional means of forecasting convective storms, such as those based on inspection of the convective available potential energy field.

Measurements of induced voltages and currents in a distribution power line and associated atmospheric parameters

NASA Technical Reports Server (NTRS)

Santiago-Perez, Julio

1988-01-01

The frequency and intensity of thunderstorms around the Kennedy Space Center (KSC) has affected scheduled launch, landing, and other ground operations for many years. In order to protect against and provide safe working facilities, KSC has performed and hosted several studies on lightning phenomena. For the reasons mentioned above, KSC has established the Atmospheric Science Field Laboratory (ASFL). At these facilities KSC launches wire-towing rockets into thunderstorms to trigger natural lightning to the launch site. A program named Rocket Triggered Lightning Program (RTLP) is being conducted at the ASFL. This report calls for two of the experiments conducted in the summer 1988 Rocket Triggered Lightning Program. One experiment suspended an electric field mill over the launching areas from a balloon about 500 meters high to measure the space charges over the launching area. The other was to connect a waveform recorder to a nearby distribution power line to record currents and voltages wave forms induced by natural and triggered lightning.

Measurements of induced voltages and currents in a distribution power line and associated atmospheric parameters

NASA Astrophysics Data System (ADS)

Santiago-Perez, Julio

1988-10-01

The frequency and intensity of thunderstorms around the Kennedy Space Center (KSC) has affected scheduled launch, landing, and other ground operations for many years. In order to protect against and provide safe working facilities, KSC has performed and hosted several studies on lightning phenomena. For the reasons mentioned above, KSC has established the Atmospheric Science Field Laboratory (ASFL). At these facilities KSC launches wire-towing rockets into thunderstorms to trigger natural lightning to the launch site. A program named Rocket Triggered Lightning Program (RTLP) is being conducted at the ASFL. This report calls for two of the experiments conducted in the summer 1988 Rocket Triggered Lightning Program. One experiment suspended an electric field mill over the launching areas from a balloon about 500 meters high to measure the space charges over the launching area. The other was to connect a waveform recorder to a nearby distribution power line to record currents and voltages wave forms induced by natural and triggered lightning.

Effects of lightning NOx production during the 21 July European Lightning Nitrogen Oxides Project storm studied with a three-dimensional cloud-scale chemical transport model

NASA Astrophysics Data System (ADS)

Ott, Lesley E.; Pickering, Kenneth E.; Stenchikov, Georgiy L.; Huntrieser, Heidi; Schumann, Ulrich

2007-03-01

The 21 July 1998 thunderstorm observed during the European Lightning Nitrogen Oxides Project (EULINOX) project was simulated using the three-dimensional Goddard Cumulus Ensemble (GCE) model. The simulation successfully reproduced a number of observed storm features including the splitting of the original cell into a southern cell which developed supercell characteristics and a northern cell which became multicellular. Output from the GCE simulation was used to drive an offline cloud-scale chemical transport model which calculates tracer transport and includes a parameterization of lightning NOx production which uses observed flash rates as input. Estimates of lightning NOx production were deduced by assuming various values of production per intracloud and production per cloud-to-ground flash and comparing the results with in-cloud aircraft observations. The assumption that both types of flashes produce 360 moles of NO per flash on average compared most favorably with column mass and probability distribution functions calculated from observations. This assumed production per flash corresponds to a global annual lightning NOx source of 7 Tg N yr-1. Chemical reactions were included in the model to evaluate the impact of lightning NOx on ozone. During the storm, the inclusion of lightning NOx in the model results in a small loss of ozone (on average less than 4 ppbv) at all model levels. Simulations of the chemical environment in the 24 hours following the storm show on average a small increase in the net production of ozone at most levels resulting from lightning NOx, maximizing at approximately 5 ppbv day-1 at 5.5 km. Between 8 and 10.5 km, lightning NOx causes decreased net ozone production.

Evolution simulation of lightning discharge based on a magnetohydrodynamics method

NASA Astrophysics Data System (ADS)

Fusheng, WANG; Xiangteng, MA; Han, CHEN; Yao, ZHANG

2018-07-01

In order to solve the load problem for aircraft lightning strikes, lightning channel evolution is simulated under the key physical parameters for aircraft lightning current component C. A numerical model of the discharge channel is established, based on magnetohydrodynamics (MHD) and performed by FLUENT software. With the aid of user-defined functions and a user-defined scalar, the Lorentz force, Joule heating and material parameters of an air thermal plasma are added. A three-dimensional lightning arc channel is simulated and the arc evolution in space is obtained. The results show that the temperature distribution of the lightning channel is symmetrical and that the hottest region occurs at the center of the lightning channel. The distributions of potential and current density are obtained, showing that the difference in electric potential or energy between two points tends to make the arc channel develop downwards. The arc channel comes into expansion on the anode surface due to stagnation of the thermal plasma and there exists impingement on the copper plate when the arc channel comes into contact with the anode plate.

Oceanic Lightning versus Continental Lightning: VLF Peak Current Discrepancies

NASA Astrophysics Data System (ADS)

Dupree, N. A., Jr.; Moore, R. C.

2015-12-01

Recent analysis of the Vaisala global lightning data set GLD360 suggests that oceanic lightning tends to exhibit larger peak currents than continental lightning (lightning occurring over land). The GLD360 peak current measurement is derived from distant measurements of the electromagnetic fields emanated during the lightning flash. Because the GLD360 peak current measurement is a derived quantity, it is not clear whether the actual peak currents of oceanic lightning tend to be larger, or whether the resulting electromagnetic field strengths tend to be larger. In this paper, we present simulations of VLF signal propagation in the Earth-ionosphere waveguide to demonstrate that the peak field values for oceanic lightning can be significantly stronger than for continental lightning. Modeling simulations are performed using the Long Wave Propagation Capability (LWPC) code to directly evaluate the effect of ground conductivity on VLF signal propagation in the 5-15 kHz band. LWPC is an inherently narrowband propagation code that has been modified to predict the broadband response of the Earth-Ionosphere waveguide to an impulsive lightning flash while preserving the ability of LWPC to account for an inhomogeneous waveguide. Furthermore, we evaluate the effect of return stroke speed on these results.

High current lightning test of space shuttle external tank lightning protection system

NASA Technical Reports Server (NTRS)

Mumme, E.; Anderson, A.; Schulte, E. H.

1977-01-01

During lift-off, the shuttle launch vehicle (external tank, solid rocket booster and orbiter) may be subjected to a lightning strike. Tests of a proposed lightning protection method for the external tank and development materials which were subjected to simulated lightning strikes are described. Results show that certain of the high resistant paint strips performed remarkably well in diverting the 50 kA lightning strikes.

Lightning Forcing in Global Fire Models: The Importance of Temporal Resolution

NASA Astrophysics Data System (ADS)

Felsberg, A.; Kloster, S.; Wilkenskjeld, S.; Krause, A.; Lasslop, G.

2018-01-01

In global fire models, lightning is typically prescribed from observational data with monthly mean temporal resolution while meteorological forcings, such as precipitation or temperature, are prescribed in a daily resolution. In this study, we investigate the importance of the temporal resolution of the lightning forcing for the simulation of burned area by varying from daily to monthly and annual mean forcing. For this, we utilize the vegetation fire model JSBACH-SPITFIRE to simulate burned area, forced with meteorological and lightning data derived from the general circulation model ECHAM6. On a global scale, differences in burned area caused by lightning forcing applied in coarser temporal resolution stay below 0.55% compared to the use of daily mean forcing. Regionally, however, differences reach up to 100%, depending on the region and season. Monthly averaged lightning forcing as well as the monthly lightning climatology cause differences through an interaction between lightning ignitions and fire prone weather conditions, accounted for by the fire danger index. This interaction leads to decreased burned area in the boreal zone and increased burned area in the Tropics and Subtropics under the coarser temporal resolution. The exclusion of interannual variability, when forced with the lightning climatology, has only a minor impact on the simulated burned area. Annually averaged lightning forcing causes differences as a direct result of the eliminated seasonal characteristics of lightning. Burned area is decreased in summer and increased in winter where fuel is available. Regions with little seasonality, such as the Tropics and Subtropics, experience an increase in burned area.

Improving Lightning and Precipitation Prediction of Severe Convection Using Lightning Data Assimilation With NCAR WRF-RTFDDA

NASA Astrophysics Data System (ADS)

Wang, Haoliang; Liu, Yubao; Cheng, William Y. Y.; Zhao, Tianliang; Xu, Mei; Liu, Yuewei; Shen, Si; Calhoun, Kristin M.; Fierro, Alexandre O.

2017-11-01

In this study, a lightning data assimilation (LDA) scheme was developed and implemented in the National Center for Atmospheric Research Weather Research and Forecasting-Real-Time Four-Dimensional Data Assimilation system. In this LDA method, graupel mixing ratio (qg) is retrieved from observed total lightning. To retrieve qg on model grid boxes, column-integrated graupel mass is first calculated using an observation-based linear formula between graupel mass and total lightning rate. Then the graupel mass is distributed vertically according to the empirical qg vertical profiles constructed from model simulations. Finally, a horizontal spread method is utilized to consider the existence of graupel in the adjacent regions of the lightning initiation locations. Based on the retrieved qg fields, latent heat is adjusted to account for the latent heat releases associated with the formation of the retrieved graupel and to promote convection at the observed lightning locations, which is conceptually similar to the method developed by Fierro et al. Three severe convection cases were studied to evaluate the LDA scheme for short-term (0-6 h) lightning and precipitation forecasts. The simulation results demonstrated that the LDA was effective in improving the short-term lightning and precipitation forecasts by improving the model simulation of the qg fields, updrafts, cold pool, and front locations. The improvements were most notable in the first 2 h, indicating a highly desired benefit of the LDA in lightning and convective precipitation nowcasting (0-2 h) applications.

A WRF-Chem Analysis of Flash Rates, Lightning-NOx Production and Subsequent Trace Gas Chemistry of the 29-30 May 2012 Convective Event in Oklahoma During DC3

NASA Technical Reports Server (NTRS)

Cummings, Kristin A.; Pickering, Kenneth; Barth, Mary; Weinheimer, A.; Bela, M.; Li, Y; Allen, D.; Bruning, E.; MacGorman, D.; Rutledge, S.;

An Approach to the Lightning Overvoltage Protection of Medium Voltage Lines in Severe Lightning Areas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omidiora, M. A.; Lehtonen, M.

2008-05-08

This paper deals with the effect of shield wires on lightning overvoltage reduction and the energy relief of MOV (Metal Oxide Varistor) arresters from direct strokes to distribution lines. The subject of discussion is the enhancement of lightning protection in Finnish distribution networks where lightning is most severe. The true index of lightning severity in these areas is based on the ground flash densities and return stroke data collected from the Finnish meteorological institute. The presented test case is the IEEE 34-node test feeder injected with multiple lightning strokes and simulated with the Alternative Transients Program/Electromagnetic Transients program (ATP/EMTP). Themore » response of the distribution line to lightning strokes was modeled with three different cases: no protection, protection with surge arresters and protection with a combination of shield wire and arresters. Simulations were made to compare the resulting overvoltages on the line for all the analyzed cases.« less

COMSOL based Simulation on the Effect of Electric Field changes due to Lightning on Ground

NASA Astrophysics Data System (ADS)

Premlet, B.; Joby, N. E.; Sabu, S.

2017-12-01

The phenomenon of lightning is accompanied by localised changes in atmospheric electric fields. In cloud-to-ground strike locations, changes in atmospheric electric fields can even be observed at the ground a few minutes prior to a strike. A lot of research has been done already on the electrostatic changes prior to lightning in the region above ground. Through this work, we investigate into the effects of lightning electric fields on/under ground with the aid of simulations done in COMSOL Multiphysics. Horizontal and vertical profiles of voltage gradient, electric field, polarisation etc. are investigated. Simulation experiments were conducted using a general model of lightning electric fields formed using data recorded by the Electric Field Mills(EFMs) from three diverse parts of the world- Kennedy Space Centre (KSC),Florida (Using GHRC datasets),Sonnblick Observatory, Austria and National Centre for Earth Science Studies Trivandrum (NCESS),India. COMSOL models of the global electric circuit were developed using Sandstone as the base model for ground. Similar works in literature have only dealt with lightning electric fields above the ground. This work is the first step towards a high-level simulation on the effects of atmospheric electric field on/below ground. The results of this simulation work can aid lightning forecasting and preparedness by opening new doors for voltage based prediction methods at ground. It is also a tool to understand phenomena such as fulgurites, corona effect etc. It also helps in the design of buried cables and improved grounding systems. This work can also be a first step towards understanding localised potential variations at the ground during lightning.

Direct-strike lightning photographs, swept-flash attachment patterns, and flight conditions for storm hazards 1982

NASA Technical Reports Server (NTRS)

Zaepfel, K. P.; Fisher, B. D.; Ott, M. S.

1985-01-01

As part of the NASA Langley Research Center Storm Hazards Program, 241 thunderstorm penetrations were made in 1982 with an F-106B airplane in order to record direct-strike lightning data and the associated flight conditions. During these penetrations, the airplane received 156 direct lightning strikes; in addition, lightning transient data were recorded from 26 nearby lightning flashes. The tests were conducted within 150 nautical miles of Hampton, Virginia, assisted by ground-based weather-radar guidance from the NASA Wallops Flight Facility. The photographs of the lightning attachments taken from two onboard 16-mm color movie cameras and the associated strike attachment patterns are presented. A table of the flight conditions recorded at the time of each lightning event, and a table in which the data are cross-referenced with the previously published lightning electromagnetic waveform data are included.

The Effects of Lightning NO(x) Production during the July 21 EULINOX Storm studied with a 3-D Cloud-scale Chemical Transport Model

NASA Technical Reports Server (NTRS)

Ott, Lesley E.; Pickering, Kenneth E.; Stenchikov, Georgiy L.; Huntrieser, Heidi; Schumann, Ulrich

2006-01-01

The July 21,1998 thunderstonn observed during the European Lightning Nitrogen Oxides Project (EULINOX) project was simulated using the three-dimensional Goddard Cumulus Ensemble (GCE) model. The simulation successfully reproduced a number of observed storm features including the splitting of the original cell into a southern cell which developed supercell characteristics, and a northern cell which became multicellular. Output from the GCE simulation was used to drive an offline cloud-scale chemical transport model which calculates tracer transport and includes a parameterization of lightning NO(x) production which uses observed flash rates as input. Estimates of lightning NO(x) production were deduced by assuming various values of production per intracloud and production per cloud-to-ground flash and comparing the results with in-cloud aircraft observations. The assumption that both types of flashes produce 360 moles of NO per flash on average compared most favorably with column mass and probability distribution functions calculated from observations. This assumed production per flash corresponds to a global annual lightning NOx source of 7 Tg N per yr. Chemical reactions were included in the model to evaluate the impact of lightning NO(x), on ozone. During the storm, the inclusion of lightning NOx in the model results in a small loss of ozone (on average less than 4 ppbv) at all model levels. Simulations of the chemical environment in the 24 hours following the storm show on average a small increase in the net production of ozone at most levels resulting from lightning NO(x), maximizing at approximately 5 ppbv per day at 5.5 km. Between 8 and 10.5 km, lightning NO(x) causes decreased net ozone production.

High-Resolution WRF Forecasts of Lightning Threat

NASA Technical Reports Server (NTRS)

Goodman, S. J.; McCaul, E. W., Jr.; LaCasse, K.

2007-01-01

Tropical Rainfall Measuring Mission (TRMM)lightning and precipitation observations have confirmed the existence of a robust relationship between lightning flash rates and the amount of large precipitating ice hydrometeors in storms. This relationship is exploited, in conjunction with the capabilities of the Weather Research and Forecast (WRF) model, to forecast the threat of lightning from convective storms using the output fields from the model forecasts. The simulated vertical flux of graupel at -15C is used in this study as a proxy for charge separation processes and their associated lightning risk. Initial experiments using 6-h simulations are conducted for a number of case studies for which three-dimensional lightning validation data from the North Alabama Lightning Mapping Array are available. The WRF has been initialized on a 2 km grid using Eta boundary conditions, Doppler radar radial velocity and reflectivity fields, and METAR and ACARS data. An array of subjective and objective statistical metrics is employed to document the utility of the WRF forecasts. The simulation results are also compared to other more traditional means of forecasting convective storms, such as those based on inspection of the convective available potential energy field.

Chemical Safety Alert: Lightning Hazard to Facilities Handling Flammable Substances

EPA Pesticide Factsheets

Raises awareness about lightning strikes, which cause more death/injury and damage than all other environmental elements combined, so industry can take proper precautions to protect equipment and storage or process vessels containing flammable materials.

The Deep Space Gateway Lightning Mapper (DLM) - Monitoring Global Change and Thunderstorm Processes Through Observations of Earth's High-Latitude Lightning from Cis-Lunar Orbit

NASA Technical Reports Server (NTRS)

Lang, Timothy; Blakeslee, R. J.; Cecil, D. J.; Christian, H. J.; Gatlin, P. N.; Goodman, S. J.; Koshak, W. J.; Petersen, W. A.; Quick, M.; Schultz, C. J.;

Lightning Damage of Carbon Fiber/Epoxy Laminates with Interlayers Modified by Nickel-Coated Multi-Walled Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Dong, Qi; Wan, Guoshun; Xu, Yongzheng; Guo, Yunli; Du, Tianxiang; Yi, Xiaosu; Jia, Yuxi

2017-12-01

The numerical model of carbon fiber reinforced polymer (CFRP) laminates with electrically modified interlayers subjected to lightning strike is constructed through finite element simulation, in which both intra-laminar and inter-laminar lightning damages are considered by means of coupled electrical-thermal-pyrolytic analysis method. Then the lightning damage extents including the damage volume and maximum damage depth are investigated. The results reveal that the simulated lightning damages could be qualitatively compared to the experimental counterparts of CFRP laminates with interlayers modified by nickel-coated multi-walled carbon nanotubes (Ni-MWCNTs). With higher electrical conductivity of modified interlayer and more amount of modified interlayers, both damage volume and maximum damage depth are reduced. This work provides an effective guidance to the anti-lightning optimization of CFRP laminates.

Assessment and forecasting of lightning potential and its effect on launch operations at Cape Canaveral Air Force Station and John F. Kennedy Space Center

NASA Technical Reports Server (NTRS)

Weems, J.; Wyse, N.; Madura, J.; Secrist, M.; Pinder, C.

1991-01-01

Lightning plays a pivotal role in the operation decision process for space and ballistic launches at Cape Canaveral Air Force Station and Kennedy Space Center. Lightning forecasts are the responsibility of Detachment 11, 4th Weather Wing's Cape Canaveral Forecast Facility. These forecasts are important to daily ground processing as well as launch countdown decisions. The methodology and equipment used to forecast lightning are discussed. Impact on a recent mission is summarized.

Lightning vulnerability of fiber-optic cables.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez, Leonard E.; Caldwell, Michele

2008-06-01

One reason to use optical fibers to transmit data is for isolation from unintended electrical energy. Using fiber optics in an application where the fiber cable/system penetrates the aperture of a grounded enclosure serves two purposes: first, it allows for control signals to be transmitted where they are required, and second, the insulating properties of the fiber system help to electrically isolate the fiber terminations on the inside of the grounded enclosure. A fundamental question is whether fiber optic cables can allow electrical energy to pass through a grounded enclosure, with a lightning strike representing an extreme but very importantmore » case. A DC test bed capable of producing voltages up to 200 kV was used to characterize electrical properties of a variety of fiber optic cable samples. Leakage current in the samples were measured with a micro-Ammeter. In addition to the leakage current measurements, samples were also tested to DC voltage breakdown. After the fiber optic cables samples were tested with DC methods, they were tested under representative lightning conditions at the Sandia Lightning Simulator (SLS). Simulated lightning currents of 30 kA and 200 kA were selected for this test series. This paper documents measurement methods and test results for DC high voltage and simulated lightning tests performed at the Sandia Lightning Simulator on fiber optic cables. The tests performed at the SLS evaluated whether electrical energy can be conducted inside or along the surface of a fiber optic cable into a grounded enclosure under representative lightning conditions.« less

Analytic Perturbation Method for Estimating Ground Flash Fraction from Satellite Lightning Observations

NASA Technical Reports Server (NTRS)

Koshak, William; Solakiewicz, Richard

2013-01-01

An analytic perturbation method is introduced for estimating the lightning ground flash fraction in a set of N lightning flashes observed by a satellite lightning mapper. The value of N is large, typically in the thousands, and the observations consist of the maximum optical group area produced by each flash. The method is tested using simulated observations that are based on Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) data. National Lightning Detection NetworkTM (NLDN) data is used to determine the flash-type (ground or cloud) of the satellite-observed flashes, and provides the ground flash fraction truth for the simulation runs. It is found that the mean ground flash fraction retrieval errors are below 0.04 across the full range 0-1 under certain simulation conditions. In general, it is demonstrated that the retrieval errors depend on many factors (i.e., the number, N, of satellite observations, the magnitude of random and systematic measurement errors, and the number of samples used to form certain climate distributions employed in the model).

Simulating Realistic Test Data for the European Lightning Imager on MTG using Data from Seviri, TRMM-LIS and ISS-LIS

NASA Astrophysics Data System (ADS)

Finke, U.; Blakeslee, R. J.; Mach, D. M.

2017-12-01

The next generation of European geostationary weather observing satellites (MTG) will operate an optical lightning location instrument (LI) which will be very similar to the Global Lightning Mapper (GLM) on board of GOES-R. For the development and verification of the product processing algorithms realistic test data are necessary. This paper presents a method of test data generation on the basis of optical lightning data from the LIS instrument and cloud image data from the Seviri radiometer.The basis is the lightning data gathered during the 15 year LIS operation time, particularly the empirical distribution functions of the optical pulse size, duration and radiance as well as the inter-correlation of lightning in space and time. These allow for a realistically structured simulation of lightning test data. Due to its low orbit the instantaneous field of view of the LIS is limited and moving with time. For the generation of test data which cover the geostationary visible disk, the LIS data have to be extended. This is realized by 1. simulating random lightning pulses according to the established distribution functions of the lightning parameters and 2. using the cloud radiometer data of the Seviri instrument on board of the geostationary Meteosat second generation (MSG). Particularly, the cloud top height product (CTH) identifies convective storm clouds wherein the simulation places random lightning pulses. The LIS instrument was recently deployed on the International Space Station (ISS). The ISS orbit reaches higher latitudes, particularly Europe. The ISS-LIS data is analyzed for single observation days. Additionally, the statistical distribution of parameters such as radiance, footprint size, and space time correlation of the groups are compared against the long time statistics from TRMM-LIS.Optical lightning detection efficiency from space is affected by the solar radiation reflected from the clouds. This effect is changing with day and night areas across the field of view. For a realistic simulation of this cloud background radiance the Seviri visual channel VIS08 data is used.Additionally to the test data study, this paper gives a comparison of the MTG-LI to the GLM and discusses differences in instrument design, product definition and generation and the merging of data from both geostationary instruments.

Forecasting Lightning Threat using Cloud-resolving Model Simulations

NASA Technical Reports Server (NTRS)

McCaul, E. W., Jr.; Goodman, S. J.; LaCasse, K. M.; Cecil, D. J.

2009-01-01

As numerical forecasts capable of resolving individual convective clouds become more common, it is of interest to see if quantitative forecasts of lightning flash rate density are possible, based on fields computed by the numerical model. Previous observational research has shown robust relationships between observed lightning flash rates and inferred updraft and large precipitation ice fields in the mixed phase regions of storms, and that these relationships might allow simulated fields to serve as proxies for lightning flash rate density. It is shown in this paper that two simple proxy fields do indeed provide reasonable and cost-effective bases for creating time-evolving maps of predicted lightning flash rate density, judging from a series of diverse simulation case study events in North Alabama for which Lightning Mapping Array data provide ground truth. One method is based on the product of upward velocity and the mixing ratio of precipitating ice hydrometeors, modeled as graupel only, in the mixed phase region of storms at the -15\\dgc\\ level, while the second method is based on the vertically integrated amounts of ice hydrometeors in each model grid column. Each method can be calibrated by comparing domainwide statistics of the peak values of simulated flash rate proxy fields against domainwide peak total lightning flash rate density data from observations. Tests show that the first method is able to capture much of the temporal variability of the lightning threat, while the second method does a better job of depicting the areal coverage of the threat. A blended solution is designed to retain most of the temporal sensitivity of the first method, while adding the improved spatial coverage of the second. Weather Research and Forecast Model simulations of selected North Alabama cases show that this model can distinguish the general character and intensity of most convective events, and that the proposed methods show promise as a means of generating quantitatively realistic fields of lightning threat. However, because models tend to have more difficulty in correctly predicting the instantaneous placement of storms, forecasts of the detailed location of the lightning threat based on single simulations can be in error. Although these model shortcomings presently limit the precision of lightning threat forecasts from individual runs of current generation models, the techniques proposed herein should continue to be applicable as newer and more accurate physically-based model versions, physical parameterizations, initialization techniques and ensembles of cloud-allowing forecasts become available.

Use of Vertically Integrated Ice in WRF-Based Forecasts of Lightning Threat

NASA Technical Reports Server (NTRS)

McCaul, E. W., jr.; Goodman, S. J.

2008-01-01

Previously reported methods of forecasting lightning threat using fields of graupel flux from WRF simulations are extended to include the simulated field of vertically integrated ice within storms. Although the ice integral shows less temporal variability than graupel flux, it provides more areal coverage, and can thus be used to create a lightning forecast that better matches the areal coverage of the lightning threat found in observations of flash extent density. A blended lightning forecast threat can be constructed that retains much of the desirable temporal sensitivity of the graupel flux method, while also incorporating the coverage benefits of the ice integral method. The graupel flux and ice integral fields contributing to the blended forecast are calibrated against observed lightning flash origin density data, based on Lightning Mapping Array observations from a series of case studies chosen to cover a wide range of flash rate conditions. Linear curve fits that pass through the origin are found to be statistically robust for the calibration procedures.

Bioelectromagnetic effects of EMP: Preliminary findings

NASA Astrophysics Data System (ADS)

Aldrich, T. E.; Easterly, C. E.; Gailey, P. C.; Hamilton, C. B.

1988-06-01

Facilities to simulate electromagnetic pulses (EMPs) are used to test military equipment and electrical communications devices for resistance to the effects of an EMP caused by an upper-atmospheric nuclear detonation. The rapid rise time and high field strengths (0.1 to 50 kV/m) of an EMP distinguish it from other electromagnetic phenomena. Certain types of EMP simulators also expose facility operators and members of the public to electromagnetic fields of varying intensity as do other natural sources such as the fields produced near a lightning bolt. Limited biological effects data have been collected to assess the potential EMP health hazards to humans. Evidence from the available database does not establish that EMPs represent either an occupational or a public health hazard. A critique is presented of the EMP research published to date in order to explore its limitations and similarities with related outcome experience from other electromagnetic field research. Laboratory research and multiple years of observations on workers in existing EMP manufacturing and simulation facilities suggest that there are no acute or short-term health effects. The occupational exposure guideline for EMP is 100 kV/m, which is far in excess of usual exposures with EMP simulators.

Infrasound from lightning measured in Ivory Coast

NASA Astrophysics Data System (ADS)

Farges, T.; Millet, C.; Matoza, R. S.

2012-04-01

It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. More than two thirds (42) of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes, …). Some of the IMS stations are located where worldwide lightning detection networks (e.g. WWLLN) have a weak detection capability but lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. For example, Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within a range of distances from the infrasound station. Infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. The motion of the squall zone is very well measured inside this zone. Up to 25% of lightning flashes can be detected with this technique, giving better results locally than worldwide lightning detection networks. An IMS infrasound station has been installed in Ivory Coast for 9 years. The lightning rate of this region is 10-20 flashes/km2/year from space-based instrument OTD (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 4 years of data (2005-2009). For short lightning distances (less than 20 km), up to 60 % of lightning detected by WWLLN has been one-to-one correlated. Moreover, numerous infrasound events which have the infrasound from lightning signature could not be correlated when thunderstorms were close to the station. Statistical analyses of all correlated infrasound events show an exponential decrease of the infrasound amplitude with the distance of one order of magnitude per 50 km. These analyses show also that the relative position of lightning is important: the detection limit is higher when lightning occur at the East of the station than when they occur at the West. The dominant wind (the Easterlies) could be responsible of this dissymmetry. It also exists a high variability of detection efficiency with the seasons (better efficiency in fall than in spring). Finally, these statistics show clearly a structure inside the shadow zone (from 70 to 200 km away from the station). These results will be compared with intensive numerical simulations. The simulations are separated into two parts: the simulation of the near-field blast wave generated by a lightning and the simulation of the non-linear propagation of the shock front through a realistic atmosphere. By comparing our numerical results to recorded data over a full 1-year period, we aim to show that dominant features of statistics at the IMS station may be explained by the meteorological variability.

MSFC shuttle lightning research

NASA Technical Reports Server (NTRS)

Vaughan, Otha H., Jr.

1993-01-01

The shuttle mesoscale lightning experiment (MLE), flown on earlier shuttle flights, and most recently flown on the following space transportation systems (STS's), STS-31, -32, -35, -37, -38, -40, -41, and -48, has continued to focus on obtaining additional quantitative measurements of lightning characteristics and to create a data base for use in demonstrating observation simulations for future spaceborne lightning mapping systems. These flights are also providing design criteria data for the design of a proposed shuttle MLE-type lightning research instrument called mesoscale lightning observational sensors (MELOS), which are currently under development here at MSFC.

A stepped leader model for lightning including charge distribution in branched channels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Wei; Zhang, Li; Li, Qingmin, E-mail: lqmeee@ncepu.edu.cn

2014-09-14

The stepped leader process in negative cloud-to-ground lightning plays a vital role in lightning protection analysis. As lightning discharge usually presents significant branched or tortuous channels, the charge distribution along the branched channels and the stochastic feature of stepped leader propagation were investigated in this paper. The charge density along the leader channel and the charge in the leader tip for each lightning branch were approximated by introducing branch correlation coefficients. In combination with geometric characteristics of natural lightning discharge, a stochastic stepped leader propagation model was presented based on the fractal theory. By comparing simulation results with the statisticsmore » of natural lightning discharges, it was found that the fractal dimension of lightning trajectory in simulation was in the range of that observed in nature and the calculation results of electric field at ground level were in good agreement with the measurements of a negative flash, which shows the validity of this proposed model. Furthermore, a new equation to estimate the lightning striking distance to flat ground was suggested based on the present model. The striking distance obtained by this new equation is smaller than the value estimated by previous equations, which indicates that the traditional equations may somewhat overestimate the attractive effect of the ground.« less

Situational Lightning Climatologies for Central Florida, Phase 2, Part 3

NASA Technical Reports Server (NTRS)

Bauman, William H., III

2007-01-01

The threat of lightning is a daily concern during the warm season in Florida. The forecasters at the Spaceflight Meteorology Group (SMG) at Johnson Spaceflight Center in Houston, TX consider lightning in their landing forecasts for space shuttles at the Kennedy Space Center (KSC), FL Shuttle Landing Facility (SLF). The forecasters at the National Weather Service in Melbourne, FL (NWS MLB) do the same in their routine Terminal Aerodrome Forecasts (TAFs) for seven airports in the NWS MLB County Warning Area (CWA). The Applied Meteorology Unit created flow regime climatologies of lightning probability in the 5-, 10-, 20-, and 30-n mi circles surrounding the Shuttle Landing Facility (SLF) and all airports in the NWS MLB county warning area in 1-, 3-, and 6-hour increments. The results were presented in tabular and graphical format and incorporated into a web-based graphical user interface so forecasters could easily navigate through the data and to make the GUI usable in any web browser on computers with different operating systems.

WRF-Chem Simulations of Lightning-NOx Production and Transport in Oklahoma and Colorado Thunderstorms Observed During DC3

NASA Technical Reports Server (NTRS)

Cummings, Kristin A.; Pickering, Kenneth E.; Barth, M.; Bela, M.; Li, Y.; Allen, D.; Bruning, E.; MacGorman, D.; Rutledge, S.; Basarab, B.;

Lightning flash density versus altitude and storm structure from observations with UHF- and S-band radars

NASA Technical Reports Server (NTRS)

Mazur, V.; Gerlach, J. C.; Rust, W. D.

1984-01-01

The UHF-(70.5 cm wavelength) and S-band (10 cm wavelength) radar at NASA/Wallops Island Research Facility in Virginia, U.S.A. have been used to relate lightning activity with altitude and with the reflectivity structure of thunderstorms. Two centers of lightning flash density were found; one between 6 and 8 km altitude and another between 11 and 15 km. Previously announced in STAR as N83-31206

Lightning Protection System for HE Facilities at LLNL - Certification Template

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clancy, T J; Ong, M M; Brown, C G

2005-12-08

This document is meant as a template to assist in the development of your own lighting certification process. Aside from this introduction and the mock representative name of the building (Building A), this document is nearly identical to a lightning certification report issued by the Engineering Directorate at Lawrence Livermore National Laboratory. At the date of this release, we have certified over 70 HE processing and storage cells at our Site 300 facilities. In Chapters 1 and 2 respectively, we address the need and methods of lightning certification for HE processing and storage facilities at LLNL. We present the preferredmore » method of lightning protection in Chapter 3, as well as the likely building modifications that are needed to comply with this method. In Chapter 4, we present the threat assessment and resulting safe work areas within a cell. After certification, there may be changes to operations during a lightning alert, and this is discussed in Chapter 5. Chapter 6 lists the maintenance requirements for the continuation of lighting certification status. Appendices of this document are meant as an aid in developing your own certification process, and they include a bonding list, an inventory of measurement equipment, surge suppressors in use at LLNL, an Integrated Work and Safety form (IWS), and a template certification sign-off sheet. The lightning certification process involves more that what is spelled out in this document. The first steps involve considerable planning, the securing of funds, and management and explosives safety buy-in. Permits must be obtained, measurement equipment must be assembled and tested, and engineers and technicians must be trained in their use. Cursory building inspections are also recommended, and surge suppression for power systems must be addressed. Upon completion of a certification report and its sign-off by management, additional work is required. Training will be needed in order to educate workers and facility managers of the requirements of lightning certification. Operating procedures will need to be generated and/or modified with additional controls. Engineering controls may also be implemented requiring the modification of cells. Careful planning should bring most of these issues to light, making it clear where this document is helpful and were additional assistance may be necessary.« less

Lightning swept-stroke attachment patterns and flight conditions for storm hazards 1981

NASA Technical Reports Server (NTRS)

Fisher, B. D.

1984-01-01

As part of the NASA Langley Research Center Storm Hazards Program, 111 thunderstorm penetrations were made in 1981 with an F-106B airplane in order to record direct-strike lightning data and the associated flight conditions. Ground-based weather radar measurements in conjunction with these penetrations were made by NOAA National Severe Storms Laboratory in Oklahoma and by NASA Wallops Flight Facility in Virginia. In 1981, the airplane received 10 direct lightning strikes; in addition, lightning transient data were recorded from 22 nearby flashes. Following each flight, the airplane was thoroughly inspected for evidence of lightning attachment, and the individual lightning attachment points were plotted on isometric projections of the airplane to identify swept-flash patterns. This report shows the strike attachment patterns that were found, and tabulates the flight conditions at the time of each lightning event. Finally, this paper contains a table in which the data in this report are cross-referenced with the previously published electromagnetic waveform data recorded onboard the airplane.

Regulatory Guidance for Lightning Protection in Nuclear Power Plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kisner, Roger A; Wilgen, John B; Ewing, Paul D

2006-01-01

Abstract - Oak Ridge National Laboratory (ORNL) was engaged by the U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research (RES) to develop the technical basis for regulatory guidance to address design and implementation practices for lightning protection systems in nuclear power plants (NPPs). Lightning protection is becoming increasingly important with the advent of digital and low-voltage analog systems in NPPs. These systems have the potential to be more vulnerable than older analog systems to the resulting power surges and electromagnetic interference (EMI) when lightning strikes facilities or power lines. This paper discusses the technical basis for guidance tomore » licensees and applicants covered in Regulatory Guide (RG) 1.204, Guidelines for Lightning Protection of Nuclear Power Plants, issued August 2005. RG 1.204 describes guidance for practices that are acceptable to the NRC staff for protecting nuclear power structures and systems from direct lightning strikes and the resulting secondary effects.« less

Regulatory guidance for lightning protection in nuclear power plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kisner, R. A.; Wilgen, J. B.; Ewing, P. D.

2006-07-01

Oak Ridge National Laboratory (ORNL) was engaged by the U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research (RES) to develop the technical basis for regulatory guidance to address design and implementation practices for lightning protection systems in nuclear power plants (NPPs). Lightning protection is becoming increasingly important with the advent of digital and low-voltage analog systems in NPPs. These systems have the potential to be more vulnerable than older analog systems to the resulting power surges and electromagnetic interference (EMI) when lightning strikes facilities or power lines. This paper discusses the technical basis for guidance to licensees andmore » applicants covered in Regulatory Guide (RG) 1.204, Guidelines for Lightning Protection of Nuclear Power Plants, issued August 2005. RG 1.204 describes guidance for practices that are acceptable to the NRC staff for protecting nuclear power structures and systems from direct lightning strikes and the resulting secondary effects. (authors)« less

Tropic lightning: myth or menace?

PubMed

McCarthy, John

2014-11-01

Lightning is one of the leading causes of death related to environmental disaster. Of all lightning fatalities documented between 2006 and 2012, leisure activities contributed the largest proportion of deaths, with water-associated, sports, and camping being the most common. Despite the prevalence of these activities throughout the islands, Hawai'i has had zero documented lightning fatalities since weather data tracking was initiated in 1959. There is a common misconception that lightning does not strike the ground in Hawai'i. This myth may contribute to a potentially dangerous false sense of security, and recognition of warning signs and risk factor modification remain the most important prevention strategies. Lightning damage occurs on a spectrum, from minor burns to multi-organ dysfunction. After injury, initial treatment should focus on "reverse triage" and immediate cardiopulmonary resuscitation when indicated, followed by transfer to a healthcare facility. Definitive treatment entails monitoring and management of potential sequelae, to include cardiovascular, neurologic, dermatologic, ophthalmologic, audiovestibular, and psychiatric complications.

KSC-04PD-1316

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility, Mike Bolt holds the Stanley Cup, won this year by the National Hockey Leagues Tampa Bay Lightning. Bolt is the Stanley Cup keeper. The cup was also briefly available for viewing by employees in the KSC Training Auditorium. Jay Feaster, general manager of the Tampa Bay Lightning, brought the cup to KSC while on a tour. The Stanley Cup weighs 35 pounds and is more than 100 years old. The Lightning will be added to the cup in September.

Objective Lightning Forecasting at Kennedy Space Center and Cape Canaveral Air Force Station using Cloud-to-Ground Lightning Surveillance System Data

NASA Technical Reports Server (NTRS)

Lambert, Winfred; Wheeler, Mark; Roeder, William

2005-01-01

The 45th Weather Squadron (45 WS) at Cape Canaveral Air-Force Station (CCAFS)ln Florida issues a probability of lightning occurrence in their daily 24-hour and weekly planning forecasts. This information is used for general planning of operations at CCAFS and Kennedy Space Center (KSC). These facilities are located in east-central Florida at the east end of a corridor known as 'Lightning Alley', an indication that lightning has a large impact on space-lift operations. Much of the current lightning probability forecast is based on a subjective analysis of model and observational data and an objective forecast tool developed over 30 years ago. The 45 WS requested that a new lightning probability forecast tool based on statistical analysis of more recent historical warm season (May-September) data be developed in order to increase the objectivity of the daily thunderstorm probability forecast. The resulting tool is a set of statistical lightning forecast equations, one for each month of the warm season, that provide a lightning occurrence probability for the day by 1100 UTC (0700 EDT) during the warm season.

21st Century Lightning Protection for High Altitude Observatories

NASA Astrophysics Data System (ADS)

Kithil, Richard

2013-05-01

One of the first recorded lightning insults to an observatory was in January 1890 at the Ben Nevis Observatory in Scotland. In more recent times lightning has caused equipment losses and data destruction at the US Air Force Maui Space Surveillance Complex, the Cerro Tololo observatory and the nearby La Serena scientific and technical office, the VLLA, and the Apache Point Observatory. In August 1997 NOAA's Climate Monitoring and Diagnostic Laboratory at Mauna Loa Observatory was out of commission for a month due to lightning outages to data acquisition computers and connected cabling. The University of Arizona has reported "lightning strikes have taken a heavy toll at all Steward Observatory sites." At Kitt Peak, extensive power down protocols are in place where lightning protection for personnel, electrical systems, associated electronics and data are critical. Designstage lightning protection defenses are to be incorporated at NSO's ATST Hawaii facility. For high altitude observatories lightning protection no longer is as simple as Franklin's 1752 invention of a rod in the air, one in the ground and a connecting conductor. This paper discusses selection of engineered lightning protection subsystems in a carefully planned methodology which is specific to each site.

A Wrf-Chem Flash Rate Parameterization Scheme and LNO(x) Analysis of the 29-30 May 2012 Convective Event in Oklahoma During DC3

NASA Technical Reports Server (NTRS)

Cummings, Kristin A.; Pickering, Kenneth E.; Barth, M.; Weinheimer, A.; Bela, M.; Li, Y.; Allen, D.; Bruning, E.; MacGorman, D.; Rutledge, S.;

A WRF-Chem Flash Rate Parameterization Scheme and LNOx Analysis of the 29-30 May 2012 Convective Event in Oklahoma During DC3

NASA Technical Reports Server (NTRS)

Cummings, Kristin A.; Pickering, Kenneth E.; Barth, M.; Weinheimer, A.; Bela, M.; Li, Y.; Allen, D.; Bruning, E.; MacGorman, D.; Rutledge, S.;

Estimation of Lightning Levels on a Launcher Using a BEM-Compressed Model

NASA Astrophysics Data System (ADS)

Silly, J.; Chaigne, B.; Aspas-Puertolas, J.; Herlem, Y.

2016-05-01

As development cycles in the space industry are being considerably reduced, it seems mandatory to deploy in parallel fast analysis methods for engineering purposes, but without sacrificing accuracy. In this paper we present the application of such methods to early Phase A-B [1] evaluation of lightning constraints on a launch vehicle.A complete 3D parametric model of a launcher has been thus developed and simulated with a Boundary Element Method (BEM)-frequency simulator (equipped with a low frequency algorithm). The time domain values of the observed currents and fields are obtained by post-treatment using an inverse discrete Fourier transform (IDFT).This model is used for lightning studies, especially the simulation are useful to analyse the influence of lightning injected currents on resulting circulated currents on external cable raceways. The description of the model and some of those results are presented in this article.

Simulation of the Universal-Time Diurnal Variation of the Global Electric Circuit Charging Rate

NASA Technical Reports Server (NTRS)

Mackerras, D.; Darvenzia, M.; Orville, R. E.; Williams, E. R.; Goodman, S. J.

1999-01-01

A global lightning model that includes diurnal and annual lightning variation, and total flash density versus latitude for each major land and ocean, has been used as the basis for simulating the global electric circuit charging rate. A particular objective has been to reconcile the difference in amplitude ratios [AR=(max-min)/mean] between global lightning diurnal variation (AR approx. = 0.8) and the diurnal variation of typical atmospheric potential gradient curves (AR approx. = 0.35). A constraint on the simulation is that the annual mean charging current should be about 1000 A. The global lightning model shows that negative ground flashes can contribute, at most, about 10-15% of the required current. For the purpose of the charging rate simulation, it was assumed that each ground flash contributes 5 C to the charging process. It was necessary to assume that all electrified clouds contribute to charging by means other than lightning, that the total flash rate can serve as an indirect indicator of the rate of charge transfer, and that oceanic electrified clouds contribute to charging even though they are relatively inefficient in producing lightning. It was also found necessary to add a diurnally invariant charging current component. By trial and error it was found that charging rate diurnal variation curves in Universal time (UT) could be produced with amplitude ratios and general shapes similar to those of the potential gradient diurnal variation curves measured over ocean and arctic regions during voyages of the Carnegie Institute research vessels.

Lightning NOx Production and Its Consequences for Tropospheric Chemistry

NASA Technical Reports Server (NTRS)

Pickering, Kenneth E.

2005-01-01

Cloud-resolving case-study simulations of convective transport and lightning NO production have yielded results which are directly applicable to the design of lightning parameterizations for global chemical transport models. In this work we have used cloud-resolving models (the Goddard Cumulus Ensemble Model (GCE) and MMS) to drive an off-line cloud-scale chemical transport model (CSCTM). The CSCTM, in conjunction with aircraft measurements of NO x in thunderstorms and ground-l;>ased lightning observations, has been used to constrain the amount of NO produced per flash. Cloud and chemistry simulations for several case studies of storms in different environments will be presented. Observed lightning flash rates have been incorporated into the CSCTM, and several scenarios of NO production per intracloud (IC) and per cloud-to-ground (CG) flash have been tested for each storm. The resulting NOx mixing ratios are compared with aircraft measurements taken within the storm (typically the anvil region) to determine the most likely NO production scenario. The range of values of NO production per flash (or per meter of lightning channel length) that have been deduced from the model will be shown and compared with values of production in the literature that have been deduced from observed NO spikes and from anvil flux calculations. Results show that on a per flash basis, IC flashes are nearly as productive of NO as CG flashes. This result simplifies the lightning parameterization for global models (ie., an algorithm for estimating the IC/CG ratio is not necessary). Vertical profiles of lightning NOx mass at the end of the 3-D storm simulations have been summarized to yield suggested profiles for use in global models. Estimates of mean NO production per flash vary by a factor of three from one simulated storm to another. When combined with the global flash rate of 44 flashes per second from NASA's Optical Transient Detector (OTD) measurements, these estimates and the results from other techniques yield global NO production rates of2-9 TgN/year. Simulations of the photochemistry over the 24 hours following a storm has been performed to determine the additional ozone production which can be attributed to lightning NO. Convective transport of HOx precursors leads to the generation of a HOx plume which substantially aids the downstream ozone production.

Description of an aircraft lightning and simulated nuclear electromagnetic pulse (NEMP) threat based on experimental data

NASA Technical Reports Server (NTRS)

Rustan, Pedro L., Jr.

1987-01-01

Lightning data obtained by measuring the surface electromagnetic fields on a CV-580 research aircraft during 48 lightning strikes between 1500 and 18,000 feet in central Florida during the summers of 1984 and 1985, and nuclear electromagnetic pulse (NEMP) data obtained by surface electromagnetic field measurements using a 1:74 CV-580 scale model, are presented. From one lightning event, maximum values of 3750 T/s for the time rate of change of the surface magnetic flux density, and 4.7 kA for the peak current, were obtained. From the simulated NEMP test, maximum values of 40,000 T/s for the time rate of change of the surface magnetic flux density, and 90 A/sq m for the total normal current density, were found. The data have application to the development of a military aircraft lightning/NEMP standard.

Lightning protection of distribution lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDermott, T.E.; Short, T.A.; Anderson, J.G.

1994-01-01

This paper reports a study of distribution line lightning performance, using computer simulations of lightning overvoltages. The results of previous investigations are extended with a detailed model of induced voltages from nearby strokes, coupled into a realistic power system model. The paper also considers the energy duty of distribution-class surge arresters exposed to direct strokes. The principal result is that widely separated pole-top arresters can effectively protect a distribution line from induced-voltage flashovers. This means that nearby lightning strokes need not be a significant lightning performance problem for most distribution lines.

Lightning NOx and Impacts on Air Quality

NASA Technical Reports Server (NTRS)

Murray, Lee T.

2016-01-01

Lightning generates relatively large but uncertain quantities of nitrogen oxides, critical precursors for ozone and hydroxyl radical (OH), the primary tropospheric oxidants. Lightning nitrogen oxide strongly influences background ozone and OH due to high ozone production efficiencies in the free troposphere, effecting small but non-negligible contributions to surface pollutant concentrations. Lightning globally contributes 3-4 ppbv of simulated annual-mean policy-relevant background (PRB) surface ozone, comprised of local, regional, and hemispheric components, and up to 18 ppbv during individual events. Feedbacks via methane may counter some of these effects on decadal time scales. Lightning contributes approximately 1 percent to annual-mean surface particulate matter, as a direct precursor and by promoting faster oxidation of other precursors. Lightning also ignites wildfires and contributes to nitrogen deposition. Urban pollution influences lightning itself, with implications for regional lightning-nitrogen oxide production and feedbacks on downwind surface pollution. How lightning emissions will change in a warming world remains uncertain.

Electromagnetic environmental criteria for US Army missile systems - EMC, EMR, EMI, EMP, ESD, and lightning

NASA Astrophysics Data System (ADS)

Ponds, Charles D.; Knaur, James A.

1988-01-01

This paper presents the design and test requirements in developing an electromagnetic compatibility missile system. Environmental levels are presented for electromagnetic radiation hazards, electromagnetic radiation operational, electrostatic discharge, lightning, and electromagnetic pulse (nuclear). Testing techniques and facility capabilities are presented for research and development testing of missile systems.

Lightning initiation mechanism based on the development of relativistic runaway electron avalanches triggered by background cosmic radiation: Numerical simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babich, L. P., E-mail: babich@elph.vniief.ru; Bochkov, E. I.; Kutsyk, I. M.

2011-05-15

The mechanism of lightning initiation due to electric field enhancement by the polarization of a conducting channel produced by relativistic runaway electron avalanches triggered by background cosmic radiation has been simulated numerically. It is shown that the fields at which the start of a lightning leader is possible even in the absence of precipitations are locally realized for realistic thundercloud configurations and charges. The computational results agree with the in-situ observations of penetrating radiation enhancement in thunderclouds.

Rocket-triggered lightning strikes and forest fire ignition

NASA Technical Reports Server (NTRS)

Fenner, James H.

1989-01-01

Background information on the rocket-triggered lightning project at Kennedy Space Center (KSC), a summary of the forecasting problem there, the facilities and equipment available for undertaking field experiments at KSC, previous research activity performed, a description of the atmospheric science field laboratory near Mosquito Lagoon on the KSC complex, methods of data acquisition, and present results are discussed. New sources of data for the 1989 field experiment include measuring the electric field in the lower few thousand feet of the atmosphere by suspending field measuring devices below a tethered balloon. Problems encountered during the 1989 field experiment are discussed. Future prospects for both triggered lightning and lightning-kindled forest fire research at KSC are listed.

Estimating Lightning NOx Emissions for Regional Air Quality Modeling

NASA Astrophysics Data System (ADS)

Holloway, T.; Scotty, E.; Harkey, M.

2014-12-01

Lightning emissions have long been recognized as an important source of nitrogen oxides (NOx) on a global scale, and an essential emission component for global atmospheric chemistry models. However, only in recent years have regional air quality models incorporated lightning NOx emissions into simulations. The growth in regional modeling of lightning emissions has been driven in part by comparisons with satellite-derived estimates of column NO2, especially from the Ozone Monitoring Instrument (OMI) aboard the Aura satellite. We present and evaluate a lightning inventory for the EPA Community Multiscale Air Quality (CMAQ) model. Our approach follows Koo et al. [2010] in the approach to spatially and temporally allocating a given total value based on cloud-top height and convective precipitation. However, we consider alternate total NOx emission values (which translate into alternate lightning emission factors) based on a review of the literature and performance evaluation against OMI NO2 for July 2007 conditions over the U.S. and parts of Canada and Mexico. The vertical distribution of lightning emissions follow a bimodal distribution from Allen et al. [2012] calculated over 27 vertical model layers. Total lightning NO emissions for July 2007 show the highest above-land emissions in Florida, southeastern Texas and southern Louisiana. Although agreement with OMI NO2 across the domain varied significantly depending on lightning NOx assumptions, agreement among the simulations at ground-based NO2 monitors from the EPA Air Quality System database showed no meaningful sensitivity to lightning NOx. Emissions are compared with prior studies, which find similar distribution patterns, but a wide range of calculated magnitudes.

Electrostatic protection of the solar power satellite and rectenna. Part 2: Lightning protection of the rectenna

NASA Technical Reports Server (NTRS)

1980-01-01

Computer simulations and laboratory tests were used to evaluate the hazard posed by lightning flashes to ground on the Solar Power Satellite rectenna and to make recommendations on a lightning protection system for the rectenna. The distribution of lightning over the lower 48 of the continental United States was determined, as were the interactions of lightning with the rectenna and the modes in which those interactions could damage the rectenna. Lightning protection was both required and feasible. Several systems of lightning protection were considered and evaluated. These included two systems that employed lightning rods of different lengths and placed on top of the rectenna's billboards and a third, distribution companies; it consists of short lightning rods all along the length of each billboard that are connected by a horizontal wire above the billboard. The distributed lightning protection system afforded greater protection than the other systems considered and was easier to integrate into the rectenna's structural design.

Monte Carlo Simulation to Estimate Likelihood of Direct Lightning Strikes

NASA Technical Reports Server (NTRS)

Mata, Carlos; Medelius, Pedro

2008-01-01

A software tool has been designed to quantify the lightning exposure at launch sites of the stack at the pads under different configurations. In order to predict lightning strikes to generic structures, this model uses leaders whose origins (in the x-y plane) are obtained from a 2D random, normal distribution.

Numerical modeling of an intense precipitation event and its associated lightning activity over northern Greece

NASA Astrophysics Data System (ADS)

Pytharoulis, I.; Kotsopoulos, S.; Tegoulias, I.; Kartsios, S.; Bampzelis, D.; Karacostas, T.

2016-03-01

This study investigates an intense precipitation event and its lightning activity that affected northern Greece and primarily Thessaloniki on 15 July 2014. The precipitation measurement of 98.5 mm in 15 h at the Aristotle University of Thessaloniki set a new absolute record maximum. The thermodynamic analysis indicated that the event took place in an environment that could support deep thunderstorm activity. The development of this intense event was associated with significant low-level convergence and upper-level divergence even before its triggering and a positive vertical gradient of relative vorticity advection. The high resolution (1.667 km × 1.667 km) non-hydrostatic WRF-ARW numerical weather prediction model was used to simulate this intense precipitation event, while the Lightning Potential Index was utilized to calculate the potential for lightning activity. Sensitivity experiments suggested that although the strong synoptic forcing assumed primary role in the occurrence of intense precipitation and lightning activity, their spatiotemporal variability was affected by topography. The application of the very fine resolution topography of NASA Shuttle Radar Topographic Mission improved the simulated precipitation and the calculated lightning potential.

Situational Lightning Climatologies

NASA Technical Reports Server (NTRS)

Bauman, William; Crawford, Winifred

2010-01-01

Research has revealed distinct spatial and temporal distributions of lightning occurrence that are strongly influenced by large-scale atmospheric flow regimes. It was believed there were two flow systems, but it has been discovered that actually there are seven distinct flow regimes. The Applied Meteorology Unit (AMU) has recalculated the lightning climatologies for the Shuttle Landing Facility (SLF), and the eight airfields in the National Weather Service in Melbourne (NWS MLB) County Warning Area (CWA) using individual lightning strike data to improve the accuracy of the climatologies. The software determines the location of each CG lightning strike with 5-, 10-, 20-, and 30-nmi (.9.3-, 18.5-, 37-, 55.6-km) radii from each airfield. Each CG lightning strike is binned at 1-, 3-, and 6-hour intervals at each specified radius. The software merges the CG lightning strike time intervals and distance with each wind flow regime and creates probability statistics for each time interval, radii, and flow regime, and stratifies them by month and warm season. The AMU also updated the graphical user interface (GUI) with the new data.

Fast animation of lightning using an adaptive mesh.

PubMed

Kim, Theodore; Lin, Ming C

2007-01-01

We present a fast method for simulating, animating, and rendering lightning using adaptive grids. The "dielectric breakdown model" is an elegant algorithm for electrical pattern formation that we extend to enable animation of lightning. The simulation can be slow, particularly in 3D, because it involves solving a large Poisson problem. Losasso et al. recently proposed an octree data structure for simulating water and smoke, and we show that this discretization can be applied to the problem of lightning simulation as well. However, implementing the incomplete Cholesky conjugate gradient (ICCG) solver for this problem can be daunting, so we provide an extensive discussion of implementation issues. ICCG solvers can usually be accelerated using "Eisenstat's trick," but the trick cannot be directly applied to the adaptive case. Fortunately, we show that an "almost incomplete Cholesky" factorization can be computed so that Eisenstat's trick can still be used. We then present a fast rendering method based on convolution that is competitive with Monte Carlo ray tracing but orders of magnitude faster, and we also show how to further improve the visual results using jittering.

Lightning Channel Corona Formation Treated as a Large System of Streamers

NASA Astrophysics Data System (ADS)

Carlson, B.; Lehtinen, N. G.; Kochkin, P.

2017-12-01

Transfer of charge along a lightning channel leads to strong electric fields that drive such charge outward. This charge flow is nonuniform, breaking up into millimeter-scale discharge structures called streamers. The motion of such streamers can carry charge many meters outward from the channel, but each individual streamer only carries a small amount of charge. Transfer of macroscopic charge outward thus requires a large population of streamers that are expected to interact and exhibit interesting collective behaviors. We attempt to simulate such collective behaviors by approximating the behavior of each streamer but retaining streamer interactions and overall electrodynamic effects and apply this simulation to a few key scenarios. For the case of flow of charge off a lightning channel, we simulate a continually growing population of streamers injected near a charged conducting channel. Further, motivated by lightning initiation, we simulate the growth of a population of streamers from a single seed streamer as might initiate from a hydrometeor. For all cases considered, we characterize the charges and currents involved, compare to observations where possible, and characterize the collective effects including spatial and temporal non-uniformity.

Tropic Lightning: Myth or Menace?

PubMed Central

2014-01-01

Lightning is one of the leading causes of death related to environmental disaster. Of all lightning fatalities documented between 2006 and 2012, leisure activities contributed the largest proportion of deaths, with water-associated, sports, and camping being the most common. Despite the prevalence of these activities throughout the islands, Hawai‘i has had zero documented lightning fatalities since weather data tracking was initiated in 1959. There is a common misconception that lightning does not strike the ground in Hawai‘i. This myth may contribute to a potentially dangerous false sense of security, and recognition of warning signs and risk factor modification remain the most important prevention strategies. Lightning damage occurs on a spectrum, from minor burns to multi-organ dysfunction. After injury, initial treatment should focus on “reverse triage” and immediate cardiopulmonary resuscitation when indicated, followed by transfer to a healthcare facility. Definitive treatment entails monitoring and management of potential sequelae, to include cardiovascular, neurologic, dermatologic, ophthalmologic, audiovestibular, and psychiatric complications. PMID:25478304

Experimental and Numerical Simulation Analysis of Typical Carbon Woven Fabric/Epoxy Laminates Subjected to Lightning Strike

NASA Astrophysics Data System (ADS)

Yin, J. J.; Chang, F.; Li, S. L.; Yao, X. L.; Sun, J. R.; Xiao, Y.

2017-12-01

To clarify the evolution of damage for typical carbon woven fabric/epoxy laminates exposed to lightning strike, artificial lightning testing on carbon woven fabric/epoxy laminates were conducted, damage was assessed using visual inspection and damage peeling approaches. Relationships between damage size and action integral were also elucidated. Results showed that damage appearance of carbon woven fabric/epoxy laminate presents circular distribution, and center of the circle located at the lightning attachment point approximately, there exist no damage projected area dislocations for different layers, visual damage territory represents maximum damage scope; visible damage can be categorized into five modes: resin ablation, fiber fracture and sublimation, delamination, ablation scallops and block-shaped ply-lift; delamination damage due to resin pyrolysis and internal pressure exist obvious distinguish; project area of total damage is linear with action integral for the same type specimens, that of resin ablation damage is linear with action integral, but no correlation with specimen type, for all specimens, damage depth is linear with logarithm of action integral. The coupled thermal-electrical model constructed is capable to simulate the ablation damage for carbon woven fabric/epoxy laminates exposed to simulated lightning current through experimental verification.

Atmospheric electricity

NASA Astrophysics Data System (ADS)

Stepanenko, V. D.

Papers are presented on a wide range of studies of atmospheric electricity, from the problem of the global atmospheric-electricity circuit to the effects of atmospheric electricity on ground-based facilities and biological objects. The main topics considered are general problems of atmospheric electricity, studies of atmospheric ions and aerosols, cloud electricity, studies of lightning-storm activity and atmospherics, and lightning protection.

Preliminary Results From a Laboratory Study of Positive Streamer Discharges on Simulated Ice Hydrometeors

NASA Astrophysics Data System (ADS)

Petersen, D.; Bailey, M.; Hallett, J.; Beasley, W.

2007-12-01

The initiation of lightning remains an open question, due in large part to a deficit of in-situ observational evidence. Recent theoretical descriptions of lightning initiation have focused on runaway breakdown and related secondary processes, but have not convincingly explained the details of onset of the embryonic lightning leader channel. Among possible mechanisms contributing to the initial leader formation are positive streamer discharges from ice hydrometeors, themselves once favored as the primary explanation of lightning initiation. We present preliminary results from a new laboratory study of positive streamer discharges on simulated ice hydrometeors. Emphasis is given to precisely defining the minimum electric field strength required for onset of positive streamer generation, with variables of interest being ice crystal size, habit and environmental temperature.

Experimental and analytical investigation on metal damage suffered from simulated lightning currents

NASA Astrophysics Data System (ADS)

Yakun, LIU; Zhengcai, FU; Quanzhen, LIU; Baoquan, LIU; Anirban, GUHA

2017-12-01

The damage of two typical metal materials, Al alloy 3003 and steel alloy Q235B, subjected to four representative lightning current components are investigated by laboratory and analytical studies to provide fundamental data for lightning protection. The four lightning components simulating the natural lightning consist of the first return stroke, the continuing current of interval stroke, the long continuing current, and the subsequent stroke, with amplitudes 200 kA, 8 kA, 400 A, and 100 kA, respectively. The damage depth and area suffered from different lightning components are measured by the ultrasonic scanning system. And the temperature rise is measured by the thermal imaging camera. The results show that, for both Al 3003 and steel Q235B, the first return stroke component results in the largest damage area with damage depth 0.02 mm uttermost. The long continuing current component leads to the deepest damage depth of 3.3 mm for Al 3003 and much higher temperature rise than other components. The correlation analysis between damage results and lightning parameters indicates that the damage depth has a positive correlation with charge transfer. The damage area is mainly determined by the current amplitude and the temperature rise increases linearly with the charge transfer larger.

Aerosol indirect effect on tropospheric ozone via lightning

NASA Astrophysics Data System (ADS)

Yuan, Tianle; Remer, Lorraine A.; Bian, Huisheng; Ziemke, Jerald R.; Albrecht, Rachel; Pickering, Kenneth E.; Oreopoulos, Lazaros; Goodman, Steven J.; Yu, Hongbin; Allen, Dale J.

2012-09-01

Tropospheric ozone (O3) is a pollutant and major greenhouse gas and its radiative forcing is still uncertain. Inadequate understanding of processes related to O3 production, in particular those natural ones such as lightning, contributes to this uncertainty. Here we demonstrate a new effect of aerosol particles on O3production by affecting lightning activity and lightning-generated NOx (LNOx). We find that lightning flash rate increases at a remarkable rate of 30 times or more per unit of aerosol optical depth. We provide observational evidence that indicates the observed increase in lightning activity is caused by the influx of aerosols from a volcano. Satellite data analyses show O3is increased as a result of aerosol-induced increase in lightning and LNOx, which is supported by modle simulations with prescribed lightning change. O3production increase from this aerosol-lightning-ozone link is concentrated in the upper troposphere, where O3 is most efficient as a greenhouse gas. In the face of anthropogenic aerosol increase our findings suggest that lightning activity, LNOx and O3, especially in the upper troposphere, have all increased substantially since preindustrial time due to the proposed aerosol-lightning-ozone link, which implies a stronger O3 historical radiative forcing. Aerosol forcing therefore has a warming component via its effect on O3 production and this component has mostly been ignored in previous studies of climate forcing related to O3and aerosols. Sensitivity simulations suggest that 4-8% increase of column tropospheric ozone, mainly in the tropics, is expected if aerosol-lighting-ozone link is parameterized, depending on the background emission scenario. We note, however, substantial uncertainties remain on the exact magnitude of aerosol effect on tropospheric O3 via lightning. The challenges for obtaining a quantitative global estimate of this effect are also discussed. Our results have significant implications for understanding past and projecting future tropospheric O3forcing as well as wildfire changes and call for integrated investigations of the coupled aerosol-cloud-chemistry system.

Can High-resolution WRF Simulations Be Used for Short-term Forecasting of Lightning?

NASA Technical Reports Server (NTRS)

Goodman, S. J.; Lapenta, W.; McCaul, E. W., Jr.; LaCasse, K.; Petersen, W.

2006-01-01

A number of research teams have begun to make quasi-operational forecast simulations at high resolution with models such as the Weather Research and Forecast (WRF) model. These model runs have used horizontal meshes of 2-4 km grid spacing, and thus resolved convective storms explicitly. In the light of recent global satellite-based observational studies that reveal robust relationships between total lightning flash rates and integrated amounts of precipitation-size ice hydrometeors in storms, it is natural to inquire about the capabilities of these convection-resolving models in representing the ice hydrometeor fields faithfully. If they do, this might make operational short-term forecasts of lightning activity feasible. We examine high-resolution WRF simulations from several Southeastern cases for which either NLDN or LMA lightning data were available. All the WRF runs use a standard microphysics package that depicts only three ice species, cloud ice, snow and graupel. The realism of the WRF simulations is examined by comparisons with both lightning and radar observations and with additional even higher-resolution cloud-resolving model runs. Preliminary findings are encouraging in that they suggest that WRF often makes convective storms of the proper size in approximately the right location, but they also indicate that higher resolution and better hydrometeor microphysics would be helpful in improving the realism of the updraft strengths, reflectivity and ice hydrometeor fields.

Fly's Eye GLM Simulator

NASA Image and Video Library

2017-07-27

The Fly’s Eye GLM Simulator (FEGS) is an airborne array of multi-spectral radiometers optimized to measure the optical emission from lightning. The instrument was designed by the Lightning Group in the Earth Science Office at the Marshall Space Flight Center as part of the validation effort for the first Geostationary Lightning Mapper (GLM) onboard GOES-16. From March to May of 2017, FEGS was flown on the NASA Armstrong Flight Research Center ER-2 along with a payload of other instruments during the GOES-16 Validation Flight Campaign. Data collected during the campaign are being analyzed by scientists at NASA and collaborating institutions to test the accuracy of GLM and other GOES-16 instruments. FEGS adds the capability to investigate sub-millisecond lightning energetics to the NASA Airborne Earth Science program. When flown with its complimentary suite of instruments, the FEGS package observes lightning radiation signatures that span from radio frequencies to gamma-ray emission. Learn more about the GOES-16 Validation Flight Campaign here: https://www.youtube.com/watch?v=rCTIk...

Test Report: Direct and Indirect Lightning Effects on Composite Materials

NASA Technical Reports Server (NTRS)

Evans, R. W.

1997-01-01

Lightning tests were performed on composite materials as a part of an investigation of electromagnetic effects on the materials. Samples were subjected to direct and remote simulated lightning strikes. Samples included various thicknesses of graphite filament reinforced plastic (GFRP), material enhanced by expanded aluminum foil layers, and material with an aluminum honeycomb core. Shielding properties of the material and damage to the sample surfaces and joints were investigated. Adding expanded aluminum foil layers and increasing the thickness of GFRP improves the shielding effectiveness against lightning induced fields and the ability to withstand lightning strikes. A report describing the lightning strike tests performed by the U.S. Army Redstone Technical Test Center, Redstone Arsenal, AL, STERT-TE-E-EM, is included as an appendix.

Radiative effects due to North American anthropogenic and lightning emissions: Global and regional modeling

NASA Astrophysics Data System (ADS)

Martini, Matus Novak

We analyze the contribution of North American (NA) lightning and anthropogenic emissions to summertime ozone concentrations, radiative forcing, and exports from North America using the global University of Maryland chemistry transport model (UMD-CTM) and the regional scale Weather Research and Forecasting model with chemistry (WRF-Chem). Lightning NO contributes by 15--20 ppbv to upper tropospheric ozone concentrations over the United States with the effects of NA lightning on ozone seen as far east as North Africa and Europe. Using the UMD-CTM, we compare changes in surface and column ozone amounts due to the NOx State Implementation Plan (SIP) Call with the natural variability in ozone due to changes in meteorology and lightning. Comparing early summer 2004 with 2002, surface ozone decreased by up to 5 ppbv due to the NO x SIP Call while changes in meteorology and lightning resulted in a 0.3--1.4 ppbv increase in surface ozone. Ozone column variability was driven primarily by changes in lightning NO emissions, especially over the North Atlantic. As part of our WRF-Chem analysis, we modify the radiation schemes to use model-calculated ozone (interactive ozone) instead of climatological ozone profiles and conduct multiple 4-day simulations of July 2007. We found that interactive ozone increased the outgoing longwave radiation (OLR) by 3 W m-2 decreasing the bias with respect to remotely sensed OLR. The improvement is due to a high bias in the climatological ozone profiles. The interactive ozone had a small impact on mean upper troposphere temperature (-0.15°C). The UMD-CTM simulations indicate that NA anthropogenic emissions are responsible for more ozone export but less ozone radiative forcing than lightning NO emissions. Over the North Atlantic, NA anthropogenic emissions contributed 0.15--0.30 W m-2 to the net downward radiative flux at the tropopause while NA lightning contributed 0.30--0.50 W m-2. The ozone export from anthropogenic emissions was almost twice as large as that from lightning emissions. The WRF-Chem simulations show that the export of reactive nitrogen was 23%--28% of the boundary layer emissions and 26%--38% of the total emissions including lightning NO.

Atmospheric electricity/meteorology analysis

NASA Technical Reports Server (NTRS)

Goodman, Steven J.; Blakeslee, Richard; Buechler, Dennis

1993-01-01

This activity focuses on Lightning Imaging Sensor (LIS)/Lightning Mapper Sensor (LMS) algorithm development and applied research. Specifically we are exploring the relationships between (1) global and regional lightning activity and rainfall, and (2) storm electrical development, physics, and the role of the environment. U.S. composite radar-rainfall maps and ground strike lightning maps are used to understand lightning-rainfall relationships at the regional scale. These observations are then compared to SSM/I brightness temperatures to simulate LIS/TRMM multi-sensor algorithm data sets. These data sets are supplied to the WETNET project archive. WSR88-D (NEXRAD) data are also used as it becomes available. The results of this study allow us to examine the information content from lightning imaging sensors in low-earth and geostationary orbits. Analysis of tropical and U.S. data sets continues. A neural network/sensor fusion algorithm is being refined for objectively associating lightning and rainfall with their parent storm systems. Total lightning data from interferometers are being used in conjunction with data from the national lightning network. A 6-year lightning/rainfall climatology has been assembled for LIS sampling studies.

Investigation of severe lightning strike incidents to two USAF F-106A aircraft

NASA Technical Reports Server (NTRS)

Plumer, J. A.

1981-01-01

The results of the inspection and analysis of two F-106A aircraft that were struck by separate lightning strikes within a few minutes of each other are presented. Each aircraft sustained severe lightning strikes to the pitot booms, resulting in extensive damage to the pitot heater power harness, number 8 ground wire, and lightning suppressors, but there was no damage to either aircraft's electrical or avionic systems. A simulated lightning current of 226 kA and 3.8 million A(2)*S was required to reproduce the damage to the ground wires in the radomes. Photographs and detailed assessments of the damage are included.

A Three-Dimensional Total Odd Nitrogen (NO(y)) Simulation During SONEX using a Stretched-Grid Chemical Transport Model

NASA Technical Reports Server (NTRS)

Allen, Dale; Pickering, Kenneth; Stenchikov, Georgiy; Thompson, Anne M.; Kondo, Yutaka

1999-01-01

The relative importance of various odd nitrogen (NOy) sources including lightning, aircraft, and surface emissions on upper tropospheric total odd nitrogen is illustrated as a first application of the three-dimensional Stretched-Grid University of Maryland/Goddard Chemical-Transport Model (SG-GCTM). The SG-GCTM has been developed to look at the effect of localized sources and/or small scale mixing processes on the large-scale or global chemical balance. For this simulation, the stretched-arid was chosen so that its maximum resolution is located over eastern North America and the North Atlantic; a region that includes most of the SONEX (the SASS (Subsonic Assessment) Ozone and Nitrogen Oxides Experiment) flight paths. The SONEX period (October-November 1997) is simulated by driving the SG-GCTM with assimilated data from the GEOS-STRAT DAS (Goddard Earth Observing System-STRAT Data Assimilation System). A new algorithm is used to parameterize the lightning, flash rates that are needed to calculate emissions of NOy by lightning. Model-calculated upper tropospheric NOy and NOy measurements from the NASA DC-8 aircraft are compared. Spatial variations in NOy were well captured especially with the stretched-grid run; however, model-calculated concentrations were often too high in the upper troposphere, particularly during the first several flights. The lightning algorithm does a reasonably good job; however, the use of emissions from observed lightning, flashes significantly improves the simulation on a few occasions, especially November 3, 1997, indicating that significant uncertainty remains in parameterizing lightning in CTMS. Aircraft emissions play a relatively minor role (about 12%) in the upper tropospheric NOY budget averaged along SONEX flight paths; however, the contribution of such emmissions is as large as about 30% during portions of some flights.

Production of Lightning NO(x) and its Vertical Distribution Calculated from 3-D Cloud-scale Chemical Transport Model Simulations

NASA Technical Reports Server (NTRS)

Ott, Lesley; Pickering, Kenneth; Stenchikov, Georgiy; Allen, Dale; DeCaria, Alex; Ridley, Brian; Lin, Ruei-Fong; Lang, Steve; Tao, Wei-Kuo

2009-01-01

A 3-D cloud scale chemical transport model that includes a parameterized source of lightning NO(x), based on observed flash rates has been used to simulate six midlatitude and subtropical thunderstorms observed during four field projects. Production per intracloud (P(sub IC) and cloud-to-ground (P(sub CG)) flash is estimated by assuming various values of P(sub IC) and P(sub CG) for each storm and determining which production scenario yields NO(x) mixing ratios that compare most favorably with in-cloud aircraft observations. We obtain a mean P(sub CG) value of 500 moles NO (7 kg N) per flash. The results of this analysis also suggest that on average, P(sub IC) may be nearly equal to P(sub CG), which is contrary to the common assumption that intracloud flashes are significantly less productive of NO than are cloud-to-ground flashes. This study also presents vertical profiles of the mass of lightning NO(x), after convection based on 3-D cloud-scale model simulations. The results suggest that following convection, a large percentage of lightning NO(x), remains in the middle and upper troposphere where it originated, while only a small percentage is found near the surface. The results of this work differ from profiles calculated from 2-D cloud-scale model simulations with a simpler lightning parameterization that were peaked near the surface and in the upper troposphere (referred to as a "C-shaped" profile). The new model results (a backward C-shaped profile) suggest that chemical transport models that assume a C-shaped vertical profile of lightning NO(x) mass may place too much mass neat the surface and too little in the middle troposphere.

Simulation of the Universal-Time Diurnal Variation of the Global Electric Circuit Charging Rate

NASA Technical Reports Server (NTRS)

Mackerras, David; Darveniza, Mat; Orville, Richard E.; Williams, Earle R.; Goodman, Steven J.

1999-01-01

A global lightning model that includes diurnal and annual lightning variation, and total flash density versus latitude for each major land and ocean, has been used as the basis for simulating the global electric circuit charging rate. A particular objective has been to reconcile the difference in amplitude ratios [AR=(max-min)/mean] between global lightning diurnal variation (AR approximately equals 0.8) and the diurnal variation of typical atmospheric potential gradient curves (AR approximately equals 0.35). A constraint on the simulation is that the annual mean charging current should be about 1000 A. The global lightning model shows that negative ground flashes can contribute, at most, about 10-15% of the required current. For the purpose of the charging rate simulation, it was assumed that each ground flash contributes 5 C to the charging process. It was necessary to assume that all electrified clouds contribute to charging by means other than lightning, that the total flash rate can serve as an indirect indicator of the rate of charge transfer, and that oceanic electrified clouds contribute to charging even though they are relatively inefficient in producing lightning. It was also found necessary to add a diurnally invariant charging current component. By trial and error it was found that charging rate diurnal variation curves could be produced with amplitude ratios and general shapes similar to those of the potential gradient diurnal variation curves measured over ocean and arctic regions during voyages of the Carnegie Institute research vessels. The comparisons were made for the northern winter (Nov.-Feb.), the equinox (Mar., Apr., Sept., Oct.), the northern summer (May-Aug.), and the whole year.

Whistler Observations on DEMETER Compared with Full Electromagnetic Wave Simulations

NASA Astrophysics Data System (ADS)

Compston, A. J.; Cohen, M.; Lehtinen, N. G.; Inan, U.; Linscott, I.; Said, R.; Parrot, M.

2014-12-01

Terrestrial Very Low Frequency (VLF) electromagnetic radiation, which strongly impacts the Van Allen radiation belt electron dynamics, is injected across the ionosphere into the Earth's plasmasphere from two primary sources: man-made VLF transmitters and lightning discharges. Numerical models of trans-ionospheric propagation of such waves remain unvalidated, and early models may have overestimated the absorption, hindering a comprehensive understanding of the global impact of VLF waves in the loss of radiation belt electrons. In an attempt to remedy the problem of a lack of accurate trans-ionospheric propagation models, we have used a full electromagnetic wave method (FWM) numerical code to simulate the propagation of lightning-generated whistlers into the magnetosphere and compared the results with whistlers observed on the DEMETER satellite and paired with lightning stroke data from the National Lightning Detection Network (NLDN). We have identified over 20,000 whistlers occuring in 14 different passes of DEMETER over the central United States during the summer of 2009, and 14,000 of those occured within the 2000 km x 2000 km simulation grid we used. As shown in the attached figure, which shows a histogram of the ratio of the simulated whistler energy to the measured whistler energy for the 14,000 whistlers we compared, the simulation tends to slightly underestimate the total whistler energy injected by about 5 dB. However, the simulation underestimates the DEMETER measurements more as one gets further from the source lightning stroke, so since the signal to noise ratio of more distant whistlers will be smaller, possibly additive noise in the DEMETER measurements (which of course is not accounted for in the model) may explain some of the observed discrepancy.

ELVES Research at the Pierre Auger Observatory: Optical Emission Simulation and Time Evolution, WWLLN-LIS-Auger Correlations, and Double ELVES Observations and Simulation.

NASA Astrophysics Data System (ADS)

Merenda, K. D.

2016-12-01

Since 2013, the Pierre Auger Cosmic Ray Observatory in Mendoza, Argentina, extended its trigger algorithm to detect emissions of light consistent with the signature from very low frequency perturbations due to electromagnetic pulse sources (ELVES). Correlations with the World Wide Lightning Location Network (WWLLN), the Lightning Imaging Sensor (LIS) and simulated events were used to assess the quality of the reconstructed data. The FD is a pixel array telescope sensitive to the deep UV emissions of ELVES. The detector provides the finest time resolution of 100 nanoseconds ever applied to the study of ELVES. Four eyes, separated by approximately 40 kilometers, consist of six telescopes and span a total of 360 degrees of azimuth angle. The detector operates at night when storms are not in the field of view. An existing 3D EMP Model solves Maxwell's equations using a three dimensional finite-difference time-domain model to describe the propagation of electromagnetic pulses from lightning sources to the ionosphere. The simulation also provides a projection of the resulting ELVES onto the pixel array of the FD. A full reconstruction of simulated events is under development. We introduce the analog signal time evolution comparison between Auger reconstructed data and simulated events on individual FD pixels. In conjunction, we will present a study of the angular distribution of light emission around the vertical and above the causative lightning source. We will also contrast, with Monte Carlo, Auger double ELVES events separated by at most 5 microseconds. These events are too short to be explained by multiple return strokes, ground reflections, or compact intra-cloud lightning sources. Reconstructed ELVES data is 40% correlated to WWLLN data and an analysis with the LIS database is underway.

Aerosol indirect effect on tropospheric ozone via lightning

NASA Astrophysics Data System (ADS)

Yuan, T.; Remer, L. A.; Bian, H.; Ziemke, J. R.; Albrecht, R. I.; Pickering, K. E.; Oreopoulos, L.; Goodman, S. J.; Yu, H.; Allen, D. J.

2012-12-01

Tropospheric ozone (O3) is a pollutant and major greenhouse gas and its radiative forcing is still uncertain. The unresolved difference between modeled and observed natural background O3 concentrations is a key source of the uncertainty. Here we demonstrate remarkable sensitivity of lightning activity to aerosol loading with lightning activity increasing more than 30 times per unit of aerosol optical depth over our study area. We provide observational evidence that indicates the observed increase in lightning activity is caused by the influx of aerosols from a volcano. Satellite data analyses suggest O3 is increased as a result of aerosol-induced increase in lightning and lightning produced NOx. Model simulations with prescribed lightning change corroborate the satellite data analysis. This aerosol-O3 connection is achieved via aerosol increasing lightning and thus lightning produced nitrogen oxides. This aerosol-lightning-ozone link provides a potential physical mechanism that may account for a part of the model-observation difference in background O3 concentration. More importantly, O3 production increase from this link is concentrated in the upper troposphere, where O3 is most efficient as a greenhouse gas. Both of these implications suggest a stronger O3 historical radiative forcing. This introduces a new pathway, through which increasing in aerosols from pre-industrial time to present day enhances tropospheric O3 production. Aerosol forcing thus has a warming component via its effect on O3 production. Sensitivity simulations suggest that 4-8% increase of tropospheric ozone, mainly in the tropics, is expected if aerosol-lighting-ozone link is parameterized, depending on the background emission scenario. We note, however, substantial uncertainties remain on the exact magnitude of aerosol effect on tropospheric O3 via lightning. The challenges for obtaining a quantitative global estimate of this effect are also discussed. Our results have significant implications for understanding past and projecting future tropospheric O3 forcing as well as wildfire changes and call for integrated investigations of the coupled aerosol-cloud-chemistry system.

KSC-2009-3940

NASA Image and Video Library

2009-07-10

CAPE CANAVERAL, Fla. – A lightning strike on Launch Pad 39A at NASA's Kennedy Space Center in Florida is captured by an Operational Television camera. Eleven lightning strikes occurred within .35 miles of the pad during a thunderstorm July 10 as space shuttle Endeavour was prepared for launch. Mission managers decided to delay Endeavour's planned liftoff July 11 as a precaution to allow engineers and safety personnel time to analyze data and retest systems on the orbiter and solid rockets boosters. The next launch attempt for the STS-127 mission is planned for Sunday, July 12, at 7:13 p.m. EDT. The Operational Television cameras can be used to triangulate the location of lightning strikes. Other detection systems include the Cloud-To-Ground Lightning Surveillance System, Strikenet/National Lightning Detection Network, Lightning Induced Voltage Instrumentation System and the Catenary Wire Lightning Instrumentation System. Endeavour will deliver the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, in the final of three flights dedicated to the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory complex on the International Space Station. STS-127 is the 29th flight for the assembly of the space station. Photo credit: NASA/Analex

The October 25th 2015 super-cell storm over central Israel: numerical simulations with the WRF model

NASA Astrophysics Data System (ADS)

Lynn, Barry; Yair, Yoav

2017-04-01

We present high-resolution WRF simulations with lightning assimilation (Fierro et al., 2012; Lynn et al., 2015) coupled with the Dynamic Lightning Scheme (Lynn et al., 2012) of the October 25th 2015 super-cell event in the eastern Mediterranean. That storm developed within the northern tip of a Red-Sea trough off the Egyptian coastline near Alexandria, with deep convective cells rapidly growing over the sea, exhibiting cloud top temperatures colder than -70°C ( 18 km) and radar reflectivity cores > 65 dBz at 10 km. As the cells crossed the Israeli coast-line north of Tel-Aviv, they exhibited intensive lightning activity, severe hail, downbursts, and intense rain. The lightning detection system of the Israeli Electrical Corporation registered a total of over 17,000 CGs, and for 20 minutes at the peak of the event recorded CG flash-rates greater than 430 strokes per minute (if including IC strokes, it was likely higher). The results of the simulations properly reconstruct the rapid growth of vertically extensive high-reflectivity cores, with significant amounts of graupel, ice and supercooled water within the charging zone below -20C. This guaranteed the effectiveness of non-inductive charge separation processes leading to the exceptional flash rates that were observed. Fierro, A. O, E. R. Mansell, C. L. Ziegler, and D. R. MacGorman, 2012: Application of a Lightning Data Assimilation Technique in the WRF-ARW Model at Cloud-Resolving Scales for the Tornado Outbreak of 24 May 2011. Mon. Wea. Rev., 140, 2609-2627. Lynn, B. H., G. Kelman, and G. Ellrod, 2015: An Evaluation of the Efficacy of Using Observed Lightning to Improve Convective Lightning Forecasts. Wea. Forecasting, 30, 405-423. Lynn, B. H., Y. Yair, C. Price, G. Kelman, and A. J. Clark, 2012: Predicting cloud-to-ground and intracloud lightning in weather forecast models.Wea. Forecasting, 27, 1470-1488, doi:10.1175/WAF-D-11-00144.1.

Relativistic-microwave theory of ball lightning.

PubMed

Wu, H-C

2016-06-22

Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.

Relativistic-microwave theory of ball lightning

NASA Astrophysics Data System (ADS)

Wu, H.-C.

2016-06-01

Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.

Relativistic-microwave theory of ball lightning

PubMed Central

Wu, H.-C.

2016-01-01

Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics. PMID:27328835

Experimental Validation of Lightning-Induced Electromagnetic (Indirect) Coupling to Short Monopole Antennas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crull, E W; Brown Jr., C G; Perkins, M P

2008-07-30

For short monopoles in this low-power case, it has been shown that a simple circuit model is capable of accurate predictions for the shape and magnitude of the antenna response to lightning-generated electric field coupling effects, provided that the elements of the circuit model have accurate values. Numerical EM simulation can be used to provide more accurate values for the circuit elements than the simple analytical formulas, since the analytical formulas are used outside of their region of validity. However, even with the approximate analytical formulas the simple circuit model produces reasonable results, which would improve if more accurate analyticalmore » models were used. This report discusses the coupling analysis approaches taken to understand the interaction between a time-varying EM field and a short monopole antenna, within the context of lightning safety for nuclear weapons at DOE facilities. It describes the validation of a simple circuit model using laboratory study in order to understand the indirect coupling of energy into a part, and the resulting voltage. Results show that in this low-power case, the circuit model predicts peak voltages within approximately 32% using circuit component values obtained from analytical formulas and about 13% using circuit component values obtained from numerical EM simulation. We note that the analytical formulas are used outside of their region of validity. First, the antenna is insulated and not a bare wire and there are perhaps fringing field effects near the termination of the outer conductor that the formula does not take into account. Also, the effective height formula is for a monopole directly over a ground plane, while in the time-domain measurement setup the monopole is elevated above the ground plane by about 1.5-inch (refer to Figure 5).« less

A Fiber-Optic Aircraft Lightning Current Measurement Sensor

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

2013-01-01

A fiber-optic current sensor based on the Faraday Effect is developed for aircraft installations. It can measure total lightning current amplitudes and waveforms, including continuing current. Additional benefits include being small, lightweight, non-conducting, safe from electromagnetic interference, and free of hysteresis and saturation. The Faraday Effect causes light polarization to rotate in presence of magnetic field in the direction of light propagation. Measuring the total induced light polarization change yields the total current enclosed. The system operates at 1310nm laser wavelength and can measure approximately 300 A - 300 kA, a 60 dB range. A reflective polarimetric scheme is used, where the light polarization change is measured after a round-trip propagation through the fiber. A two-detector setup measures the two orthogonal polarizations for noise subtraction and improved dynamic range. The current response curve is non-linear and requires a simple spline-fit correction. Effects of high current were achieved in laboratory using combinations of multiple fiber and wire loops. Good result comparisons against reference sensors were achieved up to 300 kA. Accurate measurements on a simulated aircraft fuselage and an internal structure illustrate capabilities that maybe difficult with traditional sensors. Also tested at a commercial lightning test facility from 20 kA to 200 kA, accuracy within 3-10% was achieved even with non-optimum setups.

RSRM top hat cover simulator lightning test, volume 1

NASA Technical Reports Server (NTRS)

1990-01-01

The test sequence was to measure electric and magnetic fields induced inside a redesigned solid rocket motor case when a simulated lightning discharge strikes an exposed top hat cover simulator. The test sequence was conducted between 21 June and 17 July 1990. Thirty-six high rate-of-rise Marx generator discharges and eight high current bank discharges were injected onto three different test article configurations. Attach points included three locations on the top hat cover simulator and two locations on the mounting bolts. Top hat cover simulator and mounting bolt damage and grain cover damage was observed. Overall electric field levels were well below 30 kilowatts/meter. Electric field levels ranged from 184.7 to 345.9 volts/meter and magnetic field levels were calculated from 6.921 to 39.73 amperes/meter. It is recommended that the redesigned solid rocket motor top hat cover be used in Configuration 1 or Configuration 2 as an interim lightning protection device until a lightweight cover can be designed.

Low-pressure electrical discharge experiment to simulate high-altitude lightning above thunderclouds

NASA Technical Reports Server (NTRS)

Jarzembski, M. A.; Srivastava, V.

1995-01-01

Recently, extremely interesting high-altitude cloud-ionosphere electrical discharges, like lightning above thunderstorms, have been observed from NASA's space shuttle missions and during airborne and ground-based experiments. To understand these discharges, a new experiment was conceived to simulate a thundercloud in a vacuum chamber using a dielectric in particulate form into which electrodes were inserted to create charge centers analogous to those in an electrified cloud. To represent the ionosphere, a conducting medium (metallic plate) was introduced at the top of the chamber. It was found that for different pressures between approximately 1 and 300 mb, corresponding to various upper atmospheric altitudes, different discharges occurred above the simulated thundercloud, and these bore a remarkable similarity to the observed atmospheric phenomena. At pressures greater than 300 mb, these discharges were rare and only discharges within the simulated thundercloud were observed. Use of a particulate dielectric was critical for the successful simulation of the high-altitude lightning.

Effects of simulated lightning on composite and metallic joints

NASA Technical Reports Server (NTRS)

Howell, W. E.; Plumer, J. A.

1982-01-01

The effects of simulated lightning strikes and currents on aircraft bonded joints and access/inspection panels were investigated. Both metallic and composite specimens were tested. Tests on metal fuel feed through elbows in graphite/epoxy structures were evaluated. Sparking threshold and residual strength of single lap bonded joints and sparking threshold of access/inspection panels and metal fuel feed through elbows are reported.

On the Relationship between Observed NLDN Lightning ...

EPA Pesticide Factsheets

Lightning-produced nitrogen oxides (NOX=NO+NO2) in the middle and upper troposphere play an essential role in the production of ozone (O3) and influence the oxidizing capacity of the troposphere. Despite much effort in both observing and modeling lightning NOX during the past decade, considerable uncertainties still exist with the quantification of lightning NOX production and distribution in the troposphere. It is even more challenging for regional chemistry and transport models to accurately parameterize lightning NOX production and distribution in time and space. The Community Multiscale Air Quality Model (CMAQ) parameterizes the lightning NO emissions using local scaling factors adjusted by the convective precipitation rate that is predicted by the upstream meteorological model; the adjustment is based on the observed lightning strikes from the National Lightning Detection Network (NLDN). For this parameterization to be valid, the existence of an a priori reasonable relationship between the observed lightning strikes and the modeled convective precipitation rates is needed. In this study, we will present an analysis leveraged on the observed NLDN lightning strikes and CMAQ model simulations over the continental United States for a time period spanning over a decade. Based on the analysis, new parameterization scheme for lightning NOX will be proposed and the results will be evaluated. The proposed scheme will be beneficial to modeling exercises where the obs

Expanding the Operational Use of Total Lightning Ahead of GOES-R

NASA Technical Reports Server (NTRS)

Stano, Geoffrey T.; Wood, Lance; Garner, Tim; Nunez, Roland; Kann, Deirdre; Reynolds, James; Rydell, Nezette; Cox, Rob; Bobb, William R.

2015-01-01

NASA's Short-term Prediction Research and Transition Center (SPoRT) has been transitioning real-time total lightning observations from ground-based lightning mapping arrays since 2003. This initial effort was with the local Weather Forecast Offices (WFO) that could use the North Alabama Lightning Mapping Array (NALMA). These early collaborations established a strong interest in the use of total lightning for WFO operations. In particular the focus started with warning decision support, but has since expanded to include impact-based decision support and lightning safety. SPoRT has used its experience to establish connections with new lightning mapping arrays as they become available. The GOES-R / JPSS Visiting Scientist Program has enabled SPoRT to conduct visits to new partners and expand the number of operational users with access to total lightning observations. In early 2014, SPoRT conducted the most recent visiting scientist trips to meet with forecast offices that will used the Colorado, Houston, and Langmuir Lab (New Mexico) lightning mapping arrays. In addition, SPoRT met with the corresponding Center Weather Service Units (CWSUs) to expand collaborations with the aviation community. These visits were an opportunity to learn about the forecast needs of each office visited as well as to provide on-site training for the use of total lightning, setting the stage for a real-time assessment during May-July 2014. With five lightning mapping arrays covering multiple geographic locations, the 2014 assessment has demonstrated numerous uses of total lightning in varying situations. Several highlights include a much broader use of total lightning for impact-based decision support ranging from airport weather warnings, supporting fire crews, and protecting large outdoor events. The inclusion of the CWSUs has broadened the operational scope of total lightning, demonstrating how these data can support air traffic management, particularly in the Terminal Radar Approach Control Facilities (TRACON) region around an airport. These collaborations continue to demonstrate, from the operational perspective, the utility of total lightning and the importance of continued training and preparation in advance of the Geostationary Lightning Mapper.

Lightning Strike Ablation Damage Influence Factors Analysis of Carbon Fiber/Epoxy Composite Based on Coupled Electrical-Thermal Simulation

NASA Astrophysics Data System (ADS)

Yin, J. J.; Chang, F.; Li, S. L.; Yao, X. L.; Sun, J. R.; Xiao, Y.

2017-10-01

According to the mathematical analysis model constructed on the basis of energy-balance relationship in lightning strike, and accompany with the simplified calculation strategy of composite resin pyrolysis degree dependent electrical conductivity, an effective three dimensional thermal-electrical coupling analysis finite element model of composite laminate suffered from lightning current was established based on ABAQUS, to elucidate the effects of lighting current waveform parameters and thermal/electrical properties of composite laminate on the extent of ablation damage. Simulated predictions agree well with the composite lightning strike directed effect experimental data, illustrating the potential accuracy of the constructed model. The analytical results revealed that extent of composite lightning strike ablation damage can be characterized by action integral validly, there exist remarkable power function relationships between action integral and visual damage area, projected damage area, maximum damage depth and damage volume of ablation damage, and enhancing the electrical conductivity and specific heat of composite, ablation damage will be descended obviously, power function relationships also exist between electrical conductivity, specific heat and ablation damage, however, the impact of thermal conductivity on the extent of ablation damage is not notable. The conclusions obtained provide some guidance for composite anti-lightning strike structure-function integration design.

The use of a potential lightning index in multi-microphysical cloud-resolving simulations of a V-shape convective system.

NASA Astrophysics Data System (ADS)

Lagasio, Martina; Parodi, Antonio; Procopio, Renato; Rachidi, Farhad; Fiori, Elisabetta

2017-04-01

Lightning activity is a characteristic phenomenon of severe weather as confirmed by many studies on different weather regimes that reveal strong interplay between lightning phenomena and extreme rainfall process in thunderstorms. The improvement of the so-called total (i.e. cloud-to-ground and intra-cloud) lightning observation systems in the last decades has allowed to investigate the relationship between the lightning flash rate and the kinematic and microphysical properties of severe hydro-meteorological events characterized by strong convection. V-shape back-building Mesoscale Convective Systems (MCSs) occurring over short periods of time have hit several times the Liguria region located in north-western Italy in the period between October 2010 and November 2014, generating flash-flood events responsible for hundreds of fatalities and millions of euros of damage. All these events showed an area of intense precipitation sweeping an arc of a few degrees around the warm conveyor belt originating about 50-60 km from the Liguria coastline. A second main ingredient was the presence of a convergence line, which supported the development and the maintenance of the aforementioned back-building process. Other common features were the persistence of such geometric configuration for many hours and the associated strong lightning activity. A methodological approach for the evaluation of these types of extreme rainfall and lightning convective events is presented for a back-building MCS event occurred in Genoa in 2014. A microphysics driven ensemble of WRF simulations at cloud-permitting grid spacing (1 km) with different microphysics parameterizations is used and compared to the available observational radar and lightning data. To pursue this aim, the performance of the Lightning Potential Index (LPI) as a measure of the potential for charge generation and separation that leads to lightning occurrence in clouds, is computed and analyzed to gain further physical insight in these V-shape convective processes and to understand its predictive ability.

Evaluating lightning hazards to building environments using explicit numerical solutions of Maxwell's equations

NASA Astrophysics Data System (ADS)

Collier, Richard S.; McKenna, Paul M.; Perala, Rodney A.

1991-08-01

The objective here is to describe the lightning hazards to buildings and their internal environments using advanced formulations of Maxwell's Equations. The method described is the Three Dimensional Finite Difference Time Domain Solution. It can be used to solve for the lightning interaction with such structures in three dimensions with the inclusion of a considerable amount of detail. Special techniques were developed for including wire, plumbing, and rebar into the model. Some buildings have provisions for lightning protection in the form of air terminals connected to a ground counterpoise system. It is shown that fields and currents within these structures can be significantly high during a lightning strike. Time lapse video presentations were made showing the electric and magnetic field distributions on selected cross sections of the buildings during a simulated lightning strike.

Evaluating lightning hazards to building environments using explicit numerical solutions of Maxwell's equations

NASA Technical Reports Server (NTRS)

Collier, Richard S.; Mckenna, Paul M.; Perala, Rodney A.

1991-01-01

The objective here is to describe the lightning hazards to buildings and their internal environments using advanced formulations of Maxwell's Equations. The method described is the Three Dimensional Finite Difference Time Domain Solution. It can be used to solve for the lightning interaction with such structures in three dimensions with the inclusion of a considerable amount of detail. Special techniques were developed for including wire, plumbing, and rebar into the model. Some buildings have provisions for lightning protection in the form of air terminals connected to a ground counterpoise system. It is shown that fields and currents within these structures can be significantly high during a lightning strike. Time lapse video presentations were made showing the electric and magnetic field distributions on selected cross sections of the buildings during a simulated lightning strike.

Situational Lightning Climatologies for Central Florida: Phase IV: Central Florida Flow Regime Based Climatologies of Lightning Probabilities

NASA Technical Reports Server (NTRS)

Bauman, William H., III

2009-01-01

The threat of lightning is a daily concern during the warm season in Florida. Research has revealed distinct spatial and temporal distributions of lightning occurrence that are strongly influenced by large-scale atmospheric flow regimes. Previously, the Applied Meteorology Unit (AMU) calculated the gridded lightning climatologies based on seven flow regimes over Florida for 1-, 3- and 6-hr intervals in 5-, 10-, 20-, and 30-NM diameter range rings around the Shuttle Landing Facility (SLF) and eight other airfields in the National Weather Service in Melbourne (NWS MLB) county warning area (CWA). In this update to the work, the AMU recalculated the lightning climatologies for using individual lightning strike data to improve the accuracy of the climatologies. The AMU included all data regardless of flow regime as one of the stratifications, added monthly stratifications, added three years of data to the period of record and used modified flow regimes based work from the AMU's Objective Lightning Probability Forecast Tool, Phase II. The AMU made changes so the 5- and 10-NM radius range rings are consistent with the aviation forecast requirements at NWS MLB, while the 20- and 30-NM radius range rings at the SLF assist the Spaceflight Meteorology Group in making forecasts for weather Flight Rule violations during Shuttle landings. The AMU also updated the graphical user interface with the new data.

Evaluation of lightning accommodation systems for wind-driven turbine rotors

NASA Technical Reports Server (NTRS)

Bankaitis, H.

1982-01-01

Wind-driven turbine generators are being evaluated as an alternative source of electric energy. Areas of favorable location for the wind-driven turbines (high wind density) coincide with areas of high incidence of thunderstorm activity. These locations, coupled with the 30-m or larger diameter rotor blades, make the wind-driven turbine blades probable terminations for lightning strikes. Several candidate systems of lightning accommodation for composite-structural-material blades were designed and their effectiveness evaluated by submitting the systems to simulated lightning strikes. The test data were analyzed and system design were reviewed on the basis of the analysis.

Preliminary tests of vulnerability of typical aircraft electronics to lightning-induced voltages

NASA Technical Reports Server (NTRS)

Plumer, J. A.; Walko, L. C.

1974-01-01

Tests made on two pieces of typical aircraft electronics equipment to ascertain their vulnerability to simulated lightning-induced transient voltages representative of those which might occur in flight when the aircraft is struck by lightning were conducted. The test results demonstrated that such equipment can be interfered with or damaged by transient voltages as low as 21 volts peak. Greater voltages can cause failure of semiconductor components within the equipment. The results emphasize a need for establishment of coordinated system susceptibility and component vulnerability criteria to achieve lightning protection of aerospace electrical and electronic systems.

Towards Improving Satellite Tropospheric NO2 Retrieval Products: Impacts of the spatial resolution and lighting NOx production from the a priori chemical transport model

NASA Astrophysics Data System (ADS)

Smeltzer, C. D.; Wang, Y.; Zhao, C.; Boersma, F.

2009-12-01

Polar orbiting satellite retrievals of tropospheric nitrogen dioxide (NO2) columns are important to a variety of scientific applications. These NO2 retrievals rely on a priori profiles from chemical transport models and radiative transfer models to derive the vertical columns (VCs) from slant columns measurements. In this work, we compare the retrieval results using a priori profiles from a global model (TM4) and a higher resolution regional model (REAM) at the OMI overpass hour of 1330 local time, implementing the Dutch OMI NO2 (DOMINO) retrieval. We also compare the retrieval results using a priori profiles from REAM model simulations with and without lightning NOx (NO + NO2) production. A priori model resolution and lightning NOx production are both found to have large impact on satellite retrievals by altering the satellite sensitivity to a particular observation by shifting the NO2 vertical distribution interpreted by the radiation model. The retrieved tropospheric NO2 VCs may increase by 25-100% in urban regions and be reduced by 50% in rural regions if the a priori profiles from REAM simulations are used during the retrievals instead of the profiles from TM4 simulations. The a priori profiles with lightning NOx may result in a 25-50% reduction of the retrieved tropospheric NO2 VCs compared to the a priori profiles without lightning. As first priority, a priori vertical NO2 profiles from a chemical transport model with a high resolution, which can better simulate urban-rural NO2 gradients in the boundary layer and make use of observation-based parameterizations of lightning NOx production, should be first implemented to obtain more accurate NO2 retrievals over the United States, where NOx source regions are spatially separated and lightning NOx production is significant. Then as consequence of a priori NO2 profile variabilities resulting from lightning and model resolution dynamics, geostationary satellite, daylight observations would further promote the next step towards producing a more complete NO2 data product provided sufficient resolution of the observations. Both the corrected retrieval algorithm and the proposed next generation geostationary satellite observations would thus improve emission inventories, better validate model simulations, and advantageously optimize regional specific ozone control strategies.

Forecasting Lightning Threat using Cloud-Resolving Model Simulations

NASA Technical Reports Server (NTRS)

McCaul, Eugene W., Jr.; Goodman, Steven J.; LaCasse, Katherine M.; Cecil, Daniel J.

2008-01-01

Two new approaches are proposed and developed for making time and space dependent, quantitative short-term forecasts of lightning threat, and a blend of these approaches is devised that capitalizes on the strengths of each. The new methods are distinctive in that they are based entirely on the ice-phase hydrometeor fields generated by regional cloud-resolving numerical simulations, such as those produced by the WRF model. These methods are justified by established observational evidence linking aspects of the precipitating ice hydrometeor fields to total flash rates. The methods are straightforward and easy to implement, and offer an effective near-term alternative to the incorporation of complex and costly cloud electrification schemes into numerical models. One method is based on upward fluxes of precipitating ice hydrometeors in the mixed phase region at the-15 C level, while the second method is based on the vertically integrated amounts of ice hydrometeors in each model grid column. Each method can be calibrated by comparing domain-wide statistics of the peak values of simulated flash rate proxy fields against domain-wide peak total lightning flash rate density data from observations. Tests show that the first method is able to capture much of the temporal variability of the lightning threat, while the second method does a better job of depicting the areal coverage of the threat. Our blended solution is designed to retain most of the temporal sensitivity of the first method, while adding the improved spatial coverage of the second. Exploratory tests for selected North Alabama cases show that, because WRF can distinguish the general character of most convective events, our methods show promise as a means of generating quantitatively realistic fields of lightning threat. However, because the models tend to have more difficulty in predicting the instantaneous placement of storms, forecasts of the detailed location of the lightning threat based on single simulations can be in error. Although these model shortcomings presently limit the precision of lightning threat forecasts from individual runs of current generation models,the techniques proposed herein should continue to be applicable as newer and more accurate physically-based model versions, physical parameterizations, initialization techniques and ensembles of forecasts become available.

Analysis and Modeling of Intense Oceanic Lightning

NASA Astrophysics Data System (ADS)

Zoghzoghy, F. G.; Cohen, M.; Said, R.; Lehtinen, N. G.; Inan, U.

2014-12-01

Recent studies using lightning data from geo-location networks such as GLD360 suggest that lightning strokes are more intense over the ocean than over land, even though they are less common [Said et al. 2013]. We present an investigation of the physical differences between oceanic and land lightning. We have deployed a sensitive Low Frequency (1 MHz sampling rate) radio receiver system aboard the NOAA Ronald W. Brown research vessel and have collected thousands of lightning waveforms close to deep oceanic lightning. We analyze the captured waveforms, describe our modeling efforts, and summarize our findings. We model the ground wave (gw) portion of the lightning sferics using a numerical method built on top of the Stanford Full Wave Method (FWM) [Lehtinen and Inan 2008]. The gwFWM technique accounts for propagation over a curved Earth with finite conductivity, and is used to simulate an arbitrary current profile along the lightning channel. We conduct a sensitivity analysis and study the current profiles for land and for oceanic lightning. We find that the effect of ground conductivity is minimal, and that stronger oceanic radio intensity does not result from shorter current rise-time or from faster return stroke propagation speed.

A Simple Lightning Assimilation Technique For Improving Retrospective WRF Simulations

EPA Science Inventory

Convective rainfall is often a large source of error in retrospective modeling applications. In particular, positive rainfall biases commonly exist during summer months due to overactive convective parameterizations. In this study, lightning assimilation was applied in the Kain...

A simple lightning assimilation technique for improving retrospective WRF simulations.

EPA Science Inventory

Convective rainfall is often a large source of error in retrospective modeling applications. In particular, positive rainfall biases commonly exist during summer months due to overactive convective parameterizations. In this study, lightning assimilation was applied in the Kain-F...

Assimilation of lightning data by nudging tropospheric water vapor and applications to numerical forecasts of convective events

NASA Astrophysics Data System (ADS)

Dixon, Kenneth

A lightning data assimilation technique is developed for use with observations from the World Wide Lightning Location Network (WWLLN). The technique nudges the water vapor mixing ratio toward saturation within 10 km of a lightning observation. This technique is applied to deterministic forecasts of convective events on 29 June 2012, 17 November 2013, and 19 April 2011 as well as an ensemble forecast of the 29 June 2012 event using the Weather Research and Forecasting (WRF) model. Lightning data are assimilated over the first 3 hours of the forecasts, and the subsequent impact on forecast quality is evaluated. The nudged deterministic simulations for all events produce composite reflectivity fields that are closer to observations. For the ensemble forecasts of the 29 June 2012 event, the improvement in forecast quality from lightning assimilation is more subtle than for the deterministic forecasts, suggesting that the lightning assimilation may improve ensemble convective forecasts where conventional observations (e.g., aircraft, surface, radiosonde, satellite) are less dense or unavailable.

A three-dimensional total odd nitrogen (NO y ) simulation during SONEX using a stretched-grid chemical transport model

NASA Astrophysics Data System (ADS)

Allen, Dale; Pickering, Kenneth; Stenchikov, Georgiy; Thompson, Anne; Kondo, Yutaka

2000-02-01

The relative importance of various odd nitrogen (NOy) sources including lightning, aircraft, and surface emissions on upper tropospheric total odd nitrogen is illustrated as a first application of the three-dimensional Stretched-Grid University of Maryland/Goddard Chemical-Transport Model (SG-GCTM). The SG-GCTM has been developed to look at the effect of localized sources and/or small-scale mixing processes on the large-scale or global chemical balance. For this simulation the stretched grid was chosen so that its maximum resolution is located over eastern North America and the North Atlantic; a region that includes most of the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) flight paths. The SONEX period (October-November 1997) is simulated by driving the SG-GCTM with assimilated data from the Goddard Earth Observing System-Stratospheric Tracers of Atmospheric Transport Data Assimilation System (GEOS-STRAT DAS). A new algorithm is used to estimate the lightning flash rates needed to calculate NOy emission by lightning. This algorithm parameterizes the flash rate in terms of upper tropospheric convective mass flux. Model-calculated upper tropospheric NOy and NOy measurements from the NASA DC-8 aircraft are compared. Spatial variations in NOy were well captured especially with the stretched-grid run; however, model-calculated peaks due to "stratospheric" NOy are occasionally too large. The lightning algorithm reproduces the temporally and spatially averaged total flash rate accurately; however, the use of emissions from observed lightning flashes significantly improves the simulation on a few days, especially November 3, 1997, showing that significant uncertainty remains in parameterizing lightning in chemistry and transport models. Aircraft emissions contributed ˜15% of the upper tropospheric NOy averaged along SONEX flight paths within the North Atlantic Flight Corridor with the contribution exceeding 40% during portions of some flights.

Systems tunnel linear shaped charge lightning strike

NASA Technical Reports Server (NTRS)

Cook, M.

1989-01-01

Simulated lightning strike testing of the systems tunnel linear shaped charge (LSC) was performed at the Thiokol Lightning Test Complex in Wendover, Utah, on 23 Jun. 1989. The test article consisted of a 160-in. section of the LSC enclosed within a section of the systems tunnel. The systems tunnel was bonded to a section of a solid rocket motor case. All test article components were full scale. The systems tunnel cover of the test article was subjected to three discharges (each discharge was over a different grounding strap) from the high-current generator. The LSC did not detonate. All three grounding straps debonded and violently struck the LSC through the openings in the systems tunnel floor plates. The LSC copper surface was discolored around the areas of grounding strap impact, and arcing occurred at the LSC clamps and LSC ends. This test verified that the present flight configuration of the redesigned solid rocket motor systems tunnel, when subjected to simulated lightning strikes with peak current levels within 71 percent of the worst-case lightning strike condition of NSTS-07636, is adequate to prevent LSC ignition. It is therefore recommended that the design remain unchanged.

A Ground Flash Fraction Retrieval Algorithm for GLM

NASA Technical Reports Server (NTRS)

Koshak, William J.

2010-01-01

A Bayesian inversion method is introduced for retrieving the fraction of ground flashes in a set of N lightning observed by a satellite lightning imager (such as the Geostationary Lightning Mapper, GLM). An exponential model is applied as a physically reasonable constraint to describe the measured lightning optical parameter distributions. Population statistics (i.e., the mean and variance) are invoked to add additional constraints to the retrieval process. The Maximum A Posteriori (MAP) solution is employed. The approach is tested by performing simulated retrievals, and retrieval error statistics are provided. The approach is feasible for N greater than 2000, and retrieval errors decrease as N is increased.

Elves and associated electron density changes due to cloud-to-ground and in-cloud lightning discharges

NASA Astrophysics Data System (ADS)

Marshall, R. A.; Inan, U. S.; Glukhov, V. S.

2010-04-01

A 3-D finite difference time domain model is used to simulate the lightning electromagnetic pulse (EMP) and its interaction with the lower ionosphere. Results agree with the frequently observed, doughnut-shaped optical signature of elves but show that the structure exhibits asymmetry due to the presence of Earth's ambient magnetic field. Furthermore, in-cloud (horizontal) lightning channels produce observable optical emissions without the doughnut shape and, in fact, produce a much stronger optical output for the same channel current. Electron density perturbations associated with elves are also calculated, with contributions from attachment and ionization. Results presented as a function of parameters such as magnetic field direction, dipole current orientation, altitude and amplitude, and ambient ionospheric density profile demonstrate the highly nonlinear nature of the EMP-ionosphere interaction. Ionospheric effects of a sequence of in-cloud discharges are calculated, simulating a burst of in-cloud lightning activity and resulting in large density changes in the overlying ionosphere.

On the field-to-current conversion factors for large bipolar lightning discharge events in winter thunderstorms in Japan

NASA Astrophysics Data System (ADS)

Chen, Long; Zhang, Qilin; Hou, Wenhao; Tao, Yulang

2015-07-01

In this paper we have simulated the far-field waveform characteristic of large bipolar events (LBEs) occurred in winter thunderstorms in Japan and compared the field-to-current conversion factors (FCCFs) of LBEs with that of the lightning cloud-to-ground (CG) return stroke (RS) in summer thunderstorm. As for the physical process of LBEs, Wu et al. (2014) considered that LBEs may be very similar to the typical lightning RS (RS-like process) or caused by an initial continuous current pulse (ICC-like process) in upward lightning flashes. We assume that the lightning channel length of LBEs ranges from 500 m to 1000 m, and the height of tall object struck by LBEs is from 100 m to 300 m. By using the bouncing wave model, we found that only when the injected current waveform of LBEs is characterized with a symmetric Gaussian pulse, the simulated far-field waveform of LBEs both for RS-like process and ICC-like process is similar to that observed by Wu et al. (2014). For striking tall objects with heights from 100 m and 300 m, the FCCFs of LBEs are positively correlated with its channel length and derivatives of injected current waveform, and the FCCF for RS-like process is about similar to that for ICC-like process. However, the FCCFs of LBEs are very different from lightning RS in summer thunderstorm; that is to say, the FCCFs developed for the well-known lightning RS in summer thunderstorm are not suitable for LBEs.

Situational Lightning Climatologies for Central Florida: Phase IV

NASA Technical Reports Server (NTRS)

Bauman, William H., III

2009-01-01

The threat of lightning is a daily concern during the warm season in Florida. Research has revealed distinct spatial and temporal distributions of lightning occurrence that are strongly influenced by large-scale atmospheric flow regimes. Previously, the Applied Meteorology Unit (AMU) calculated the gridded lightning climatologies based on seven flow regimes over Florida for 1-, 3- and 6-hr intervals in 5-, 10-,20-, and 30-NM diameter range rings around the Shuttle Landing Facility (SLF) and eight other airfields in the National Weather Service in Melbourne (NWS MLB) county warning area (CWA). In this update to the work, the AMU recalculated the lightning climatologies for using individual lightning strike data to improve the accuracy of the climatologies. The AMU included all data regardless of flow regime as one of the stratifications, added monthly stratifications, added three years of data to the period of record and used modified flow regimes based work from the AMU's Objective Lightning Probability Forecast Tool, Phase II. The AMU made changes so the 5- and 10-NM radius range rings are consistent with the aviation forecast requirements at NWS MLB, while the 20- and 30-NM radius range rings at the SLF assist the Spaceflight Meteorology Group in making forecasts for weather Flight Rule violations during Shuttle landings. The AMU also updated the graphical user interface with the new data.

NOy and O3 in the Asian Monsoon Anticyclone: Uncertainties associated with the Convection and Lightning in a Global Model

NASA Astrophysics Data System (ADS)

Pozzer, A.; Ojha, N.; Tost, H.; Joeckel, P.; Fischer, H.; Ziereis, H.; Zahn, A.; Tomsche, L.; Lelieveld, J.

2017-12-01

The impacts of Asian monsoon on the tropospheric chemistry are difficult to simulate in numerical models due to the lack of accurate emission inventories over the Asian region and the strong influence of parameterized processes such as convection and lightning. Further, the lack of observational data over the region during the monsoon period reduce drastically the capability to evaluate numerical models. Here, we combine simulations using the global EMAC (ECHAM5/MESSy2 Atmospheric Chemistry) model with the observational dataset based on the OMO campaign (July-August 2015) to study the tropospheric composition in the Asian monsoon anticyclone. The results of the simulations capture the C-shape of the CO vertical profiles, typically observed during the summer monsoon. The observed spatio-temporal variations in O3, CO, and NOy are reproduced by EMAC, with a better correlation in the upper troposphere (UT). However, the model overestimates NOy and O3 mixing ratios in the anticyclone by 25% and 35%, respectively. A series of numerical experiments showed the strong lightning emissions in the model as the source of this overestimation, with the anthropogenic NOx sources (in Asia) and global soil emissions having lower impact in the UT. A reduction of the lightning NOx emission by 50% leads to a better agreement between the model and OMO observations of NOy and O3. The uncertainties in the lightning emissions are found to considerably influence the OH distribution in the UT over India and downwind. The study reveals existing uncertainties in the estimations of monsoon impact on the tropospheric composition, and highlights the need to constrain numerical simulations with state-of-the-art observations for deriving the budget of trace species of climatic relevance.

Pulse generator with intermediate inductive storage as a lightning simulator

NASA Astrophysics Data System (ADS)

Kovalchuk, B. M.; Kharlov, A. V.; Zherlytsyn, A. A.; Kumpyak, E. V.; Tsoy, N. V.

2016-06-01

Compact transportable generators are required for simulating a lightning current pulse for electrical apparatus testing. A bi-exponential current pulse has to be formed by such a generator (with a current rise time of about two orders of magnitude faster than the damping time). The objective of this study was to develop and investigate a compact pulse generator with intermediate inductive storage and a fuse opening switch as a simulator of lightning discharge. A Marx generator (six stages) with a capacitance of 1 μF and an output voltage of 240 kV was employed as primary storage. In each of the stages, two IK-50/3 (50 kV, 3 μF) capacitors are connected in parallel. The generator inductance is 2 μH. A test bed for the investigations was assembled with this generator. The generator operates without SF6 and without oil in atmospheric air, which is very important in practice. Straight copper wires with adjustable lengths and diameters were used for the electro-explosive opening switch. Tests were made with active-inductive loads (up to 0.1 Ω and up to 6.3 μH). The current rise time is lower than 1200 ns, and the damping time can be varied from 35 to 125 μs, following the definition of standard lightning current pulse in the IEC standard. Moreover, 1D MHD calculations of the fuse explosion were carried out self-consistently with the electric circuit equations, in order to calculate more accurately the load pulse parameters. The calculations agree fairly well with the tests. On the basis of the obtained results, the design of a transportable generator was developed for a lightning simulator with current of 50 kA and a pulse shape corresponding to the IEEE standard.

Characteristics of VLF/LF Sferics from Elve-producing Lightning Discharges

NASA Astrophysics Data System (ADS)

Blaes, P.; Zoghzoghy, F. G.; Marshall, R. A.

2013-12-01

Lightning return strokes radiate an electromagnetic pulse (EMP) which interacts with the D-region ionosphere; the largest EMPs produce new ionization, heating, and optical emissions known as elves. Elves are at least six times more common than sprites and other transient luminous events. Though the probability that a lightning return stroke will produce an elve is correlated with the return stroke peak current, many large peak current strokes do not produce visible elves. Apart from the lightning peak current, elve production may depend on the return stroke speed, lightning altitude, and ionospheric conditions. In this work we investigate the detailed structure of lightning that gives rise to elves by analyzing the characteristics of VLF/LF lightning sferics in conjunction with optical elve observations. Lightning sferics were observed using an array of six VLF/LF receivers (1 MHz sample-rate) in Oklahoma, and elves were observed using two high-speed photometers pointed over the Oklahoma region: one located at Langmuir Laboratory, NM and the other at McDonald Observatory, TX. Hundreds of elves with coincident LF sferics were observed during the summer months of 2013. We present data comparing the characteristics of elve-producing and non-elve producing lightning as measured by LF sferics. In addition, we compare these sferic and elve observations with FDTD simulations to determine key properties of elve-producing lightning.

Simulating statistics of lightning-induced and man made fires

NASA Astrophysics Data System (ADS)

Krenn, R.; Hergarten, S.

2009-04-01

The frequency-area distributions of forest fires show power-law behavior with scaling exponents α in a quite narrow range, relating wildfire research to the theoretical framework of self-organized criticality. Examples of self-organized critical behavior can be found in computer simulations of simple cellular automata. The established self-organized critical Drossel-Schwabl forest fire model (DS-FFM) is one of the most widespread models in this context. Despite its qualitative agreement with event-size statistics from nature, its applicability is still questioned. Apart from general concerns that the DS-FFM apparently oversimplifies the complex nature of forest dynamics, it significantly overestimates the frequency of large fires. We present a straightforward modification of the model rules that increases the scaling exponent α by approximately 1•3 and brings the simulated event-size statistics close to those observed in nature. In addition, combined simulations of both the original and the modified model predict a dependence of the overall distribution on the ratio of lightning induced and man made fires as well as a difference between their respective event-size statistics. The increase of the scaling exponent with decreasing lightning probability as well as the splitting of the partial distributions are confirmed by the analysis of the Canadian Large Fire Database. As a consequence, lightning induced and man made forest fires cannot be treated separately in wildfire modeling, hazard assessment and forest management.

Electromagnetic emission from terrestrial lightning in the 0.1-30 MHz frequency range

NASA Astrophysics Data System (ADS)

Karashtin, A. N.; Gurevich, A. V.

Results of measurements carried out at SURA facility of Radiophisical Research Institute and at Tien-Shan Mountain Scientific Station of Lebedev Physical Institute using specially designed installations for short electromagnetic pulse observation in the frequency range from 0.1 to 30 MHz are presented. Specific attention is paid to initial stage of the lightning discharge. It is shown that lightning can be initiated by extensive atmospheric showers caused by high energy cosmic ray particles. Analysis of emission of few thousand lightning discharges showed that • Short wave radio emission of lightning consists of a series of short pulses with duration from less than 100 nanoseconds to several microseconds separated well longer gaps. • Background noise between lightning discharges is not differ from one observed without thunderstorm activity (at given sensitivity). Usually it is the same between lightning pulses at least at the initial stage. • Each lightning discharge radio emission starts with a number of very short (less than 100 nanoseconds at 0.7 level) bi-polar pulses. Gaps between initial pulses vary from several microseconds to few hundreds of microseconds. No radio emission was observed before the first pulse during at least 500 milliseconds. Both positive and negative polarity of the first pulses occur in approximately equal proportion in different lightning discharges while the polarity was the same in any individual lightning. • First pulse amplitude, width and waveform are consistent with predicted by the theory of combined action of runaway breakdown and extensive atmospheric shower caused by cosmic ray particle of 1016 eV energy. Lightning discharges at other planets can be initiated by cosmic ray particles as well. This work was partly supported by ISTC grant # 2236p. The work of one of the authors (A. N. Karashtin) was also partly supported by INTAS grant # 03-51-5727.

KSC-04PD-1317

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility, Jay Feaster, general manager of the National Hockey League 2004 Champions Tampa Bay Lightning, displays the Stanley Cup. At right is KSC Deputy Director Woodrow Whitlow. The cup was also briefly available for viewing by employees in the KSC Training Auditorium. Feaster brought the cup to KSC while on a tour. The Stanley Cup weighs 35 pounds and is more than 100 years old. The Lightning will be added to the cup in September.

Laboratory-Scale Evidence for Lightning-Mediated Gene Transfer in Soil

PubMed Central

Demanèche, Sandrine; Bertolla, Franck; Buret, François; Nalin, Renaud; Sailland, Alain; Auriol, Philippe; Vogel, Timothy M.; Simonet, Pascal

2001-01-01

Electrical fields and current can permeabilize bacterial membranes, allowing for the penetration of naked DNA. Given that the environment is subjected to regular thunderstorms and lightning discharges that induce enormous electrical perturbations, the possibility of natural electrotransformation of bacteria was investigated. We demonstrated with soil microcosm experiments that the transformation of added bacteria could be increased locally via lightning-mediated current injection. The incorporation of three genes coding for antibiotic resistance (plasmid pBR328) into the Escherichia coli strain DH10B recipient previously added to soil was observed only after the soil had been subjected to laboratory-scale lightning. Laboratory-scale lightning had an electrical field gradient (700 versus 600 kV m−1) and current density (2.5 versus 12.6 kA m−2) similar to those of full-scale lightning. Controls handled identically except for not being subjected to lightning produced no detectable antibiotic-resistant clones. In addition, simulated storm cloud electrical fields (in the absence of current) did not produce detectable clones (transformation detection limit, 10−9). Natural electrotransformation might be a mechanism involved in bacterial evolution. PMID:11472916

Laboratory simulations of volcanic ash charging and conditions for volcanic lightning on Venus

NASA Astrophysics Data System (ADS)

Airey, Martin; Warriner-Bacon, Elliot; Aplin, Karen

2017-04-01

Lightning may be important in the emergence of life on Earth and elsewhere, as significant chemical reactions occur in the superheated region around the lightning channel. This, combined with the availability of phosphates in volcanic clouds, suggests that volcanic lightning could have been the catalyst for the formation of biological compounds on the early Earth [1]. In addition to meteorological lightning, volcanic activity also generates electrical discharges within charged ash plumes, which can be a significant contributor to atmospheric electricity on geologically active planets. The physical properties of other planetary atmospheres, such as that of Venus, have an effect on the processes that lead to the generation of volcanic lightning. Volcanism is known to have occurred on Venus in the past, and recent observations made by ESA's Venus Express satellite have provided evidence for currently active volcanism [2-4], and lightning discharges [e.g. 5]. Venusian lightning could potentially be volcanic in origin, since no meteorological mechanisms are known to separate charge effectively in its clouds [6]. The hunt for further evidence for lightning at Venus is ongoing, for example by means of the Lightning and Airglow Camera (LAC) [7] on Akatsuki, the current JAXA mission at Venus. Our laboratory experiments simulate ash generation and measure electrical charging of the ash under typical atmospheric conditions on Earth and Venus. The study uses a 1 litre chamber, which, when pressurised and heated, can simulate the high-pressure, high-temperature, carbon dioxide-dominated atmosphere of Venus at 10 km altitude ( 5 MPa, 650 K). A key finding of previous work [8] is that ash plume-forming eruptions are more likely to occur at higher altitudes such as these on Venus. The chamber contains temperature/pressure monitoring and logging equipment, a rock collision apparatus (based on [9]) to generate the charged rock fragments, and charge measurement electrodes connected to a high-precision electrometer. The separate effects of varying the atmospheric composition, temperature, and pressure on the charges attained and the relationship between particle size and charge polarity will be addressed, and the implications discussed. The key questions considered here are: (a) is volcanic activity a feasible mechanism for lightning generation on Venus, (b) how do the extreme environmental conditions on Venus affect the mechanisms required to generate lightning, (c) what are the implications for volcanic lightning's role in the emergence of life on other planets? [1] Navarro-Gonzalez, R. and Segura, A., (2001) Volcanic lightning and the availability of reactive nitrogen and phosphorus for chemical evolution. [2] Marcq, E., et al. (2012) Nature Geoscience, 1-4 [3] Shalygin, E.V., et al. (2015) Geophys. Res. Lett., 42 [4] Smrekar, S.E., et al. (2010) Science, 328, 5978, 605-608 [5] Russell, C.T., et al. (2008) Journal of Geophysical Research-Planets, 113 [6] Aplin, K.L. and Fischer, G. (In press) Weather, (preprint at https://arxiv.org/abs/1606.03285) [7] Takahashi, Y., et al. (2008) Space Sci. Rev., 137, 1-4, 317-334 [8] Airey, M.W., et al. (2015) Planetary and Space Science, 113-114, 33-48 [9] James, M.R., et al. (2000) Journal of Geophysical Research-Solid Earth, 105, B7, 16641-16649

Modelling Digital Thunder

ERIC Educational Resources Information Center

Blanco, Francesco; La Rocca, Paola; Petta, Catia; Riggi, Francesco

2009-01-01

An educational model simulation of the sound produced by lightning in the sky has been employed to demonstrate realistic signatures of thunder and its connection to the particular structure of the lightning channel. Algorithms used in the past have been revisited and implemented, making use of current computer techniques. The basic properties of…

Isolation of Lightning-Competent Soil Bacteria

PubMed Central

Cérémonie, Hélène; Buret, François; Simonet, Pascal; Vogel, Timothy M.

2004-01-01

Artificial transformation is typically performed in the laboratory by using either a chemical (CaCl2) or an electrical (electroporation) method. However, laboratory-scale lightning has been shown recently to electrotransform Escherichia coli strain DH10B in soil. In this paper, we report on the isolation of two “lightning-competent” soil bacteria after direct electroporation of the Nycodenz bacterial ring extracted from prairie soil in the presence of the pBHCRec plasmid (Tcr, Spr, Smr). The electrotransformability of the isolated bacteria was measured both in vitro (by electroporation cuvette) and in situ (by lightning in soil microcosm) and then compared to those of E. coli DH10B and Pseudomonas fluorescens C7R12. The electrotransformation frequencies measured reached 10−3 to 10−4 by electroporation and 10−4 to 10−5 by simulated lightning, while no transformation was observed in the absence of electrical current. Two of the isolated lightning-competent soil bacteria were identified as Pseudomonas sp. strains. PMID:15466589

Experience in the management of disused lightning rods containing 241Am in a research institute in Brazil.

PubMed

Vicente, Roberto; Potiens, Ademar; Sakata, Solange; Dellamano, José

2013-11-01

Radioactive lightning rods (RLR) were manufactured and installed in Brazil for almost two decades, before they were prohibited in 1989. Structures protected by this type of lightning preventers included residential buildings, schools, commercial and industrial facilities, among others. It is estimated that about 3.4 TBq of 241Am were used by manufacturers, and a total of 75,000 pieces with a mean activity of about 46 MBq were in the market. While only a fraction of the total has been recovered, the almost twenty thousand pieces already collected at the Nuclear and Energy Research Institute (IPEN) had their sources successfully separated from the remaining recyclable metal scrap and are now encapsulated in lead containers for final disposal.

Application of surface electrical discharges to the study of lightning strikes on aircraft

NASA Technical Reports Server (NTRS)

Boulay, J. L.; Larigaldie, S.

1991-01-01

Considered here is the characterization of surface discharges which provide a facility complementary to that of artificially triggered lightning. General characteristics of a simplified surface discharge, including current waveforms and the constitution of a surface discharge are outlined, and the application of this approach to the study of aircraft lightning strikes is considered. Representations of leader-streamer and return-stroke phases are discussed, and the application to the two-dimensional discharge phase is covered. It is noted that the fact that the initiation times of surface discharges could be controlled, and the path followed by the discharge channels could be predetermined, indicates that it is possible to produce a highly dedicated high performance instrumentation system.

A transportable 50 kA dual mode lightning simulator

NASA Technical Reports Server (NTRS)

Salisbury, K.; Lloyd, S.; Chen, Y. G.

1991-01-01

A transportable lightning simulator was designed, built and tested, which is capable of delivering more than 50 kA to an 8 micro-H test object. The simulator was designed to be a versatile device in the lightning laboratory while meeting the requirements of MIL-STD-1757A for component E current waveforms. The system is capable of operating in either a ringing mode with a Q greater than 5 and a nominal frequency of 160 kHz, or a unipolar mode with no hardware configuration changes. The ringing mode is obtained by the LCR series circuit formed by the pulse generator and test object. The unipolar mode is obtained by closing an electrically triggered crowbar switch at peak current. The simulator exceeds the peak current requirement and rate of rise requirements for MIL-STD-1757A in both the ringing and unipolar modes. The pulse half width in the unipolar mode is in excess of 50 microsec and the action is in excess of 10(exp 5) A(exp 2)s. The design, component values, and test results are presented.

KSC-04PD-1318

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility, Jay Feaster, general manager of the National Hockey League 2004 Champions Tampa Bay Lightning, sits next to the Stanley Cup in front of the open hatch into Discovery. The cup was also briefly available for viewing by employees in the KSC Training Auditorium. Feaster brought the cup to KSC while on a tour. The Stanley Cup weighs 35 pounds and is more than 100 years old. The Lightning will be added to the cup in September.

KSC-04PD-1314

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Jay Feaster, general manager of the National Hockey League 2004 Champions Tampa Bay Lightning, stands next to the Stanley Cup, which he brought to KSC while on a tour. The cup stands next to the orbiter Discovery in the Orbiter Processing Facility. The cup was also briefly available for viewing by employees in the KSC Training Auditorium. The Stanley Cup weighs 35 pounds and is more than 100 years old. The Lightning will be added to the cup in September.

KSC-04PD-1315

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Jack Legere, NASA Quality Assurance specialist for the Shuttle Program, displays the Stanley Cup to employees in the Orbiter Processing Facility. Behind him is Discovery. Jay Feaster, general manager of the National Hockey League 2004 Champions Tampa Bay Lightning, brought the cup to KSC while on a tour. The cup was also briefly available for viewing by employees in the KSC Training Auditorium. The Stanley Cup weighs 35 pounds and is more than 100 years old. The Lightning will be added to the cup in September.

Do cosmic ray air showers initiate lightning?: A statistical analysis of cosmic ray air showers and lightning mapping array data

NASA Astrophysics Data System (ADS)

Hare, B. M.; Dwyer, J. R.; Winner, L. H.; Uman, M. A.; Jordan, D. M.; Kotovsky, D. A.; Caicedo, J. A.; Wilkes, R. A.; Carvalho, F. L.; Pilkey, J. T.; Ngin, T. K.; Gamerota, W. R.; Rassoul, H. K.

2017-08-01

It has been argued in the technical literature, and widely reported in the popular press, that cosmic ray air showers (CRASs) can initiate lightning via a mechanism known as relativistic runaway electron avalanche (RREA), where large numbers of high-energy and low-energy electrons can, somehow, cause the local atmosphere in a thundercloud to transition to a conducting state. In response to this claim, other researchers have published simulations showing that the electron density produced by RREA is far too small to be able to affect the conductivity in the cloud sufficiently to initiate lightning. In this paper, we compare 74 days of cosmic ray air shower data collected in north central Florida during 2013-2015, the recorded CRASs having primary energies on the order of 1016 eV to 1018 eV and zenith angles less than 38°, with Lightning Mapping Array (LMA) data, and we show that there is no evidence that the detected cosmic ray air showers initiated lightning. Furthermore, we show that the average probability of any of our detected cosmic ray air showers to initiate a lightning flash can be no more than 5%. If all lightning flashes were initiated by cosmic ray air showers, then about 1.6% of detected CRASs would initiate lightning; therefore, we do not have enough data to exclude the possibility that lightning flashes could be initiated by cosmic ray air showers.

Terrestrial gamma-ray flash production by lightning

NASA Astrophysics Data System (ADS)

Carlson, Brant E.

Terrestrial gamma-ray flashes (TGFs) are brief flashes of gamma-rays originating in the Earth's atmosphere and observed by satellites. First observed in 1994 by the Burst And Transient Source Experiment on board the Compton Gamma-Ray Observatory, TGFs consist of one or more ˜1 ms pulses of gamma-rays with a total fluence of ˜1/cm2, typically observed when the satellite is near active thunderstorms. TGFs have subsequently been observed by other satellites to have a very hard spectrum (harder than dN/d E ∝ 1/ E ) that extends from below 25 keV to above 20 MeV. When good lightning data exists, TGFs are closely associated with measurable lightning discharge. Such discharges are typically observed to occur within 300 km of the sub-satellite point and within several milliseconds of the TGF observation. The production of these intense energetic bursts of photons is the puzzle addressed herein. The presence of high-energy photons implies a source of bremsstrahlung, while bremsstrahlung implies a source of energetic electrons. As TGFs are associated with lightning, fields produced by lightning are naturally suggested to accelerate these electrons. Initial ideas about TGF production involved electric fields high above thunderstorms as suggested by upper atmospheric lightning research and the extreme energies required for lower-altitude sources. These fields, produced either quasi-statically by charges in the cloud and ionosphere or dynamically by radiation from lightning strokes, can indeed drive TGF production, but the requirements on the source lightning are too extreme and therefore not common enough to account for all existing observations. In this work, studies of satellite data, the physics of energetic electron and photon production, and consideration of lightning physics motivate a new mechanism for TGF production by lightning current pulses. This mechanism is then developed and used to make testable predictions. TGF data from satellite observations are compared to the results of Monte Carlo simulations of the physics of energetic photon production and propagation in air. These comparisons are used to constrain the TGF source altitude, energy, and directional distribution, and indicate a broadly-beamed low-altitude source inconsistent with production far above thunderstorms as previously suggested. The details of energetic electron production by electric fields in air are then examined. In particular, the source of initial high-energy electrons that are accelerated and undergo avalanche multiplication to produce bremsstrahlung is studied and the properties of these initial seed particles as produced by cosmic rays are determined. The number of seed particles available indicates either extremely large amplification of the number of seed particles or an alternate source of seeds. The low-altitude photon source and alternate source of seed particles required by these studies suggest a production mechanism closely-associated with lightning. A survey of lightning physics in the context of TGF emission indicates that current pulses along lightning channels may trigger TGF production by both producing strong electric fields and a large population of candidate seed electrons. The constraints on lightning physics, thunderstorm physics, and TGF physics all allow production by this mechanism. A computational model of this mechanism is then presented on the basis of a method of moments simulation of charge and current on a lightning channel. Calculation of the nearby electric fields then drives Monte Carlo simulations of energetic electron dynamics which determine the properties of the resulting bremsstrahlung. The results of this model compare quite well with satellite observations of TGFs subject to requirements on the ambient electric field and the current pulse magnitude and duration. The model makes quantitative predictions about the TGF source altitude, directional distribution, and lightning association that are in overall agreement with existing TGF observations and may be tested in more detail in future experiments.

Performance Study of Earth Networks Total Lightning Network using Rocket-Triggered Lightning Data in 2014

NASA Astrophysics Data System (ADS)

Heckman, S.

2015-12-01

Modern lightning locating systems (LLS) provide real-time monitoring and early warning of lightningactivities. In addition, LLS provide valuable data for statistical analysis in lightning research. It isimportant to know the performance of such LLS. In the present study, the performance of the EarthNetworks Total Lightning Network (ENTLN) is studied using rocket-triggered lightning data acquired atthe International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida.In the present study, 18 flashes triggered at ICLRT in 2014 were analyzed and they comprise of 78negative cloud-to-ground return strokes. The geometric mean, median, minimum, and maximum for thepeak currents of the 78 return strokes are 13.4 kA, 13.6 kA, 3.7 kA, and 38.4 kA, respectively. The peakcurrents represent typical subsequent return strokes in natural cloud-to-ground lightning.Earth Networks has developed a new data processor to improve the performance of their network. Inthis study, results are presented for the ENTLN data using the old processor (originally reported in 2014)and the ENTLN data simulated using the new processor. The flash detection efficiency, stroke detectionefficiency, percentage of misclassification, median location error, median peak current estimation error,and median absolute peak current estimation error for the originally reported data from old processorare 100%, 94%, 49%, 271 m, 5%, and 13%, respectively, and those for the simulated data using the newprocessor are 100%, 99%, 9%, 280 m, 11%, and 15%, respectively. The use of new processor resulted inhigher stroke detection efficiency and lower percentage of misclassification. It is worth noting that theslight differences in median location error, median peak current estimation error, and median absolutepeak current estimation error for the two processors are due to the fact that the new processordetected more number of return strokes than the old processor.

Error Analyses of the North Alabama Lightning Mapping Array (LMA)

NASA Technical Reports Server (NTRS)

Koshak, W. J.; Solokiewicz, R. J.; Blakeslee, R. J.; Goodman, S. J.; Christian, H. J.; Hall, J. M.; Bailey, J. C.; Krider, E. P.; Bateman, M. G.; Boccippio, D. J.

2003-01-01

Two approaches are used to characterize how accurately the North Alabama Lightning Mapping Array (LMA) is able to locate lightning VHF sources in space and in time. The first method uses a Monte Carlo computer simulation to estimate source retrieval errors. The simulation applies a VHF source retrieval algorithm that was recently developed at the NASA-MSFC and that is similar, but not identical to, the standard New Mexico Tech retrieval algorithm. The second method uses a purely theoretical technique (i.e., chi-squared Curvature Matrix theory) to estimate retrieval errors. Both methods assume that the LMA system has an overall rms timing error of 50ns, but all other possible errors (e.g., multiple sources per retrieval attempt) are neglected. The detailed spatial distributions of retrieval errors are provided. Given that the two methods are completely independent of one another, it is shown that they provide remarkably similar results, except that the chi-squared theory produces larger altitude error estimates than the (more realistic) Monte Carlo simulation.

A Method for Retrieving Ground Flash Fraction from Satellite Lightning Imager Data

NASA Technical Reports Server (NTRS)

Koshak, William J.

2009-01-01

A general theory for retrieving the fraction of ground flashes in N lightning observed by a satellite-based lightning imager is provided. An "exponential model" is applied as a physically reasonable constraint to describe the measured optical parameter distributions, and population statistics (i.e., mean, variance) are invoked to add additional constraints to the retrieval process. The retrieval itself is expressed in terms of a Bayesian inference, and the Maximum A Posteriori (MAP) solution is obtained. The approach is tested by performing simulated retrievals, and retrieval error statistics are provided. The ability to retrieve ground flash fraction has important benefits to the atmospheric chemistry community. For example, using the method to partition the existing satellite global lightning climatology into separate ground and cloud flash climatologies will improve estimates of lightning nitrogen oxides (NOx) production; this in turn will improve both regional air quality and global chemistry/climate model predictions.

Acoustic localization of triggered lightning

NASA Astrophysics Data System (ADS)

Arechiga, Rene O.; Johnson, Jeffrey B.; Edens, Harald E.; Thomas, Ronald J.; Rison, William

2011-05-01

We use acoustic (3.3-500 Hz) arrays to locate local (<20 km) thunder produced by triggered lightning in the Magdalena Mountains of central New Mexico. The locations of the thunder sources are determined by the array back azimuth and the elapsed time since discharge of the lightning flash. We compare the acoustic source locations with those obtained by the Lightning Mapping Array (LMA) from Langmuir Laboratory, which is capable of accurately locating the lightning channels. To estimate the location accuracy of the acoustic array we performed Monte Carlo simulations and measured the distance (nearest neighbors) between acoustic and LMA sources. For close sources (<5 km) the mean nearest-neighbors distance was 185 m compared to 100 m predicted by the Monte Carlo analysis. For far distances (>6 km) the error increases to 800 m for the nearest neighbors and 650 m for the Monte Carlo analysis. This work shows that thunder sources can be accurately located using acoustic signals.

Lightning Strike Simula tion for Studying Southern Pine Bark and Engraver Beetle Attacks

Treesearch

Mitchel C. Miller

1983-01-01

Endemic populations of the southern pine beetle (Dendroctonus frontalis Zimm.) and Ips spp. attacked loblolly pines (Pinus taeda L.) on which lightning strikes were simulated with detonating cord in the field. Southern pine beetles were reared in successive generations in these trees from fall 1981 through spring 1982; only

NOSL experiment support

NASA Technical Reports Server (NTRS)

Brook, M.

1986-01-01

An optical lightning detector was constructed and flown, along with Vinton cameras and a Fairchild Line Scan Spectrometer, on a U-2 during the summer of 1979. The U-2 lightning data was obtained in daylight, and was supplemented with ground truth taken at Langmuir Laboratory. Simulations were prepared as required to establish experiment operating procedures and science training for the astronauts who would operate the Night/Day Optical Survey of Thunderstorm Lightning (NOSL) equipment during the STS-2 NOSL experiment on the Space Shuttle. Data was analyzed and papers were prepared for publication.

International Aerospace and Ground Conference on Lightning and Static Electricity (ICOLSE) (10th) and the Congres International Aeronautiq (17th) Held in Paris (France) on 10-13 June 1985

DTIC Science & Technology

1985-06-13

reelles de foudroiement et comparer ensuite les reponses obtenues ä celles issues de la simulation au sol, qui laisse subsister un doute quant a sa...but not be limited to, the follow- ing I tens: a) Management control b) Lightning zone identification c) Lightning coirpo.ient identification d...critical roles in functions such as stores management and fly-by-wire systems. Therefore, a great concern arises for preventing upset of these

Credit PSR. This view shows the south and east facades ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Credit PSR. This view shows the south and east facades of this concrete block facility as seen when looking northwest (320°). Note the outdoor emergency shower; the roof has lightning rods installed at corners - Jet Propulsion Laboratory Edwards Facility, Oxidizer Weigh & Storage Building, Edwards Air Force Base, Boron, Kern County, CA

Evaluation of Lightning Induced Effects in a Graphite Composite Fairing Structure

NASA Technical Reports Server (NTRS)

Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

2011-01-01

Defining the electromagnetic environment inside a graphite composite fairing due to near-by lightning strikes is of interest to spacecraft developers. This effort develops a transmission-line-matrix (TLM) model with a CST Microstripes to examine induced voltages. on interior wire loops in a composite fairing due to a simulated near-by lightning strike. A physical vehicle-like composite fairing test fixture is constructed to anchor a TLM model in the time domain and a FEKO method of moments model in the frequency domain. Results show that a typical graphite composite fairing provides adequate shielding resulting in a significant reduction in induced voltages on high impedance circuits despite minimal attenuation of peak magnetic fields propagating through space in near-by lightning strike conditions.

Lightning Nitrogen Oxides (LNOx) Vertical Profile Quantification and 10 Year Trend Analysis using Ozone Monitoring Instrument (OMI) Satellite Measurements, Air Quality Station (AQS) Surface Measurements, The National Lightning Detection Network (NLDN), and Simulated by Cloud Resolving Chemical Transport Model (REAM Cloud)

NASA Astrophysics Data System (ADS)

Smeltzer, C. D.; Wang, Y.; Koshak, W. J.

2014-12-01

Vertical profiles and emission lifetimes of lightning nitrogen oxides (LNOx) are derived using the Ozone Monitoring Instrument (OMI). Approximately 200 million flashes, over a 10 year climate period, from the United States National Lighting Detection Network (NLDN), are aggregated with OMI cloud top height to determine the vertical LNOx structure. LNOx lifetime is determined as function of LNOx signal in a 36 kilometer vertical column from the time of the last known flash to depletion of the LNOx signal. Environmental Protection Agency (EPA) Air Quality Station (AQS) surface data further support these results by demonstrating as much as a 200% increase in surface level NO2 during strong thunderstorm events and a lag as long as 5 to 8 hours from the lightning event to the peak surface event, indicating a evolutional process. Analysis of cloud resolving chemical transport model (REAM Cloud) demonstrates that C-shaped LNOx profiles, which agree with OMI vertical profile observations, evolve due to micro-scale convective meteorology given inverted C-shaped LNOx emission profiles as determined from lightning radio telemetry. It is shown, both in simulations and in observations, that the extent to which the LNOx vertical distribution is C-shaped and the lifetime of LNOx is proportional to the shear-strength of the thunderstorm. Micro-scale convective meteorology is not adequately parameterized in global scale and regional scale chemical transport models (CTM). Therefore, these larger scale CTMs ought to use a C-shape emissions profile to best reproduce observations until convective parameterizations are updated. These findings are used to simulate decadal LNOx and lightning ozone climatology over the Continental United States (CONUS) from 2004-2014.

The Ground Flash Fraction Retrieval Algorithm Employing Differential Evolution: Simulations and Applications

NASA Technical Reports Server (NTRS)

Koshak, William; Solakiewicz, Richard

2012-01-01

The ability to estimate the fraction of ground flashes in a set of flashes observed by a satellite lightning imager, such as the future GOES-R Geostationary Lightning Mapper (GLM), would likely improve operational and scientific applications (e.g., severe weather warnings, lightning nitrogen oxides studies, and global electric circuit analyses). A Bayesian inversion method, called the Ground Flash Fraction Retrieval Algorithm (GoFFRA), was recently developed for estimating the ground flash fraction. The method uses a constrained mixed exponential distribution model to describe a particular lightning optical measurement called the Maximum Group Area (MGA). To obtain the optimum model parameters (one of which is the desired ground flash fraction), a scalar function must be minimized. This minimization is difficult because of two problems: (1) Label Switching (LS), and (2) Parameter Identity Theft (PIT). The LS problem is well known in the literature on mixed exponential distributions, and the PIT problem was discovered in this study. Each problem occurs when one allows the numerical minimizer to freely roam through the parameter search space; this allows certain solution parameters to interchange roles which leads to fundamental ambiguities, and solution error. A major accomplishment of this study is that we have employed a state-of-the-art genetic-based global optimization algorithm called Differential Evolution (DE) that constrains the parameter search in such a way as to remove both the LS and PIT problems. To test the performance of the GoFFRA when DE is employed, we applied it to analyze simulated MGA datasets that we generated from known mixed exponential distributions. Moreover, we evaluated the GoFFRA/DE method by applying it to analyze actual MGAs derived from low-Earth orbiting lightning imaging sensor data; the actual MGA data were classified as either ground or cloud flash MGAs using National Lightning Detection Network[TM] (NLDN) data. Solution error plots are provided for both the simulations and actual data analyses.

Severe storm electricity

NASA Technical Reports Server (NTRS)

Rust, W. D.; Macgorman, D. R.; Taylor, W.; Arnold, R. T.

1984-01-01

Severe storms and lightning were measured with a NASA U2 and ground based facilities, both fixed base and mobile. Aspects of this program are reported. The following results are presented: (1) ground truth measurements of lightning for comparison with those obtained by the U2. These measurements include flash type identification, electric field changes, optical waveforms, and ground strike location; (2) simultaneous extremely low frequency (ELF) waveforms for cloud to ground (CG) flashes; (3) the CG strike location system (LLP) using a combination of mobile laboratory and television video data are assessed; (4) continued development of analog-to-digital conversion techniques for processing lightning data from the U2, mobile laboratory, and NSSL sensors; (5) completion of an all azimuth TV system for CG ground truth; (6) a preliminary analysis of both IC and CG lightning in a mesocyclone; and (7) the finding of a bimodal peak in altitude lightning activity in some storms in the Great Plains and on the east coast. In the forms on the Great Plains, there was a distinct class of flash what forms the upper mode of the distribution. These flashes are smaller horizontal extent, but occur more frequently than flashes in the lower mode of the distribution.

James L. Tuck Los Alamos ball lightning pioneer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, D.A.

1999-07-01

James Tuck was well known for starting the Project Sherwood group at Los Alamos Scientific Laboratory in 1952. This group was formed to study and develop concepts for controlled fusion energy. In his later years after retiring from Controlled Fusion Division, he continued research at Los Alamos on the topic of ball lightning. He traveled widely giving lectures on both observations of others and his own experimental efforts. He collected anecdotal observations obtained from those in his lecture audiences during his travels and from responses from newspaper articles where he asked for specific information from ball lightning observers. He finallymore » cut off this collection of data when the number of responses became overwhelming. The author's primary publication on ball lightning was a short laboratory report. He planned on publishing a book on the subject but this was never completed before his death. Tuck focused his experimental effort on attempting to duplicate the production of plasma balls claimed to be observed in US Navy submarines when a switch was opened under overload conditions with battery power. During lunch breaks he made use of a Los Alamos N-division battery bank facility to mock up a submarine power pack and switch gear. This non-funded effort was abruptly terminated when an explosion occurred in the facility. An overview of Tuck's research and views will be given. The flavor Jim's personality as well as a ball produced with his experimental apparatus will be shown using video chips.« less

Lightning Strike Induced Damage Mechanisms of Carbon Fiber Composites

NASA Astrophysics Data System (ADS)

Kawakami, Hirohide

Composite materials have a wide application in aerospace, automotive, and other transportation industries, because of the superior structural and weight performances. Since carbon fiber reinforced polymer composites possess a much lower electrical conductivity as compared to traditional metallic materials utilized for aircraft structures, serious concern about damage resistance/tolerance against lightning has been rising. Main task of this study is to clarify the lightning damage mechanism of carbon fiber reinforced epoxy polymer composites to help further development of lightning strike protection. The research on lightning damage to carbon fiber reinforced polymer composites is quite challenging, and there has been little study available until now. In order to tackle this issue, building block approach was employed. The research was started with the development of supporting technologies such as a current impulse generator to simulate a lightning strike in a laboratory. Then, fundamental electrical properties and fracture behavior of CFRPs exposed to high and low level current impulse were investigated using simple coupon specimens, followed by extensive parametric investigations in terms of different prepreg materials frequently used in aerospace industry, various stacking sequences, different lightning intensity, and lightning current waveforms. It revealed that the thermal resistance capability of polymer matrix was one of the most influential parameters on lightning damage resistance of CFRPs. Based on the experimental findings, the semi-empirical analysis model for predicting the extent of lightning damage was established. The model was fitted through experimental data to determine empirical parameters and, then, showed a good capability to provide reliable predictions for other test conditions and materials. Finally, structural element level lightning tests were performed to explore more practical situations. Specifically, filled-hole CFRP plates and patch-repaired CFRP plates were selected as structural elements likely to be susceptible to lightning event. This study forms a solid foundation for the understanding of lightning damage mechanism of CFRPs, and become an important first step toward building a practical damage prediction tool of lighting event.

Interannual variability in tropical tropospheric ozone and OH: The role of lightning

NASA Astrophysics Data System (ADS)

Murray, Lee T.; Logan, Jennifer A.; Jacob, Daniel J.

2013-10-01

Nitrogen oxide radicals (NOx) produced by lightning are natural precursors for the production of the dominant tropospheric oxidants, OH and ozone. Observations of the interannual variability (IAV) of tropical ozone and of global mean OH (from the methyl chloroform proxy) offer a window for understanding the sensitivity of ozone and OH to environmental factors. We present the results of simulations for 1998-2006 using the GEOS-Chem chemical transport model (CTM) with IAV in tropical lightning constrained by satellite observations from the Lightning Imaging Sensor. We find that this imposed IAV in lightning NOx improves the ability of the model to reproduce observed IAV in tropical ozone and OH. Lightning is far more important than biomass burning in driving the IAV of tropical ozone, even though the IAV of NOx emissions from fires is greater than that from lightning. Our results indicate that the IAV in tropospheric OH is highly sensitive to lightning relative to other emissions and suggest that lightning contributes an important fraction of the observed IAV in OH inferred from the methyl chloroform proxy. Lightning affects OH through the HO2+ NO reaction, an effect compounded by positive feedback from the resulting increase in ozone production and in CO loss. We can account in the model for the observed increase in OH in 1998-2004 and for its IAV, but the model fails to explain the OH decrease in 2004-2006. We find that stratospheric ozone plays little role in driving IAV in OH during 1998-2006, in contrast to previous studies that examined earlier periods.

Evaluation of Transient Pin-Stress Requirements for Spacecraft Launching in Lightning Environments. Pain Free Analysis to Alleviate Those Pin Stress Headaches

NASA Technical Reports Server (NTRS)

Edwards, Paul; Terseck, Alex; Trout, Dawn

2016-01-01

Spacecraft are generally protected from direct lightning attachment by encapsulation within the payload fairing of a launch vehicle and the ground structures that exist at the launch site. Regardless of where lightning strikes, potentially damaging indirect effects prevail from the coupling of electromagnetic fields into a loop created by outer shield of the payload umbilical. The energy coupled into individual spacecraft circuits is dependent on the umbilical current drive, the cable transfer impedance and the source/ load circuitry, and the reference potential used. Lightning induced transient susceptibility of the spacecraft avionics needs to be fully understood in order to define realistic re-test criteria in the event of a lightning occurrence during the launch campaign. Use of standards such as RTCA/DO-160 & SAE 5412 has some applicability but do not represent the indirect environment adequately. This paper evaluates the launch pad environments, the measurement data available, and computer simulations to provide pain-free analysis to alleviate the transient pin-stress headaches for spacecraft launching in Lightning environments.

Modeling Techniques Used to Analyze Safety of Payloads for Generic Missile Type Weapons Systems During an Indirect Lightning Strike

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perkins, M P; Ong, M M; Crull, E W

2009-07-21

During lightning strikes buildings and other structures can act as imperfect Faraday Cages, enabling electromagnetic fields to be developed inside the facilities. Some equipment stored inside these facilities may unfortunately act as antenna systems. It is important to have techniques developed to analyze how much voltage, current, or energy dissipation may be developed over valuable components. In this discussion we will demonstrate the modeling techniques used to accurately analyze a generic missile type weapons system as it goes through different stages of assembly. As work is performed on weapons systems detonator cables can become exposed. These cables will form differentmore » monopole and loop type antenna systems that must be analyzed to determine the voltages developed over the detonator regions. Due to the low frequencies of lightning pulses, a lumped element circuit model can be developed to help analyze the different antenna configurations. We will show an example of how numerical modeling can be used to develop the lumped element circuit models used to calculate voltage, current, or energy dissipated over the detonator region of a generic missile type weapons system.« less

Relationship Between the Electromagnetic Wave Energy Coupled by Overhead Lines and the Radiation Source Current Explored in the Laboratory

NASA Astrophysics Data System (ADS)

Li, Xiangchao; Wan, Zhicheng

2018-04-01

In order to solve the damage and interference problems to the electronic devices, which are induced by overvoltage excited by the coupling process between lightning electromagnetic wave and overhead lines, the lightning channel is set to be equivalent to a radiant wire antenna. Based on the integration model of lightning return stroke channel, transmission line, and ground, we take advantage of the derived formula gotten from the transmission line model. By combing the theoretical and experimental methods, we conduct a comparative analysis on the coupling process between natural/simulated lightning and overhead line. Besides, we also calculate the amplitude and energy of overvoltage, which is caused by the coupling process between lightning electromagnetic wave and overhead lines. Upon these experimental results, we can draw several conclusions as follows: when the amplitude of the lightning current in the channel is between 5 kA and 41 kA, it takes on an excellent linear relation between the amplitude of overvoltage and the magnitude of the lightning current, the relation between coupling energy and magnitude of the lightning current takes on an exponential trend. When lightning wave transmits on the transmission lines, the high-order mode will be excited. Through analysis on the high-order mode's characteristics, we find that the theoretical analysis is consistent with the experimental results, which has a certain reference value to the protection on overhead lines.

Mathematical Inversion of Lightning Data: Techniques and Applications

NASA Technical Reports Server (NTRS)

Koshak, William

2003-01-01

A survey of some interesting mathematical inversion studies dealing with radio, optical, and electrostatic measurements of lightning are presented. A discussion of why NASA is interested in lightning, what specific physical properties of lightning are retrieved, and what mathematical techniques are used to perform the retrievals are discussed. In particular, a relatively new multi-station VHF time-of-arrival (TOA) antenna network is now on-line in Northern Alabama and will be discussed. The network, called the Lightning Mapping Array (LMA), employs GPS timing and detects VHF radiation from discrete segments (effectively point emitters) that comprise the channel of lightning strokes within cloud and ground flashes. The LMA supports on-going ground-validation activities of the low Earth orbiting Lightning Imaging Sensor (LIS) satellite developed at NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama. The LMA also provides detailed studies of the distribution and evolution of thunderstorms and lightning in the Tennessee Valley, and offers interesting comparisons with other meteorological/geophysical datasets. In order to take full advantage of these benefits, it is essential that the LMA channel mapping accuracy (in both space and time) be fully characterized and optimized. A new channel mapping retrieval algorithm is introduced for this purpose. To characterize the spatial distribution of retrieval errors, the algorithm has been applied to analyze literally tens of millions of computer-simulated lightning VHF point sources that have been placed at various ranges, azimuths, and altitudes relative to the LMA network. Statistical results are conveniently summarized in high-resolution, color-coded, error maps.

Simulating the effect of ignition source type on forest fire statistics

NASA Astrophysics Data System (ADS)

Krenn, Roland; Hergarten, Stefan

2010-05-01

Forest fires belong to the most frightening natural hazards, and have long-term ecological and economic effects on the regions involved. It was found that their frequency-area distributions show power-law behaviour under a wide variety of conditions, interpreting them as a self-organised critical phenomenon. Using computer simulations, self-organised critical behaviour manifests in simple cellular automaton models. With respect to ignition source, forest fires can be categorised as lightning-induced or as a result of human activity. Lightning fires are considered to be natural, whereas ``man made'' fires are frequently caused by some sort of technological disaster, such as sparks from wheels of trains, the rupture of overhead electrical lines, the misuse of electrical or mechanical devices and so on. Taking into account that such events rarely occur deep in the woods, man made fires should start preferably on the edge of a forest or where the forest is not very dense. We present a modification in the self-organised critical Drossel-Schwabl forest fire model that takes these two different triggering mechanisms into account and increases the scaling exponent of the frequency-area distribution by ca. 1/3. Combined simulations further predict a dependence of the overall event-size distribution on the ratio of lightning-induced and man made fires as well as a splitting of their partial distributions. Lightning is identified as the dominant mechanism in the regime of the largest fires. The results are confirmed by the analysis of the Canadian Large Fire Database and suggest that lightning-induced and man made forest fires cannot be treated separately in wildfire modelling, hazard assessment and forest management.

Imaging Sensor Flight and Test Equipment Software

NASA Technical Reports Server (NTRS)

Freestone, Kathleen; Simeone, Louis; Robertson, Byran; Frankford, Maytha; Trice, David; Wallace, Kevin; Wilkerson, DeLisa

2007-01-01

The Lightning Imaging Sensor (LIS) is one of the components onboard the Tropical Rainfall Measuring Mission (TRMM) satellite, and was designed to detect and locate lightning over the tropics. The LIS flight code was developed to run on a single onboard digital signal processor, and has operated the LIS instrument since 1997 when the TRMM satellite was launched. The software provides controller functions to the LIS Real-Time Event Processor (RTEP) and onboard heaters, collects the lightning event data from the RTEP, compresses and formats the data for downlink to the satellite, collects housekeeping data and formats the data for downlink to the satellite, provides command processing and interface to the spacecraft communications and data bus, and provides watchdog functions for error detection. The Special Test Equipment (STE) software was designed to operate specific test equipment used to support the LIS hardware through development, calibration, qualification, and integration with the TRMM spacecraft. The STE software provides the capability to control instrument activation, commanding (including both data formatting and user interfacing), data collection, decompression, and display and image simulation. The LIS STE code was developed for the DOS operating system in the C programming language. Because of the many unique data formats implemented by the flight instrument, the STE software was required to comprehend the same formats, and translate them for the test operator. The hardware interfaces to the LIS instrument using both commercial and custom computer boards, requiring that the STE code integrate this variety into a working system. In addition, the requirement to provide RTEP test capability dictated the need to provide simulations of background image data with short-duration lightning transients superimposed. This led to the development of unique code used to control the location, intensity, and variation above background for simulated lightning strikes at user-selected locations.

Study on the luminous characteristics of a natural ball lightning

NASA Astrophysics Data System (ADS)

Wang, Hao; Yuan, Ping; Cen, Jianyong; Liu, Guorong

2018-02-01

According to the optical images of the whole process of a natural ball lightning recorded by two slit-less spectrographs in the Qinghai plateau of China, the simulated observation experiment on the luminous intensity of the spherical light source was carried out. The luminous intensity and the optical power of the natural ball lightning in the wavelength range of 400-690 nm were estimated based on the experimental data and the Lambert-Beer Law. The results show that the maximum luminous intensity was about 1.24 × 105 cd in the initial stage of the natural ball lightning, and the maximum luminous intensity and the maximum optical power in most time of its life were about 5.9 × 104 cd and 4.2 × 103 W, respectively.

Digital Simulation of Thunder from Three-Dimensional Lightning

NASA Astrophysics Data System (ADS)

Dunkin, James; Fleisch, Daniel

2010-04-01

The physics of lightning and its resultant thunder have been investigated by many people, but we still don't have a full understanding of the governing processes. In this study, we have constructed a three-dimensional model of lightning using MATLAB^ software, and used N-waves as postulated by Ribner and Roy to synthesize the resultant thunder signature. In addition, we have taken an FFT of the thunder signature, and compared the time-domain waveform and frequency spectrum to recordings of thunder taken over the summer of 2009. This analysis is done with the goal of further understanding the processes of thunder production.

The Role of Lightning in Controlling Interannual Variability of Tropical Tropospheric Ozone and OH and its Implications for Climate

NASA Technical Reports Server (NTRS)

Murray, Lee T.; Jacob, Daniel J.; Logan, Jennifer A.; Hudman, Rynda C.; Koshak, William J.

2012-01-01

Nitrogen oxides (NO(x) = NO + NO2) produced by lightning make a major contribution to the production of the dominant tropospheric oxidants (OH and ozone). These oxidants control the lifetime of many trace gases including long-lived greenhouse gases, and control the source-receptor relationship of inter-hemispheric pollutant transport. Lightning is affected by meteorological variability, and therefore represents a potentially important tropospheric chemistry-climate feedback. Understanding how interannual variability (IAV) in lightning affects IAV in ozone and OH in the recent past is important if we are to predict how oxidant levels may change in a future warmer climate. However, lightning parameterizations for chemical transport models (CTMs) show low skill in reproducing even climatological distributions of flash rates from the Lightning Imaging Sensor (LIS) and the Optical Transient Detector (OTD) satellite instruments. We present an optimized regional scaling algorithm for CTMs that enables sufficient sampling of spatiotemporally sparse satellite lightning data from LIS to constrain the spatial, seasonal, and interannual variability of tropical lightning. We construct a monthly time series of lightning flash rates for 1998-2010 and 35degS-35degN, and find a correlation of IAV in total tropical lightning with El Nino. We use the IAV-constraint to drive a 9-year hindcast (1998-2006) of the GEOS-Chem 3D chemical transport model, and find the increased IAV in LNO(x) drives increased IAV in ozone and OH, improving the model fs ability to simulate both. Although lightning contributes more than any other emission source to IAV in ozone, we find ozone more sensitive to meteorology, particularly convective transport. However, we find IAV in OH to be highly sensitive to lightning NO(x), and the constraint improves the ability of the model to capture the temporal behavior of OH anomalies inferred from observations of methyl chloroform and other gases. The sensitivity of OH is explained using photochemical reaction rates which show a "magnification" effect of the initial lightning NO perturbation on OH primary production, HO(x) recycling, and OH loss frequencies. This influence on OH may represent a negative feedback, if lightning increases in a warming world..

Impact of Lightning-NO Emissions on Summertime U.S. Photochemistry as Determined Using the CMAQ Model with NLDN-Constrained Flash Rates

NASA Technical Reports Server (NTRS)

Allen, Dale; Pickering, Kenneth; Pinder, Robert; Koshak, William; Pierce, Thomas

2011-01-01

Lightning-NO emissions are responsible for 15-30 ppbv enhancements in upper tropospheric ozone over the eastern United States during the summer time. Enhancements vary from year to year but were particularly large during the summer of 2006, a period during which meteorological conditions were particularly conducive to ozone formation. A lightning-NO parameterization has been developed that can be used with the CMAQ model. Lightning-NO emissions in this scheme are assumed to be proportional to convective precipitation rate and scaled so that monthly average flash rates in each grid box match National Lightning Detection Network (NLDN) observed flash rates after adjusting for climatological intracloud to cloud-to-ground (IC/CG) ratios. The contribution of lightning-NO emissions to eastern United States NOx and ozone distributions during the summer of 2006 will be evaluated by comparing results of 12- km CMAQ simulations with and without lightning-NO emissions to measurements from the IONS field campaign and to satellite retrievals from the Tropospheric Emission Spectrometer (TES) and the Ozone Monitoring Instrument (OMI) aboard the Aura satellite. Special attention will be paid to the impact of the assumed vertical distribution of emissions on upper tropospheric NOx and ozone amounts.

Lightning leader models of terrestrial gamma-ray flashes

NASA Astrophysics Data System (ADS)

Dwyer, J. R.; Liu, N.; Ihaddadene, K. M. A.

2017-12-01

Terrestrial gamma-ray flashes (TGFs) are bright sub-millisecond bursts of gamma rays that originate from thunderstorms. Because lightning leaders near the ground have been observed to emit x-rays, presumably due to runaway electron production in the high-field regions near the leader tips, models of TGFs have been developed by several groups that assume a similar production mechanism of runaway electrons from lightning leaders propagating through thunderclouds. However, it remains unclear exactly how and where these runaway electrons are produced, since lightning propagation at thunderstorm altitudes remains poorly understood. In addition, it is not obvious how to connect the observed behavior of the x-ray production from lightning near the ground with the properties of TGFs. For example, it is not clear how to relate the time structure of the x-ray emission near the ground to that of TGFs, since x-rays from stepped leaders near the ground are usually produced in a series of sub-microsecond bursts, but TGFs are usually observed as much longer pulses without clear substructures, at sub-microsecond timescales or otherwise. In this presentation, spacecraft observations of TGFs, ground-based observations of x-rays from lightning and laboratory sparks, and Monte Carlo and PIC simulations of runaway electron and gamma ray production and propagation will be used to constrain the lightning leader models of TGFs.

Follow-on cable coupling lightning test, volume 1

NASA Technical Reports Server (NTRS)

Danforth, Richard

1990-01-01

A redesigned solid rocket motor test article was subjected to simulated lightning strikes. This test was performed to evaluate the effects of lightning strike to the redesigned motor and Space Transportation System. The purpose of the test was to evaluate the performance of systems tunnel design changes when subjected to the lightning discharges. The goal of the design changes was to reduce lightning induced coupling to cables within the systems tunnel. The test article was subjected to several different amounts and kinds of discharges. Changes in coupling levels detected during the tests are recorded. The dominant mode of coupling appears to be caused by the diffusion of the magnetic fields through the system tunnel covers. The results from bond strap integrity testing showed that 16 of 18 bond straps survived. Design change evaluations showed that coupling reduction ranged from 0 to 36 decibels for each type of cable. The type of cable has less effect on coupling than does strike location and strike levels. Recommendations for design changes are made.

Lightning protection of the Fokker 100 CFRP rudder

NASA Technical Reports Server (NTRS)

Ruiter, A. J. M.

1991-01-01

The construction of the structural parts of the Fokker 100 CFRP rudder is described with respect to the requirements for electrical bonding and lightning protection. Furthermore, the philosophy for the selection of a consumable trailing edge is given. A description of possible alternative designs for trailing edges and their advantages and disadvantages with respect to damage after lightning impact will also be reviewed. An overview of the tests performed on test samples and the rudder construction are presented and discussed. The effectiveness of both the selected structural provisions and trailing edge are described (and proven) by reporting the results of the simulated lightning tests performed. Proof is given that the trailing edge construction and its bonding through the structural parts of the rudder to the main aircraft structure is a solution which results in minor damage to the rudder after lightning impact. Furthermore, it is shown that the selected trailing edge construction is less favored by the structural designers due to the weight penalty.

North Alabama Lightning Mapping Array (LMA): VHF Source Retrieval Algorithm and Error Analyses

NASA Technical Reports Server (NTRS)

Koshak, W. J.; Solakiewicz, R. J.; Blakeslee, R. J.; Goodman, S. J.; Christian, H. J.; Hall, J.; Bailey, J.; Krider, E. P.; Bateman, M. G.; Boccippio, D.

2003-01-01

Two approaches are used to characterize how accurately the North Alabama Lightning Mapping Array (LMA) is able to locate lightning VHF sources in space and in time. The first method uses a Monte Carlo computer simulation to estimate source retrieval errors. The simulation applies a VHF source retrieval algorithm that was recently developed at the NASA Marshall Space Flight Center (MSFC) and that is similar, but not identical to, the standard New Mexico Tech retrieval algorithm. The second method uses a purely theoretical technique (i.e., chi-squared Curvature Matrix Theory) to estimate retrieval errors. Both methods assume that the LMA system has an overall rms timing error of 50 ns, but all other possible errors (e.g., multiple sources per retrieval attempt) are neglected. The detailed spatial distributions of retrieval errors are provided. Given that the two methods are completely independent of one another, it is shown that they provide remarkably similar results. However, for many source locations, the Curvature Matrix Theory produces larger altitude error estimates than the (more realistic) Monte Carlo simulation.

Angular Distribution of light emission in ELVES events

NASA Astrophysics Data System (ADS)

Mussa, Roberto

2017-04-01

The Pierre Auger Observatory, located in Malargüe (Argentina), is the largest facility (3000 kmq ) for the study of Ultra High Energy Cosmic Rays (E>0.3 EeV). The four sites of the Fluorescence Detector (FD) are continuously observing the night sky with moon fraction below 50% (13% duty cycle) with 100 ns time resolution and a space resolution below one degree. Since 2013, the Observatory has implemented a dedicated trigger for the study of ELVES events, produced by lightning activity in Northern Argentina during summer months. A network of ancillary devices (lidars, cloud cameras, weather stations, lightning sensors, E-field mills) complements the FD data to correct for the variation of atmospheric optical properties. This paper will report about the angular distribution of the light emission around the vertical above the lightning source and compare with existing models.

Rocket-triggered lightning strikes and forest fire ignition

NASA Technical Reports Server (NTRS)

Fenner, James

1990-01-01

The following are presented: (1) background information on the rocket-triggered lightning project an Kennedy Space Center (KSC); (2) a summary of the forecasting problem; (3) the facilities and equipment available for undertaking field experiments at KSC; (4) previous research activity performed; (5) a description of the atmospheric science field laboratory near Mosquito Lagoon on the KSC complex; (6) methods of data acquisition; and (7) present results. New sources of data for the 1990 field experiment include measuring the electric field in the lower few thousand feet of the atmosphere by suspending field measuring devices below a tethered balloon, and measuring the electric field intensity in clouds and in the atmosphere with aircraft. The latter program began in July of 1990. Also, future prospects for both triggered lightning and forest fire research at KSC are listed.

A preliminary test of the application of the Lightning Detection and Ranging System (LDAR) as a thunderstorm warning and location device for the FHA including a correlation with updrafts, turbulence, and radar precipitation echoes

NASA Technical Reports Server (NTRS)

Poehler, H. A.

1978-01-01

Results of a test of the use of a Lightning Detection and Ranging (LDAR) remote display in the Patrick AFB RAPCON facility are presented. Agreement between LDAR and radar precipitation echoes of the RAPCON radar was observed, as well as agreement between LDAR and pilot's visual observations of lightning flashes. A more precise comparison between LDAR and KSC based radars is achieved by the superposition of LDAR precipitation echoes. Airborne measurements of updrafts and turbulence by an armored T-28 aircraft flying through the thunderclouds are correlated with LDAR along the flight path. Calibration and measurements of the accuracy of the LDAR System are discussed, and the extended range of the system is illustrated.

New model simulations of the global atmospheric electric circuit driven by thunderstorms and electrified shower clouds: The roles of lightning and sprites

NASA Astrophysics Data System (ADS)

Rycroft, Michael J.; Odzimek, Anna; Arnold, Neil F.; Füllekrug, Martin; Kułak, Andrzej; Neubert, Torsten

2007-12-01

Several processes acting below, in and above thunderstorms and in electrified shower clouds drive upward currents which close through the global atmospheric electric circuit. These are all simulated in a novel way using the software package PSpice. A moderate negative cloud-to-ground lightning discharge from the base of a thunderstorm increases the ionospheric potential above the thundercloud by 0.0013%. Assuming the ionosphere to be an equipotential surface, this discharge increases the current flowing in the global circuit and the fair-weather electric field also by 0.0013%. A moderate positive cloud-to-ground lightning discharge from the bottom of a thunderstorm decreases the ionospheric potential by 0.014%. Such a discharge may trigger a sprite, causing the ionospheric potential to decrease by ˜1V. The time scales for the recovery of the ionospheric potential are shown to be ˜250s, which is of the same order as the CR time constant for the global circuit. Knowing the global average rate of lightning discharges, it is found that negative cloud-to-ground discharges increase the ionospheric potential by only ˜4%, and that positive cloud-to-ground discharges reduce it by ˜3%. Thus, overall, lightning contributes only ˜1%—an almost insignificant proportion—to maintaining the high potential of the ionosphere. It is concluded that the net upward current to the ionosphere due to lightning is only ˜20A. Further, it is concluded that conduction and convection currents associated with “batteries” within thunderclouds and electrified shower clouds contribute essentially equally (˜500A each) to maintaining the ionospheric potential.

Assessing the Parameterization of Nitric Oxide Emissions By Lightning in a Chemical Transport Model with Nitric Acid Columns from the IASI Satellite Instrument

NASA Astrophysics Data System (ADS)

Cooper, M.; Martin, R.; Wespes, C.; Coheur, P. F.; Clerbaux, C.; Murray, L. T.

2014-12-01

Nitrogen oxides (NOx ≡ NO + NO2) in the free troposphere largely control the production of ozone (O3), an important greenhouse gas and atmospheric oxidant. As HNO3 is the dominant sink of tropospheric NOx, improved understanding of its production and loss mechanisms can help to better constrain NOx emissions, and in turn improve understanding of ozone production and its effect on climate. However, this understanding is inhibited by the scarcity of direct measurements of free tropospheric HNO3, particularly in the tropics. We interpret tropical tropospheric nitric acid columns from the IASI satellite instrument with a global chemical transport model (GEOS-Chem). Overall GEOS-Chem generally agrees with IASI, however we find that the simulation underestimates IASI nitric acid over Southeast Asia by a factor of two. The bias is confirmed by comparing the GEOS-Chem simulation with additional satellite (HIRDLS, ACE-FTS) and aircraft (PEM-Tropics A and PEM-West B) observations of the middle and upper troposphere. We show that this bias can be explained by the parameterization of lightning NOx emissions, primarily from the misrepresentation of concentrated subgrid lightning NOx plumes. We tested a subgrid lightning plume parameterization and found that an additional 0.5 Tg N with an ozone production efficiency of 15 mol/mol would reduce the regional nitric acid bias from 92% to 6% without perturbing the rest of the tropics. Other sensitivity studies such as modified NOx yield per flash, increased altitude of lightning NOx emissions, or changes to convective mass flux or wet deposition of nitric acid required unrealistic changes to reduce the bias. This work demonstrates the importance of a comprehensive lightning parameterization to constraining NOx emissions.

A Preliminary ZEUS Lightning Location Error Analysis Using a Modified Retrieval Theory

NASA Technical Reports Server (NTRS)

Elander, Valjean; Koshak, William; Phanord, Dieudonne

2004-01-01

The ZEUS long-range VLF arrival time difference lightning detection network now covers both Europe and Africa, and there are plans for further expansion into the western hemisphere. In order to fully optimize and assess ZEUS lightning location retrieval errors and to determine the best placement of future receivers expected to be added to the network, a software package is being developed jointly between the NASA Marshall Space Flight Center (MSFC) and the University of Nevada Las Vegas (UNLV). The software package, called the ZEUS Error Analysis for Lightning (ZEAL), will be used to obtain global scale lightning location retrieval error maps using both a Monte Carlo approach and chi-squared curvature matrix theory. At the core of ZEAL will be an implementation of an Iterative Oblate (IO) lightning location retrieval method recently developed at MSFC. The IO method will be appropriately modified to account for variable wave propagation speed, and the new retrieval results will be compared with the current ZEUS retrieval algorithm to assess potential improvements. In this preliminary ZEAL work effort, we defined 5000 source locations evenly distributed across the Earth. We then used the existing (as well as potential future ZEUS sites) to simulate arrival time data between source and ZEUS site. A total of 100 sources were considered at each of the 5000 locations, and timing errors were selected from a normal distribution having a mean of 0 seconds and a standard deviation of 20 microseconds. This simulated "noisy" dataset was analyzed using the IO algorithm to estimate source locations. The exact locations were compared with the retrieved locations, and the results are summarized via several color-coded "error maps."

Predicting Impacts of Lightning Strikes on Aviation under a Changing Climate Using Regression Kriging

NASA Astrophysics Data System (ADS)

Rakas, J.; Ding, C.; Murthi, A.; Lukovic, J.; Bajat, B.

2016-12-01

Lightning is a serious hazard that can cause significant impacts on human infrastructure. In the aviation industry, lightning strikes cause damage and outages to air traffic control equipment and facilities at airports that result in major disruptions in commercial air travel, compounding delays during storm events that lead to losses in the millions of dollars. To date poor attention has been given to how lightning might change with the increase of greenhouse gases and temperature. Under some climate change scenarios, the increase in the occurrence and severity of storms in the future with potential for increases in lightning activity has been studied. Recent findings suggest that lighting rates will increase 12 percent per every degree Celsius rise in global temperatures. That will results to a 50 percent increase by the end of the century. Accurate prediction of the intensity and frequency of lightning strikes is therefore required by the air traffic management and control sector in order to develop more robust adaptation and mitigation strategies under the threat of global climate change and increasing lightning rates. In this work, we use the regression kriging method to predict lightning strikes over several regions over the contiguous United Sates using two meteorological variables- namely convective available potential energy (CAPE) and total precipitation rate. These two variables are used as a measure of storm convection, since strong convections are related to more lightning. Specifically, CAPE multiplied by precipitation is used as a proxy for lightning strikes owing to a strong linear relationship between the two. These two meteorological variables are obtained from a subset of models used in phase 5 of the coupled model inter-comparison experiment pertaining to the "high emissions" climate change scenario corresponding to the representative concentration pathway (RCP) 8.5. Precipitation observations from the National Weather Cooperative Network (COOP) were incorporated as an additional dataset. This scenario indicates a doubling of CAPE and precipitation resulting in significant increases in CAPE×precipitation by the end of the century. Overall, this research highlights the use of global climate models and observations to assess climate change impacts on aviation.

Analysis and Modeling of Trace Gases and Aerosols in Severe Convection: The 22 June 2012 DC3 Case

NASA Astrophysics Data System (ADS)

Barth, M. C.; Apel, E. C.; Bela, M.; Fried, A.; Fuchs, B.; Pickering, K. E.; Pollack, I. B.; Rutledge, S. A.

2016-12-01

The Deep Convective Clouds and Chemistry (DC3) field campaign aimed to quantify and characterize the dynamics, physics, lightning, and transport of trace gases and aerosols in convection, as well as the chemical aging of convective outflow plumes in the upper troposphere. These goals were met by deploying radars, lightning mapping arrays, weather balloons, and aircraft to sample storms in northeast Colorado, west Texas to central Oklahoma, and northern Alabama. Here, we use one case, 22 June 2012 severe convection in northeast Colorado and southwest Nebraska, as an example for quantifying and predicting convective transport of trace gases and aerosols, lightning flash rate, lightning production of nitrogen oxides, and subsequent ozone production downwind of the storms. This case was unique in that one severe storm ingested a wildfire smoke plume at 7 km altitude while other storms in the area did not. Several analyses of this case have been done using the aircraft composition measurements, dual-Doppler and polarimetric radar products, and lightning mapping array data. It was determined that the storm unaffected by the High Park fire smoke plume had a 4.8±0.9%/km entrainment rate and estimated scavenging efficiencies of CH2O, H2O2, CH3OOH, SO2, and HNO3 of 41±4%, 79±19, 44±47%, 92±4%, 95±12%, respectively. Total (intracloud and cloud-to-ground) lightning flash rates were 98-106 flashes per minute when the aircraft were sampling the outflow of the storms, resulting in an estimate of lightning-NOx production of 142±25 moles NO per flash. Box modeling simulations estimate the production of O3 in the convective outflow of these storms to be 11-14 ppbv over 2 days. These results are used to evaluate the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to learn how well a state-of-the-art model represents the storm processing of trace gases. The WRF-Chem simulations are analyzed further to examine the effect of aerosols in the smoke plume on the storm characteristics, including precipitation, convective transport, lightning flash rate, and lightning-NOx production.

An Overview of the Lightning - Atmospheric Chemistry Aspects of the Deep Convective Clouds and Chemistry (DC3) Experiment

NASA Technical Reports Server (NTRS)

Pickering, K. E.; Barth, M. C.; Koshak, W.; Bucsela, E. J.; Allen, D. J.; Weinheimer, A.; Ryerson, T.; Huntrieser, H.; Bruning, E.; MacGorman, D.;

An Integrated 0-1 Hour First-Flash Lightning Nowcasting, Lightning Amount and Lightning Jump Warning Capability

NASA Technical Reports Server (NTRS)

Mecikalski, John; Jewett, Chris; Carey, Larry; Zavodsky, Brad; Stano, Geoffrey

2015-01-01

Lightning one of the most dangerous weather-related phenomena, especially as many jobs and activities occur outdoors, presenting risk from a lightning strike. Cloud-to-ground (CG) lightning represents a considerable safety threat to people at airfields, marinas, and outdoor facilities-from airfield personnel, to people attending outdoor stadium events, on beaches and golf courses, to mariners, as well as emergency personnel. Holle et al. (2005) show that 90% of lightning deaths occurred outdoors, while 10% occurred indoors despite the perception of safety when inside buildings. Curran et al. (2000) found that nearly half of fatalities due to weather were related to convective weather in the 1992-1994 timeframe, with lightning causing a large component of the fatalities, in addition to tornadoes and flash flooding. Related to the aviation industry, CG lightning represents a considerable hazard to baggage-handlers, aircraft refuelers, food caterers, and emergency personnel, who all become exposed to the risk of being struck within short time periods while convective storm clouds develop. Airport safety protocols require that ramp operations be modified or discontinued when lightning is in the vicinity (typically 16 km), which becomes very costly and disruptive to flight operations. Therefore, much focus has been paid to nowcasting the first-time initiation and extent of lightning, both of CG and of any lightning (e.g, in-cloud, cloud-to-cloud). For this project three lightning nowcasting methodologies will be combined: (1) a GOESbased 0-1 hour lightning initiation (LI) product (Harris et al. 2010; Iskenderian et al. 2012), (2) a High Resolution Rapid Refresh (HRRR) lightning probability and forecasted lightning flash density product, such that a quantitative amount of lightning (QL) can be assigned to a location of expected LI, and (3) an algorithm that relates Pseudo-GLM data (Stano et al. 2012, 2014) to the so-called "lightning jump" (LJ) methodology (Shultz et al. 2011) to monitor lightning trends and to anticipate/forecast severe weather (hail > or =2.5 cm, winds > or =25 m/s, tornadoes). The result will be a time-continuous algorithm that uses GOES satellite, radar fields, and HRRR model fields to nowcast first-flash LI and QL, and subsequently monitors lightning trends on a perstorm basis within the LJ algorithm for possible severe weather occurrence out to > or =3 hours. The LI-QL-LJ product will also help prepare the operational forecast community for Geostationary Lightning Mapper (GLM) data expected in late 2015, as these data are monitored for ongoing convective storms. The LI-QL-LJ product will first predict where new lightning is highly probable using GOES imagery of developing cumulus clouds, followed by n analysis of NWS (dual-polarization) radar indicators (reflectivity at the -10 C altitude) of lightning occurrence, to increase confidence that LI is immanent. Once lightning is observed, time-continuous lightning mapping array and Pseudo-GLM observations will be analyzed to assess trends and the severe weather threat as identified by trends in lightning (i.e. LJs). Additionally, 5- and 15-min GOES imagery will then be evaluated on a per-storm basis for overshooting and other cloud-top features known to be associated with severe storms. For the processing framework, the GOES-R 0-1 hour convective initiation algorithm's output will be developed within the Warning Decision Support System - Integrated Information (WDSS-II) tracking tool, and merged with radar and lightning (LMA/Psuedo-GLM) datasets for active storms. The initial focus of system development will be over North Alabama for select lightning-active days in summer 2014, yet will be formed in an expandable manner. The lightning alert tool will also be developed in concert with National Weather Service (NWS) forecasters to meet their needs for real-time, accurate first-flash LI and timing, as well as anticipated lightning trends, amounts, continuation and cessation, so to provide key situational awareness and decision support information. The NASA Short-term Prediction Research and Transition (SPoRT) Center will provide important logistical and collaborative support and training, involving interactions with the NWS and broader user community.

Production of NOx by Lightning and its Effects on Atmospheric Chemistry

NASA Technical Reports Server (NTRS)

Pickering, Kenneth E.

2009-01-01

Production of NO(x) by lightning remains the NO(x) source with the greatest uncertainty. Current estimates of the global source strength range over a factor of four (from 2 to 8 TgN/year). Ongoing efforts to reduce this uncertainty through field programs, cloud-resolved modeling, global modeling, and satellite data analysis will be described in this seminar. Representation of the lightning source in global or regional chemical transport models requires three types of information: the distribution of lightning flashes as a function of time and space, the production of NO(x) per flash, and the effective vertical distribution of the lightning-injected NO(x). Methods of specifying these items in a model will be discussed. For example, the current method of specifying flash rates in NASA's Global Modeling Initiative (GMI) chemical transport model will be discussed, as well as work underway in developing algorithms for use in the regional models CMAQ and WRF-Chem. A number of methods have been employed to estimate either production per lightning flash or the production per unit flash length. Such estimates derived from cloud-resolved chemistry simulations and from satellite NO2 retrievals will be presented as well as the methodologies employed. Cloud-resolved model output has also been used in developing vertical profiles of lightning NO(x) for use in global models. Effects of lightning NO(x) on O3 and HO(x) distributions will be illustrated regionally and globally.

Monte Carlo Radiative Transfer Modeling of Lightning Observed in Galileo Images of Jupiter

NASA Technical Reports Server (NTRS)

Dyudine, U. A.; Ingersoll, Andrew P.

2002-01-01

We study lightning on Jupiter and the clouds illuminated by the lightning using images taken by the Galileo orbiter. The Galileo images have a resolution of 25 km/pixel and axe able to resolve the shape of the single lightning spots in the images, which have full widths at half the maximum intensity in the range of 90-160 km. We compare the measured lightning flash images with simulated images produced by our ED Monte Carlo light-scattering model. The model calculates Monte Carlo scattering of photons in a ED opacity distribution. During each scattering event, light is partially absorbed. The new direction of the photon after scattering is chosen according to a Henyey-Greenstein phase function. An image from each direction is produced by accumulating photons emerging from the cloud in a small range (bins) of emission angles. Lightning bolts are modeled either as points or vertical lines. Our results suggest that some of the observed scattering patterns axe produced in a 3-D cloud rather than in a plane-parallel cloud layer. Lightning is estimated to occur at least as deep as the bottom of the expected water cloud. For the six cases studied, we find that the clouds above the lightning are optically thick (tau > 5). Jovian flashes are more regular and circular than the largest terrestrial flashes observed from space. On Jupiter there is nothing equivalent to the 30-40-km horizontal flashes which axe seen on Earth.

Facilities for meteorological research at NASA Goddard/Wallops Flight Facility

NASA Technical Reports Server (NTRS)

Gerlach, J. C.; Carr, R. E.

1984-01-01

The technical characteristics of the Atmospheric Sciences Research Facility, the improvements being made to the instrumentation there which will enhance its usefulness in atmospheric research, and several of the on-going research programs are described. Among the area of atmospheric research discussed are clouds and precipitation, lightning, ozone, wind, and storms. Meteorological instruments including Doppler radar, spectrophotometers, and ozone sensors are mentioned. Atmospheric research relevant to aircraft design and COMSTAR communication satellites is briefly discussed.

Digital system upset. The effects of simulated lightning-induced transients on a general-purpose microprocessor

NASA Technical Reports Server (NTRS)

Belcastro, C. M.

1983-01-01

Flight critical computer based control systems designed for advanced aircraft must exhibit ultrareliable performance in lightning charged environments. Digital system upset can occur as a result of lightning induced electrical transients, and a methodology was developed to test specific digital systems for upset susceptibility. Initial upset data indicates that there are several distinct upset modes and that the occurrence of upset is related to the relative synchronization of the transient input with the processing sate of the digital system. A large upset test data base will aid in the formulation and verification of analytical upset reliability modeling techniques which are being developed.

Study on the Transient Process of 500kV Substations Secondary Equipment

NASA Astrophysics Data System (ADS)

Li, Hongbo; Li, Pei; Zhang, Yanyan; Niu, Lin; Gao, Nannan; Si, Tailong; Guo, Jiadong; Xu, Min-min; Li, Guofeng; Guo, Liangfeng

2017-05-01

By analyzing on the reason of the lightning accident occur in the substation, the way of lightning incoming surge invading the secondary system is summarized. The interference source acts on the secondary system through various coupling paths. It mainly consists of four ways: the conductance coupling mode, the Capacitive Coupling Mode, the inductive coupling mode, The Radiation Interference Model. Then simulated the way with the program-ATP. At last, from the three aspects of low-voltage power supply system, the impact potential distribution of grounding grid, the secondary system and the computer system. The lightning protection measures is put forward.

Kennedy Space Center (KSC) Pad B Catenary Capability Analysis and Technical Exchange Meeting (TEM) Support

NASA Technical Reports Server (NTRS)

Wilson, Timmy R.; Kichak, Robert; Rakov, Vladimir; Kithil, Richard, Jr.; Sargent, Noel B.

2009-01-01

The existing lightning protection system at Pad 39B for the Space Shuttle is an outgrowth of a system that was put in place for the Apollo Program. Dr. Frank Fisher of Lightning Technologies was a key participant in the design and implementation of that system. He conveyed to the NESC team that the catenary wire provision was put in place quickly (as assurance against possible vehicle damage causing critical launch delays) rather than being implemented as a comprehensive system designed to provide a high degree of guaranteed protection. Also, the technology of lightning protection has evolved over time with considerable work being conducted by groups such as the electric utilities companies, aircraft manufacturers, universities, and others. Several accepted present-day methods for analysis of lightning protection were used by Drs. Medelius and Mata to study the expected lightning environment for the Pad 39B facility and to analyze the degree of protection against direct lightning attachment to the Space Shuttle. The specific physical configuration directly affects the vulnerability, so cases that were considered included the RSS next to and rolled back from the Space Shuttle, and the GOx Vent Arm both extended and withdrawn from the ET. Elements of the lightning protection system at Pad 39B are shown in Figure 6.0-1 and consist of an 80 foot insulating mast on top of the Fixed Support Structure (FSS), a catenary wire system that runs from the mast in a North/South direction to grounds 1000 feet away on each side of the mast, the RSS which can either be next to or away from the Space Shuttle, and a GOx vent that can either be extended or retracted from the top of the ET.

Application of Lidar Data to the Performance Evaluations of ...

EPA Pesticide Factsheets

The Tropospheric Ozone (O3) Lidar Network (TOLNet) provides time/height O3 measurements from near the surface to the top of the troposphere to describe in high-fidelity spatial-temporal distributions, which is uniquely useful to evaluate the temporal evolution of O3 profiles in air quality models. This presentation describes the application of the Lidar data to the performance evaluation of CMAQ simulated O3 vertical profiles during the summer, 2014. Two-way coupled WRF-CMAQ simulations with 12km and 4km domains centered over Boulder, Colorado were performed during this time period. The analysis on the time series of observed and modeled O3 mixing ratios at different vertical layers indicates that the model frequently underestimated the observed values, and the underestimation was amplified in the middle model layers (~1km above the ground). When the lightning strikes detected by the National Lightning Detection Network (NLDN) were analyzed along with the observed O3 time series, it was found that the daily maximum O3 mixing ratios correlated well with the lightning strikes in the vicinity of the Lidar station. The analysis on temporal vertical profiles of both observed and modeled O3 mixing ratios on episodic days suggests that the model resolutions (12km and 4km) do not make any significant difference for this analysis (at this specific location and simulation period), but high O3 levels in the middle layers were linked to lightning activity that occurred in t

Effects of Deep Convection on Atmospheric Chemistry

NASA Technical Reports Server (NTRS)

Pickering, Kenneth E.

2007-01-01

This presentation will trace the important research developments of the last 20+ years in defining the roles of deep convection in tropospheric chemistry. The role of deep convection in vertically redistributing trace gases was first verified through field experiments conducted in 1985. The consequences of deep convection have been noted in many other field programs conducted in subsequent years. Modeling efforts predicted that deep convection occurring over polluted continental regions would cause downstream enhancements in photochemical ozone production in the middle and upper troposphere due to the vertical redistribution of ozone precursors. Particularly large post-convective enhancements of ozone production were estimated for convection occurring over regions of pollution from biomass burning and urban areas. These estimates were verified by measurements taken downstream of biomass burning regions of South America. Models also indicate that convective transport of pristine marine boundary layer air causes decreases in ozone production rates in the upper troposphere and that convective downdrafts bring ozone into the boundary layer where it can be destroyed more rapidly. Additional consequences of deep convection are perturbation of photolysis rates, effective wet scavenging of soluble species, nucleation of new particles in convective outflow, and the potential fix stratosphere-troposphere exchange in thunderstorm anvils. The remainder of the talk will focus on production of NO by lightning, its subsequent transport within convective clouds . and its effects on downwind ozone production. Recent applications of cloud/chemistry model simulations combined with anvil NO and lightning flash observations in estimating NO Introduction per flash will be described. These cloud-resolving case-study simulations of convective transport and lightning NO production in different environments have yielded results which are directly applicable to the design of lightning parameterizations for global chemical transport models. The range of mean values (factor of 3) of NO production per flash (or per meter of lightning channel length) that have been deduced from the model will be shown and compared with values of production in the literature that have been deduced using other methods, Results show that on a per flash basis, IC flashes are nearly as productive of NO as CG flashes. When combined with the global flash rate of 44 flashes per second from NASA's Optical Transient Detector (OTD) measurements, these estimates and the results from other techniques yield global NO production rates of 2-9 TgN/year. Vertical profiles of lightning NOx mass at the end of the 3-D storm simulations have been summarized to yield suggested profiles for use in global models. Simulations of the photochemistry over the 24 hours following a storm have been performed to determine the additional ozone production which can be attributed to lightning NO.

LDAR, A Three-Dimensional Lightning Warning System: Its Development and Use by the Government, and Transition to Public Availability

NASA Technical Reports Server (NTRS)

Starr, Stan; Sharp, David; Merceret, Francis; Madura, John; Murphy, Martin

1998-01-01

NASA, at the John F. Kennedy Space Center (KSC), developed and operates a unique high precision lightning location system to provide lightning related weather warnings. These warnings are used to stop lightning-sensitive operations such as space vehicle launches and ground operations where equipment and personnel are at risk. The data is provided to the Range Weather Operations [45th Weather Squadron, U. S. Air Force (USAF)] where it is used with other meteorological data to issue weather advisories and warnings for Cape Canaveral Air Station (CCAS) and KSC operations. This system, called Lightning Detection and Ranging (LDAR), provides users with a graphical display in three dimensions of 66 MHz radio frequency events generated by lightning processes. The locations of these events provide a sound basis for the prediction of lightning hazards. NASA and Global Atmospherics, Inc. are developing a new system that will replace the unique LDAR components with commercially available and maintainable components having improved capabilities. These components will be phased in to ensure full continuity and access to this important warning technology. These LDAR systems are expected to eventually be available for installation and use by the public at specialized facilities, such as airports, and for general weather warnings via the National Weather Service (NWS) or television broadcast. The NWS in Melbourne has had access to real-time LDAR data since 1993 on an experimental basis. This use of LDAR has shown promise for the improvement of aviation forecasts and severe weather warnings. More so, it has opened the door to investigate the feasibility of issuing lightning-related public advisories. The success of its early use suggests that this technology may improve safety and potentially save lives, therefore constituting a significant benefit to the public. This paper describes the LDR system, the plans and progress of these upgrades, and the potential benefits of its use.

Lightning NOx Production and Transport in the 29 May 2012 DC3 case: A Modeling Study Using Radar Data Assimilation and a Branched Lightning Simulation.

NASA Astrophysics Data System (ADS)

Allen, B. J.; Mansell, E. R.; Betten, D.

2014-12-01

Open questions exist regarding chemical transport by convection and the sensitivity of Lightning Nitrogen Oxide (LNOx) production to flash type (IC vs. CG), channel height, and channel length. To help answer these and other questions, the Deep Convective Clouds and Chemistry (DC3) field project was conducted during the spring of 2012. On 29 May 2012, observations of an Oklahoma supercell were collected by two mobile SMART-R radars, the mobile NOXP radar, multiple NEXRAD radars, the Oklahoma Lightning Mapping Array (LMA), and the NSF/NCAR HIAPER and NASA DC-8 aircraft. In this study, data from the mobile and NEXRAD radars are assimilated into the NSSL COMMAS model using the Ensemble Kalman Filter, beginning shortly after initiation of convection and ending when the aircraft made their final measurements of the storm's outflow. The model analyses produce a realistic representation of the kinematic character of the storm throughout this time period. COMMAS includes the NSSL multimoment microphysics, explicit cloud electrification, and a branched lightning discharge scheme, which is used to produce LNOx within the model via a method dependent upon air pressure and lightning channel length. Model results will be presented and compared to radar, lightning, and aircraft observations. Of particular importance, the vertical distribution of lightning, channel length of lightning, and LNOx production and transport in the model will be analyzed and compared to LMA observations and anvil-level outflow observations from the aircraft. In addition, to examine entrainment and detrainment of air by the storm and to provide a check on LNOx production and transport, trajectory analyses will be presented and the transport of inert trace gases such as carbon monoxide in the model will be analyzed and compared to aircraft measurements.

Semi-idealized modeling of lightning initiation related to vertical air motion and cloud microphysics

NASA Astrophysics Data System (ADS)

Wang, Fei; Zhang, Yijun; Zheng, Dong; Xu, Liangtao; Zhang, Wenjuan; Meng, Qing

2017-10-01

A three-dimensional charge-discharge numerical model is used, in a semi-idealized mode, to simulate a thunder-storm cell. Characteristics of the graupel microphysics and vertical air motion associated with the lightning initiation are revealed, which could be useful in retrieving charge strength during lightning when no charge-discharge model is available. The results show that the vertical air motion at the lightning initiation sites ( W ini) has a cubic polynomial correlation with the maximum updraft of the storm cell ( W cell-max), with the adjusted regression coefficient R 2 of approximately 0.97. Meanwhile, the graupel mixing ratio at the lightning initiation sites ( q g-ini) has a linear correlation with the maximum graupel mixing ratio of the storm cell ( q g-cell-max) and the initiation height ( z ini), with the coefficients being 0.86 and 0.85, respectively. These linear correlations are more significant during the middle and late stages of lightning activity. A zero-charge zone, namely, the area with very low net charge density between the main positive and negative charge layers, appears above the area of q g-cell-max and below the upper edge of the graupel region, and is found to be an important area for lightning initiation. Inside the zero-charge zone, large electric intensity forms, and the ratio of q ice (ice crystal mixing ratio) to q g (graupel mixing ratio) illustrates an exponential relationship to q g-ini. These relationships provide valuable clues to more accurately locating the high-risk area of lightning initiation in thunderstorms when only dual-polarization radar data or outputs from numerical models without charging/discharging schemes are available. The results can also help understand the environmental conditions at lightning initiation sites.

An Evaluation of Lightning Flash Rate Parameterizations Based on Observations of Colorado Storms during DC3

NASA Astrophysics Data System (ADS)

Basarab, B.; Fuchs, B.; Rutledge, S. A.

2013-12-01

Predicting lightning activity in thunderstorms is important in order to accurately quantify the production of nitrogen oxides (NOx = NO + NO2) by lightning (LNOx). Lightning is an important global source of NOx, and since NOx is a chemical precursor to ozone, the climatological impacts of LNOx could be significant. Many cloud-resolving models rely on parameterizations to predict lightning and LNOx since the processes leading to charge separation and lightning discharge are not yet fully understood. This study evaluates predicted flash rates based on existing lightning parameterizations against flash rates observed for Colorado storms during the Deep Convective Clouds and Chemistry Experiment (DC3). Evaluating lightning parameterizations against storm observations is a useful way to possibly improve the prediction of flash rates and LNOx in models. Additionally, since convective storms that form in the eastern plains of Colorado can be different thermodynamically and electrically from storms in other regions, it is useful to test existing parameterizations against observations from these storms. We present an analysis of the dynamics, microphysics, and lightning characteristics of two case studies, severe storms that developed on 6 and 7 June 2012. This analysis includes dual-Doppler derived horizontal and vertical velocities, a hydrometeor identification based on polarimetric radar variables using the CSU-CHILL radar, and insight into the charge structure using observations from the northern Colorado Lightning Mapping Array (LMA). Flash rates were inferred from the LMA data using a flash counting algorithm. We have calculated various microphysical and dynamical parameters for these storms that have been used in empirical flash rate parameterizations. In particular, maximum vertical velocity has been used to predict flash rates in some cloud-resolving chemistry simulations. We diagnose flash rates for the 6 and 7 June storms using this parameterization and compare to observed flash rates. For the 6 June storm, a preliminary analysis of aircraft observations of storm inflow and outflow is presented in order to place flash rates (and other lightning statistics) in the context of storm chemistry. An approach to a possibly improved LNOx parameterization scheme using different lightning metrics such as flash area will be discussed.

A numerical study on bow shocks around the lightning return stroke channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Qiang, E-mail: cq0405@126.com; Chen, Bin, E-mail: emcchen@163.com; Yi, Yun

2015-03-15

Bow shock structures are important to various hydrodynamics and magnetohydrodynamics (MHD) phenomena in geophysics and astrophysics. The formation and propagation of bow shocks around the lightning return stroke channel are investigated based on the self-similar motion theory and simulated with a two-dimensional Eulerian finite volume resistive radiation MHD code. In this framework, as verification of theoretical models, the evolving structures of many quantities, such as the plasma density, temperature, pressure, shock velocity, and magnetic field, can be obtained, which present all the characteristics of bow shocks in the lightning return stroke processes. The evolution characteristics and the configuration of themore » curved return stroke channels, e.g., the non-ideal effects and the scaling laws, are discussed in detail. The results may have applications for some observed features of the return stroke channels and other phenomena in the lightning discharge plasmas.« less

Mathematical Constraints on the Use of Transmission Line Models for Simulating Initial Breakdown Pulses in Lightning Discharges

NASA Astrophysics Data System (ADS)

da Silva, C. L.; Merrill, R. A.; Pasko, V. P.

2015-12-01

A significant portion of the in-cloud lightning development is observed as a series of initial breakdown pulses (IBPs) that are characterized by an abrupt change in the electric field at a remote sensor. Recent experimental and theoretical studies have attributed this process to the stepwise elongation of an initial lightning leader inside the thunderstorm [da Silva and Pasko, JGR, 120, 4989-5009, 2015, and references therein]. Attempts to visually observe these events are hampered due to the fact that clouds are opaque to optical radiation. Due to this reason, throughout the last decade, a number of researchers have used the so-called transmission line models (also commonly referred to as engineering models), widely employed for return stroke simulations, to simulate the waveshapes of IBPs, and also of narrow bipolar events. The transmission line (TL) model approach is to prescribe the source current dynamics in a certain manner to match the measured E-field change waveform, with the purpose of retrieving key information about the source, such as its height, peak current, size, speed of charge motion, etc. Although the TL matching method is not necessarily physics-driven, the estimated source characteristics can give insights on the dominant length- and time-scales, as well as, on the energetics of the source. This contributes to better understanding of the environment where the onset and early stages of lightning development takes place.In the present work, we use numerical modeling to constrain the number of source parameters that can be confidently inferred from the observed far-field IBP waveforms. We compare different modified TL models (i.e., with different attenuation behaviors) to show that they tend to produce similar waveforms in conditions where the channel is short. We also demonstrate that it is impossible to simultaneously retrieve the speed of source current propagation and channel length from an observed IBP waveform, in contrast to what has been previously done in the literature. Finally, we demonstrate that the simulated field-to-current conversion factor in IBP sources can vary by more than one order of magnitude, making peak current estimates for intracloud lightning processes a challenging task.

Calibration tests on magnetic tape lightning current detectors

NASA Technical Reports Server (NTRS)

Crouch, K. E.

1980-01-01

The low cost, passive, peak lightning current detector (LCD) invented at the NASA/Kennedy Space Center, uses magnetic audio recording tape to sense the magnitude of the peak magnetic field around a conductor carrying lightning currents. Test results show that the length of audio tape erased was linearly related to the peak simulated lightning currents in a round conductor. Accuracies of + or - 10% were shown for measurements made using a stopwatch readout technique to determine the amount of tape erased by the lightning current. The stopwatch technique is a simple, low cost means of obtaining LCD readouts and can be used in the field to obtain immediate results. Where more accurate data are desired, the tape is played and the output recorded on a strip chart, oscilloscope, or some other means so that measurements can be made on that recording. Conductor dimensions, tape holder dimensions, and tape formulation must also be considered to obtain a more accurate result. If the shape of the conductor is other than circular (i.e., angle, channel, H-beam), an analysis of the magnetic field is required to use an LCD, especially at low current levels.

Fly's Eye GLM Simulator Preliminary Validation Analysis

NASA Astrophysics Data System (ADS)

Quick, M. G.; Christian, H. J., Jr.; Blakeslee, R. J.; Stewart, M. F.; Corredor, D.; Podgorny, S.

2017-12-01

As part of the validation effort for the Geostationary Lightning Mapper (GLM) an airborne radiometer array has been fabricated to observe lightning optical emission through the cloud top. The Fly's Eye GLM Simulator (FEGS) is a multi-spectral, photo-electric radiometer array with a nominal spatial resolution of 2 x 2 km and spatial footprint of 10 x 10 km at cloud top. A main 25 pixel array observes the 777.4 nm oxygen emission triplet using an optical passband filter with a 10 nm FWHM, a sampling rate of 100 kHz, and 16 bit resolution. From March to May of 2017 FEGS was flown on the NASA ER-2 high altitude aircraft during the GOES-R Validation Flight Campaign. Optical signatures of lightning were observed during a variety of thunderstorm scenarios while coincident measurements were obtained by GLM and ground based antennae networks. This presentation will describe the preliminary analysis of the FEGS dataset in the context of GLM validation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Qiang, E-mail: cq0405@126.com; Luoyang Electronic Equipment Testing Center, Luoyang 471000; Chen, Bin, E-mail: emcchen@163.com

The Rayleigh-Taylor (R-T) instabilities are important hydrodynamics and magnetohydrodynamics (MHD) phenomena that are found in systems in high energy density physics and normal fluids. The formation and evolution of the R-T instability at channel boundary during back-flow of the lightning return stroke are analyzed using the linear perturbation theory and normal mode analysis methods, and the linear growth rate of the R-T instability in typical condition for lightning return stroke channel is obtained. Then, the R-T instability phenomena of lightning return stroke are simulated using a two-dimensional Eulerian finite volumes resistive radiation MHD code. The numerical results show that themore » evolution characteristics of the R-T instability in the early stage of back-flow are consistent with theoretical predictions obtained by linear analysis. The simulation also yields more evolution characteristics for the R-T instability beyond the linear theory. The results of this work apply to some observed features of the return stroke channel and further advance previous theoretical and experimental work.« less

Assessment of Lightning Transients on a De-Iced Rotor Blade with Predictive Tools and Coaxial Return Measurements

NASA Astrophysics Data System (ADS)

Guillet, S.; Gosmain, A.; Ducoux, W.; Ponçon, M.; Fontaine, G.; Desseix, P.; Perraud, P.

2012-05-01

The increasing use of composite materials in aircrafts primary structures has led to different problematics in the field of safety of flight in lightning conditions. The consequences of this technological mutation, which occurs in a parallel context of extension of electrified critical functions, are addressed by aircraft manufacturers through the enhancement of their available assessment means of lightning transient. On the one hand, simulation tools, provided an accurate description of aircraft design, are today valuable assessment tools, in both predictive and operative terms. On the other hand, in-house test means allow confirmation and consolidation of design office hardening solutions. The combined use of predictive simulation tools and in- house test means offers an efficient and reliable support for all aircraft developments in their various life-time stages. The present paper provides PREFACE research project results that illustrate the above introduced strategy on the de-icing system of the NH90 composite main rotor blade.

Physical mechanism and numerical simulation of the inception of the lightning upward leader

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Qingmin; Lu Xinchang; Shi Wei

2012-12-15

The upward leader is a key physical process of the leader progression model of lightning shielding. The inception mechanism and criterion of the upward leader need further understanding and clarification. Based on leader discharge theory, this paper proposes the critical electric field intensity of the stable upward leader (CEFISUL) and characterizes it by the valve electric field intensity on the conductor surface, E{sub L}, which is the basis of a new inception criterion for the upward leader. Through numerical simulation under various physical conditions, we verified that E{sub L} is mainly related to the conductor radius, and data fitting yieldsmore » the mathematical expression of E{sub L}. We further establish a computational model for lightning shielding performance of the transmission lines based on the proposed CEFISUL criterion, which reproduces the shielding failure rate of typical UHV transmission lines. The model-based calculation results agree well with the statistical data from on-site operations, which show the effectiveness and validity of the CEFISUL criterion.« less

An improved ray theory and transfer matrix method-based model for lightning electromagnetic pulses propagating in Earth-ionosphere waveguide and its applications

NASA Astrophysics Data System (ADS)

Qin, Zilong; Chen, Mingli; Zhu, Baoyou; Du, Ya-ping

2017-01-01

An improved ray theory and transfer matrix method-based model for a lightning electromagnetic pulse (LEMP) propagating in Earth-ionosphere waveguide (EIWG) is proposed and tested. The model involves the presentation of a lightning source, parameterization of the lower ionosphere, derivation of a transfer function representing all effects of EIWG on LEMP sky wave, and determination of attenuation mode of the LEMP ground wave. The lightning source is simplified as an electric point dipole standing on Earth surface with finite conductance. The transfer function for the sky wave is derived based on ray theory and transfer matrix method. The attenuation mode for the ground wave is solved from Fock's diffraction equations. The model is then applied to several lightning sferics observed in central China during day and night times within 1000 km. The results show that the model can precisely predict the time domain sky wave for all these observed lightning sferics. Both simulations and observations show that the lightning sferics in nighttime has a more complicated waveform than in daytime. Particularly, when a LEMP propagates from east to west (Φ = 270°) and in nighttime, its sky wave tends to be a double-peak waveform (dispersed sky wave) rather than a single peak one. Such a dispersed sky wave in nighttime may be attributed to the magneto-ionic splitting phenomenon in the lower ionosphere. The model provides us an efficient way for retrieving the electron density profile of the lower ionosphere and hence to monitor its spatial and temporal variations via lightning sferics.

A Fiber-Optic Current Sensor for Lightning Measurement Applications

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

2015-01-01

An optical-fiber sensor based on Faraday Effect is developed for measuring total lightning electric current. It has many unique capabilities not possible with traditional current sensors. Designed for aircraft installation, the sensor is lightweight, non-conducting, structure-conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can also be used on windmills, lightning towers, and can help validate lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. The broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with about 60 dB dynamic range. Three sensor systems were built with different sensitivities from different laser wavelengths. Operating at 850nm, the first system uses twisted single-mode fiber and has a 150 A - 150 KA range. The second system operates at 1550nm, uses spun polarization maintaining fiber, and can measure 400 A - 400 KA. Both systems were validated with rocket-triggered lightning measurements and achieved excellent results when compared to a resistive shunt. The third system operates at 1310nm, uses spun polarization maintaining fiber, and can measure approximately 300 A - 300 KA. High current measurements up to 200 KA were demonstrated at a commercial lightning test facility. The system was recently installed on an aircraft and flown near icing weather conditions.

A fiber-optic current sensor for lightning measurement applications

NASA Astrophysics Data System (ADS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

2015-05-01

An optical-fiber sensor based on Faraday Effect is developed for measuring total lightning electric current. It has many unique capabilities not possible with traditional current sensors. Designed for aircraft installation, the sensor is lightweight, non-conducting, structure-conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can also be used on windmills, lightning towers, and can help validate lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. The broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with about 60 dB dynamic range. Three sensor systems were built with different sensitivities from different laser wavelengths. Operating at 850nm, the first system uses twisted single-mode fiber and has a 150 A - 150 KA range. The second system operates at 1550nm, uses spun polarization maintaining fiber, and can measure 400 A - 400 KA. Both systems were validated with rocket-triggered lightning measurements and achieved excellent results when compared to a resistive shunt. The third system operates at 1310nm, uses spun polarization maintaining fiber, and can measure approximately 300 A - 300 KA. High current measurements up to 200 KA were demonstrated at a commercial lightning test facility. The system was recently installed on an aircraft and flown near icing weather conditions.

Lightning NOx emissions over the USA constrained by TES ozone observations and the GEOS-Chem model

NASA Astrophysics Data System (ADS)

Jourdain, L.; Kulawik, S. S.; Worden, H. M.; Pickering, K. E.; Worden, J.; Thompson, A. M.

2010-01-01

Improved estimates of NOx from lightning sources are required to understand tropospheric NOx and ozone distributions, the oxidising capacity of the troposphere and corresponding feedbacks between chemistry and climate change. In this paper, we report new satellite ozone observations from the Tropospheric Emission Spectrometer (TES) instrument that can be used to test and constrain the parameterization of the lightning source of NOx in global models. Using the National Lightning Detection (NLDN) and the Long Range Lightning Detection Network (LRLDN) data as well as the HYPSLIT transport and dispersion model, we show that TES provides direct observations of ozone enhanced layers downwind of convective events over the USA in July 2006. We find that the GEOS-Chem global chemistry-transport model with a parameterization based on cloud top height, scaled regionally and monthly to OTD/LIS (Optical Transient Detector/Lightning Imaging Sensor) climatology, captures the ozone enhancements seen by TES. We show that the model's ability to reproduce the location of the enhancements is due to the fact that this model reproduces the pattern of the convective events occurrence on a daily basis during the summer of 2006 over the USA, even though it does not well represent the relative distribution of lightning intensities. However, this model with a value of 6 Tg N/yr for the lightning source (i.e.: with a mean production of 260 moles NO/Flash over the USA in summer) underestimates the intensities of the ozone enhancements seen by TES. By imposing a production of 520 moles NO/Flash for lightning occurring in midlatitudes, which better agrees with the values proposed by the most recent studies, we decrease the bias between TES and GEOS-Chem ozone over the USA in July 2006 by 40%. However, our conclusion on the strength of the lightning source of NOx is limited by the fact that the contribution from the stratosphere is underestimated in the GEOS-Chem simulations.

Implementation of a lightning data assimilation technique in the Weather Research and Forecasting (WRF) model for improving precipitation prediction

NASA Astrophysics Data System (ADS)

Giannaros, Theodore; Kotroni, Vassiliki; Lagouvardos, Kostas

2015-04-01

Lightning data assimilation has been recently attracting increasing attention as a technique implemented in numerical weather prediction (NWP) models for improving precipitation forecasts. In the frame of TALOS project, we implemented a robust lightning data assimilation technique in the Weather Research and Forecasting (WRF) model with the aim to improve the precipitation prediction in Greece. The assimilation scheme employs lightning as a proxy for the presence or absence of deep convection. In essence, flash data are ingested in WRF to control the Kain-Fritsch (KF) convective parameterization scheme (CPS). When lightning is observed, indicating the occurrence of convective activity, the CPS is forced to attempt to produce convection, whereas the CPS may be optionally be prevented from producing convection when no lightning is observed. Eight two-day precipitation events were selected for assessing the performance of the lightning data assimilation technique. The ingestion of lightning in WRF was carried out during the first 6 h of each event and the evaluation focused on the consequent 24 h, constituting a realistic setup that could be used in operational weather forecasting applications. Results show that the implemented assimilation scheme can improve model performance in terms of precipitation prediction. Forecasts employing the assimilation of flash data were found to exhibit more skill than control simulations, particularly for the intense (>20 mm) 24 h rain accumulations. Analysis of results also revealed that the option not to suppress the KF scheme in the absence of observed lightning, leads to a generally better performance compared to the experiments employing the full control of the CPS' triggering. Overall, the implementation of the lightning data assimilation technique is found to improve the model's ability to represent convection, especially in situations when past convection has modified the mesoscale environment in ways that affect the occurrence and evolution of subsequent convection.

On the VHF Source Retrieval Errors Associated with Lightning Mapping Arrays (LMAs)

NASA Technical Reports Server (NTRS)

Koshak, W.

2016-01-01

This presentation examines in detail the standard retrieval method: that of retrieving the (x, y, z, t) parameters of a lightning VHF point source from multiple ground-based Lightning Mapping Array (LMA) time-of-arrival (TOA) observations. The solution is found by minimizing a chi-squared function via the Levenberg-Marquardt algorithm. The associated forward problem is examined to illustrate the importance of signal-to-noise ratio (SNR). Monte Carlo simulated retrievals are used to assess the benefits of changing various LMA network properties. A generalized retrieval method is also introduced that, in addition to TOA data, uses LMA electric field amplitude measurements to retrieve a transient VHF dipole moment source.

Ambient-Light Simulator For Testing Cockpit Displays

NASA Technical Reports Server (NTRS)

Batson, Vernon M.; Gupton, Lawrence E.

1995-01-01

Apparatus provides illumination from outside, through windows and into interior of simulated airplane cockpit. Simulates sunlight, darkness, or lightning on demand. Ambient-lighting simulator surrounds forward section of simulated airplane. Provides control over intensity, color, and diffuseness of solar illumination and of position of Sun relative to airplane. Used to evaluate aircraft-instrumentation display devices under realistic lighting conditions.

Lightning Radio Source Retrieval Using Advanced Lightning Direction Finder (ALDF) Networks

NASA Technical Reports Server (NTRS)

Koshak, William J.; Blakeslee, Richard J.; Bailey, J. C.

1998-01-01

A linear algebraic solution is provided for the problem of retrieving the location and time of occurrence of lightning ground strikes from an Advanced Lightning Direction Finder (ALDF) network. The ALDF network measures field strength, magnetic bearing and arrival time of lightning radio emissions. Solutions for the plane (i.e., no Earth curvature) are provided that implement all of tile measurements mentioned above. Tests of the retrieval method are provided using computer-simulated data sets. We also introduce a quadratic planar solution that is useful when only three arrival time measurements are available. The algebra of the quadratic root results are examined in detail to clarify what portions of the analysis region lead to fundamental ambiguities in source location. Complex root results are shown to be associated with the presence of measurement errors when the lightning source lies near an outer sensor baseline of the ALDF network. In the absence of measurement errors, quadratic root degeneracy (no source location ambiguity) is shown to exist exactly on the outer sensor baselines for arbitrary non-collinear network geometries. The accuracy of the quadratic planar method is tested with computer generated data sets. The results are generally better than those obtained from the three station linear planar method when bearing errors are about 2 deg. We also note some of the advantages and disadvantages of these methods over the nonlinear method of chi(sup 2) minimization employed by the National Lightning Detection Network (NLDN) and discussed in Cummins et al.(1993, 1995, 1998).

Mechanisms of the global electric circuit and lightning variability on the ENSO time scale

NASA Astrophysics Data System (ADS)

Mareev, Evgeny; Volodin, Evgeny; Slyunyaev, Nikolay

2017-04-01

Many studies of lightning activity on the El Niño-Southern Oscillation (ENSO) time scale show increased activity over tropical land areas during the warm El Niño phase (e.g., Satori et al., 2009; Price, 2009). The mechanisms of this variability—particularly in terms of its role in the global electric circuit (GEC)—are still under debate (e.g., Williams and Mareev, 2014). In this study a general circulation model of the atmosphere and ocean INMCM4.0 (Institute of Numerical Mathematics Coupled Model) is used for modelling the GEC variability on the ENSO time scale. The ionospheric potential (IP) and the lightning flash rate are calculated to study regional peculiarities and possible mechanisms of lightning variation. The IP parameterisation is used (Mareev and Volodin, 2014) which takes into account quasi-stationary currents of electrified clouds (including thunderstorms) as principal contributors into the DC global circuit. The account of conductivity variation in the IP parameterisation is suggested based on the approach realised in (Slyunyaev et al., 2014). Comparison of simulation results with the observational data on lightning activity on the ENSO time scale is discussed. Numerical simulations suggest that the inter-annual IP variability is low and does not exceed 1% of the mean value, being tightly correlated with the mean sea surface temperature (SST) in the Pacific Ocean (180W-100W, 5S-5N—El Niño area). The IP maximum corresponds to the SST minimum. This result can be explained taking into account that during El Niño (positive temperature anomaly) precipitations in the equatorial part of the Pacific increase while in other tropic zones including the land areas they decrease. Comparison of simulation results with the observational data on lightning activity on the ENSO time scale is discussed. During the El Niño period in the model, the mean aerosol content in the atmosphere decrease, which is caused by the weakening of the winds over Sahara and South-West Asia lifting dust into the atmosphere. Taking into consideration the decrease in the number of thunderstorms, this does not explain the observed global lightning variation. As another possible explanation for the enhanced El Niño lightning activity, the variation of the atmospheric aerosols and cloud condensation nuclei due to fires is discussed. The work was supported by a grant from the Government of the Russian Federation (contract no. 14.B25.31.0023) and by RFBR grant no. 16-05-01086. References Mareev E.A., Volodin E.M. (2014), Variation of the global electric circuit and ionospheric potential in a general circulation model, Geophys. Res. Lett., V. 41, P. 9009-9016. Sátori G., Williams E., Lemperger I. (2009), Variability of global lightning activity on the ENSO time scale, Atmos. Res., V. 91, P. 500-507. Price C. (2009), Will a drier climate result in a more lightning?, Atmos. Res., V. 91, P. 479-484. Williams E.R., Mareev E.A. (2014), Recent progress on the global electrical circuit, Atmos. Res., V. 135-136, P. 208-227. Slyunyaev N.N., Mareev E.A., Kalinin A.V., Zhidkov A.A. (2014), Influence of large-scale conductivity inhomogeneities in the atmosphere on the global electric circuit, J. Atmos. Sci., V. 71, P. 4382-4396.

The VLF Scattering Pattern of Lightning-Induced Ionospheric Disturbances

NASA Astrophysics Data System (ADS)

Cohen, M.; Golkowski, M.

2016-12-01

Very Low Frequency (VLF) transmitter remote sensing is a well-employed technique to diagnose the impact of lightning on the D-region ionosphere, from the EMP, quasi-static charge, and radiation belt electron precipitation. When lightning disturbs the ionosphere, propagation of VLF (3-30 kHz) narrow-frequency signals through that region are subsequently scattered, which can be detected as transient changes in amplitude and phase at distant receivers. In principle it is possible to then infer the ionospheric disturbance but in practice this is difficult to do reliably. One of the challenges of this process is that VLF perturbations are like snowflakes - no two events are the same. The transmitter-receiver geometry, lightning properties, and ionospheric condition before the event, all impact the VLF scattering. This makes it very difficult, based on case studies which observe only one or two slivers at a time, to infer the scattering pattern of VLF events, and therefore, to infer what happened to the ionosphere. Our aim is to get around that by looking at a huge database of lightning-induced ionospheric disturbances, taken over several years of recordings. We utilize an automatic extraction algorithm to find, identify, and characterize VLF perturbations on a massive scale. From there, we can investigate how the VLF perturbations change as a function of the parameters of the event. If it turns out that there is exists a "canonical" lightning-induced disturbance as a function of geometry and lightning parameters, it will go a long way toward identifying the causative mechanisms and being able to accurately simulate and reproduce any lightning-induced ionospheric disturbance. We present results of our efforts to do just that.

Initiation of Positive Streamers near Uncharged Ice Hydrometeors in the Thundercloud Field

NASA Astrophysics Data System (ADS)

Babich, L. P.; Bochkov, E. I.

2018-05-01

Since the threshold electric field required for breakdown of air is much higher than the maximum field strength measured in thunderstorm clouds, the problem of lightning initiation still remains unsolved. According to the popular hypothesis, lightning can be initiated by a streamer discharge in the field enhanced near a hydrometeor. To verify the adequacy of this hypothesis, the development of a positive streamer propagating along the thunderstorm electric field in the vicinity of an ice needle at an air pressure corresponding to an altitude of 5 km (which is typical of the lightning initiation conditions) was simulated numerically. The hydrometeor dimensions are determined at which streamers can be initiated at different strengths of the thunderstorm electric field.

The interaction with the lower ionosphere of electromagnetic pulses from lightning: Excitation of optical emissions

NASA Technical Reports Server (NTRS)

Taranenko, Y. N.; Inan, U. S.; Bell, T. F.

1993-01-01

A self consistent and fully kinetic simulation of the interaction of lightning radiated electromagnetic (EM) pulses with the nighttime lower ionosphere indicates that optical emissions observable with conventional instruments would be excited. For example, emissions of the 1st and 2nd positive bands of N2 occur at rates reaching 7 x 10(exp 7) and 10(exp 7) cu cm/s respectively at 92 km altitude for a lightning discharge with an electric field E(sub 100) = 20 V/m (normalized to a 100 km distance). The maximum height integrated intensities of these emissions are 4 x 10(exp 7) and 6 x 10(exp 6) R respectively, lasting for approx. 50 micrometers.

Analysis of lightning field changes produced by Florida thunderstorms

NASA Technical Reports Server (NTRS)

Koshak, William John

1991-01-01

A new method is introduced for inferring the charges deposited in a lightning flash. Lightning-caused field changes (delta E's) are described by a more general volume charge distribution than is defined on a large cartesian grid system centered above the measuring networks. It is shown that a linear system of equations can be used to relate delta E's at the ground to the values of charge on this grid. It is possible to apply more general physical constraints to the charge solutions, and it is possible to access the information content of the delta E data. Computer-simulated delta E inversions show that the location and symmetry of the charge retrievals are usually consistent with the known test sources.

LSP Composite Susbtrate Manufacturing Processing Guide

NASA Technical Reports Server (NTRS)

Kovach, Daniel J.; Griess, Kenneth H.

2013-01-01

This document is intended to define Carbon Fiber Reinforced Plastic (CFRP) test panel configurations that can be employed for the purposes of evaluating the protection capabilities of Lightning Strike Protection (LSP) materials developed by the Aerospace Industry. The configurations are intended to provide consistent behavior in their response to simulated lightning strikes at pre-defined levels when tested by a capable vendor according to a test procedure written to enable consistent results (ref section 2.1.2). In response to an attachment of a simulated lightning strike on a CFRP panel, one can expect to see various levels of ablation and delamination, both through the thickness of the panel and with respect to the amount of panel surface area that exhibits damage. Panel configurations defined in this document include: An "unprotected" configuration 128694-1 (ref section 4.1), consisting of a cured CFRP laminate stackup of tape and fabric prepregs, coated with a typical aerospace primer and paint finishing scheme, attached to aluminum grounding bars intended to draw electrical current from the lightning attachment point to the panel edges and thus to ground. A "protected" configuration 128694-2 (ref section 4.1), wherein a layer of an LSP material form often used in the Aerospace Industry is included in the laminate stackup prior to cure. The CFRP materials, finishes and grounding arrangement for ths configuration are the same as for the "unprotected" configuration.

High Speed Video Observations of Natural Lightning and Their Implications to Fractal Description of Lightning

NASA Astrophysics Data System (ADS)

Liu, N.; Tilles, J.; Boggs, L.; Bozarth, A.; Rassoul, H.; Riousset, J. A.

2016-12-01

Recent high speed video observations of triggered and natural lightning flashes have significantly advanced our understanding of lightning initiation and propagation. For example, they have helped resolve the initiation of lightning leaders [Stolzenburg et al., JGR, 119, 12198, 2014; Montanyà et al, Sci. Rep., 5, 15180, 2015], the stepping of negative leaders [Hill et al., JGR, 116, D16117, 2011], the structure of streamer zone around the leader [Gamerota et al., GRL, 42, 1977, 2015], and transient rebrightening processes occurring during the leader propagation [Stolzenburg et al., JGR, 120, 3408, 2015]. We started an observational campaign in the summer of 2016 to study lightning by using a Phantom high-speed camera on the campus of Florida Institute of Technology, Melbourne, FL. A few interesting natural cloud-to-ground and intracloud lightning discharges have been recorded, including a couple of 8-9 stroke flashes, high peak current flashes, and upward propagating return stroke waves from ground to cloud. The videos show that the propagation of the downward leaders of cloud-to-ground lightning discharges is very complex, particularly for the high-peak current flashes. They tend to develop as multiple branches, and each of them splits repeatedly. For some cases, the propagation characteristics of the leader, such as speed, are subject to sudden changes. In this talk, we present several selected cases to show the complexity of the leader propagation. One of the effective approaches to characterize the structure and propagation of lightning leaders is the fractal description [Mansell et al., JGR, 107, 4075, 2002; Riousset et al., JGR, 112, D15203, 2007; Riousset et al., JGR, 115, A00E10, 2010]. We also present a detailed analysis of the high-speed images of our observations and formulate useful constraints to the fractal description. Finally, we compare the obtained results with fractal simulations conducted by using the model reported in [Riousset et al., 2007, 2010].

Lightning and Other Influences On Tropical Tropospheric Ozone: Empirical Studies of Covariation

NASA Technical Reports Server (NTRS)

Chatfield, Robert B.; Guan, Hong; Hudson, Robert D.; Witte, Jacquelyne C.

2003-01-01

Tropical and subtropical tropospheric ozone are important radiatively active species, with particularly large effects in the upper third of the troposphere. Temporal variability of O3 has proved difficult to simulate day by day in process models. Thus, individual roles of lightning, biomass burning, and other pollution in providing precursor NO(x), radicals, and chain carriers (CO, hydrocarbons) remain unquantified by simulation, and it is theoretically reasonable that individual roles are magnified by a joint synergy. We use wavelet analysis and Burg-algorithm maximum entropy spectral analyses to describe time-scales and correlation of ozone with proxies for processes controlling its concentration. Our empirical studies link time variations apparent in several datasets: the SHADOZ (Southern Hemisphere Additional Ozonesondes) network stations (Nairobi, Fiji), and auxiliary series with power to explain ozone-determining processes, with some interpretation based on the TTO (Tropical Tropospheric Ozone) product derived from TOMS (the Total Ozone Mapping Spectrometer). The auxiliary series are The OTD/LIS(Optical Transient Detector/Lightning Imaging Sensor) measurements of the lightning NO(x) source, the OLR (Outgoing Longwave Radiation)measurement of high-topped clouds, and standard meteorological variables from the United States NCEP (National Centers for Environmental Prediction) and Data Assimilation Office analyses. Concentrating on equatorial ozone, we compare the statistical evidence on the variability of tropospheric ozone. Important variations occur on approximately two-week, two-month (Madden-Julian Oscillation) and annual scales, and relations with OLR suggest controls associated with continental clouds. Hence we are now using the Lightning Imaging Sensor data set to indicate NO(x) sources. We report initial results defining relative roles of the process mentioned affecting O3 using their covariance properties.

DEVELOPMENT OF A METHOD FOR THE OBSERVATION OF LIGHTNING IN PROTOPLANETARY DISKS USING ION LINES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muranushi, Takayuki; Akiyama, Eiji; Inutsuka, Shu-ichiro

2015-12-20

In this paper, we propose observational methods for detecting lightning in protoplanetary disks. We do so by calculating the critical electric field strength in the lightning matrix gas (LMG), the parts of the disk where the electric field is strong enough to cause lightning. That electric field accelerates multiple positive ion species to characteristic terminal velocities. In this paper, we present three distinct discharge models with corresponding critical electric fields. We simulate the position–velocity diagrams and the integrated emission maps for the models. We calculate the measure-of-sensitivity values for detection of the models and for distinguishing between the models. Atmore » the distance of TW Hya (54 pc), LMG that occupies 2π in azimuth and has 25 AU < r < 50 AU is detectable at 1200σ to 4000σ. The lower limits of the radii of 5σ-detectable LMG clumps are between 1.6 AU and 5.3 AU, depending on the models.« less

Impacts of WRF lightning assimilation on offline CMAQ simulations

EPA Science Inventory

Deep convective clouds vertically redistribute trace gases and aerosols and also provide a source for scavenging, aqueous phase chemistry, and wet deposition, making them important to air quality.? Regional air quality simulations are typically driven by meteorological models tha...

Influence of the North American monsoon on Southern California tropospheric ozone levels during summer in 2013 and 2014

NASA Astrophysics Data System (ADS)

Granados-Muñoz, Maria Jose; Johnson, Matthew S.; Leblanc, Thierry

2017-06-01

The impact of the North American (NA) monsoon on tropospheric ozone variability in Southern California is investigated using lidar measurements at Jet Propulsion Laboratory-Table Mountain Facility, California, and the chemical-transport model GEOS-Chem. Routine lidar observations obtained in July-August 2013-2014 reveal a consistent ozone enhancement of 23 ppbv in the free troposphere (6-9 km), when ozone-rich air is transported along the western edge of the upper level anticyclone associated with the NA monsoon from regions where maximum lightning-induced NOx production occurs. When the high-pressure system shifts to the southeast, a zonal westerly flow of the air parcels reaching the Table Mountain Facility (TMF) occurs, prohibiting the lightning-induced ozone enhanced air to reach TMF. This modulation of tropospheric ozone by the position of the NA monsoon anticyclone could have implications on long-term ozone trends associated with our changing climate, due to the expected widening of the tropical belt affecting the strength and position of the anticyclone.

Common Practice Lightning Strike Protection Characterization Technique to Quantify Damage Mechanisms on Composite Substrates

NASA Technical Reports Server (NTRS)

Szatkowski, George N.; Dudley, Kenneth L.; Koppen, Sandra V.; Ely, Jay J.; Nguyen, Truong X.; Ticatch, Larry A.; Mielnik, John J.; Mcneill, Patrick A.

2013-01-01

To support FAA certification airworthiness standards, composite substrates are subjected to lightning direct-effect electrical waveforms to determine performance characteristics of the lightning strike protection (LSP) conductive layers used to protect composite substrates. Test results collected from independent LSP studies are often incomparable due to variability in test procedures & applied practices at different organizations, which impairs performance correlations between different LSP data sets. Under a NASA supported contract, The Boeing Company developed technical procedures and documentation as guidance in order to facilitate a test method for conducting universal common practice lightning strike protection test procedures. The procedures obtain conformity in future lightning strike protection evaluations to allow meaningful performance correlations across data sets. This universal common practice guidance provides the manufacturing specifications to fabricate carbon fiber reinforced plastic (CFRP) test panels, including finish, grounding configuration, and acceptable methods for pretest nondestructive inspection (NDI) and posttest destructive inspection. The test operations guidance elaborates on the provisions contained in SAE ARP5416 to address inconsistencies in the generation of damage protection performance data, so as to provide for maximum achievable correlation across capable lab facilities. In addition, the guidance details a direct effects test bed design to aid in quantification of the multi-physical phenomena surrounding a lightning direct attachment supporting validation data requirements for the development of predictive computational modeling. The lightning test bed is designed to accommodate a repeatable installation procedure to secure the test panel and eliminate test installation uncertainty. It also facilitates a means to capture the electrical waveform parameters in 2 dimensions, along with the mechanical displacement and thermal heating parameters which occur during lightning attachment. Following guidance defined in the universal common practice LSP test documents, protected and unprotected CFRP panels were evaluated at 20, 40 and 100KAmps. This report presents analyzed data demonstrating the scientific usefulness of the common practice approach. Descriptions of the common practice CFRP test articles, LSP test bed fixture, and monitoring techniques to capture the electrical, mechanical and thermal parameters during lightning attachment are presented here. Two methods of measuring the electrical currents were evaluated, inductive current probes and a newly developed fiberoptic sensor. Two mechanical displacement methods were also examined, optical laser measurement sensors and a digital imaging correlation camera system. Recommendations are provided to help users implement the common practice test approach and obtain LSP test characterizations comparable across data sets.

Computer Programs for Prediction of Lightning Induced Voltages in Aircraft Electrical Circuits

DTIC Science & Technology

1975-04-01

8217-Mnnmn " ■*> i ■ : mmmmim*mmemmmMmmmmmam*t*ammi m ■■>■ ■ ,-,.->»^~—~—-. ■ - m^m Test techniques and equipment have been designed for subjecting com...are still on the drawing board, when there is as yet no aircraft on which to run tests . To fulfill this need, a program was initiated by the Air...aluated by full-scale simulated lightning tests of the external assemblies in question. Government specifications for some of these devices or

Modelling digital thunder

NASA Astrophysics Data System (ADS)

Blanco, Francesco; La Rocca, Paola; Petta, Catia; Riggi, Francesco

2009-01-01

An educational model simulation of the sound produced by lightning in the sky has been employed to demonstrate realistic signatures of thunder and its connection to the particular structure of the lightning channel. Algorithms used in the past have been revisited and implemented, making use of current computer techniques. The basic properties of the mathematical model, together with typical results and suggestions for additional developments are discussed. The paper is intended as a teaching aid for students and teachers in the context of introductory physics courses at university level.

Lightning protection using energized Franklin rods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdel-Salam, M.; Al-Abdul-Latif, U.

1995-12-31

In this paper, the onset criterion of the upward streamers from an energized Franklin rod is formulated as a function of the geometry of the rod and the height and current of the downward leader. The electric field in the vicinity of the lightning rod is calculated using the charge simulation technique. The dependency of the radius of protection on the amplitude of the pulse voltage applied to Franklin rod, the downward leader current and the tip radius and height of the rod is investigated.

KSC-04PD-1319

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. Sitting in front of the open hatch into Discovery, which is in the Orbiter Processing Facility, Mike Bolt (left), NASAs Jack Legere (center front) and Jay Feaster (right) display the Stanley Cup. Feaster is general manager of the Tampa Bay Lightning, who won the cup in 2004, and Bolt is keeper of the cup. Legere is NASA Quality Assurance specialist for the Shuttle Program. The cup was also briefly available for viewing by employees in the KSC Training Auditorium. Feaster brought the cup to KSC while on a tour. The Stanley Cup weighs 35 pounds and is more than 100 years old. The Lightning will be added to the cup in September.

Simulation of radiation from lightning return strokes - The effects of tortuosity

NASA Technical Reports Server (NTRS)

Levine, D. M.; Meneghini, R.

1978-01-01

A Monte Carlo simulation has been developed for the electromagnetic fields radiated from a tortuous lightning channel. This was done using a piecewise linear model for the channel and employing for each element the field radiated by a traveling wave on an arbitrarily oriented filament over a conducting plane. The simulation reproduces experimental data reasonably well and has been used to study the effects of tortuosity on the fields radiated by return strokes. Tortuosity can significantly modify the radiated waveform, tending to render it less representative of the current pulse and more nearly unipolar than one would expect based on the theory for a long straight channel. In the frequency domain the effect of tortuosity is an increase in high frequency energy as compared with an equivalent straight channel. The extent of this increase depends on the mean length of the elements comprising the channel and can be significant.

Statistical-dynamical modeling of the cloud-to-ground lightning activity in Portugal

NASA Astrophysics Data System (ADS)

Sousa, J. F.; Fragoso, M.; Mendes, S.; Corte-Real, J.; Santos, J. A.

2013-10-01

The present study employs a dataset of cloud-to-ground discharges over Portugal, collected by the Portuguese lightning detection network in the period of 2003-2009, to identify dynamically coherent lightning regimes in Portugal and to implement a statistical-dynamical modeling of the daily discharges over the country. For this purpose, the high-resolution MERRA reanalysis is used. Three lightning regimes are then identified for Portugal: WREG, WREM and SREG. WREG is a typical cold-core cut-off low. WREM is connected to strong frontal systems driven by remote low pressure systems at higher latitudes over the North Atlantic. SREG is a combination of an inverted trough and a mid-tropospheric cold-core nearby Portugal. The statistical-dynamical modeling is based on logistic regressions (statistical component) developed for each regime separately (dynamical component). It is shown that the strength of the lightning activity (either strong or weak) for each regime is consistently modeled by a set of suitable dynamical predictors (65-70% of efficiency). The difference of the equivalent potential temperature in the 700-500 hPa layer is the best predictor for the three regimes, while the best 4-layer lifted index is still important for all regimes, but with much weaker significance. Six other predictors are more suitable for a specific regime. For the purpose of validating the modeling approach, a regional-scale climate model simulation is carried out under a very intense lightning episode.

Data Retrieval Algorithms for Validating the Optical Transient Detector and the Lightning Imaging Sensor

NASA Technical Reports Server (NTRS)

Koshak, W. J.; Blakeslee, R. J.; Bailey, J. C.

2000-01-01

A linear algebraic solution is provided for the problem of retrieving the location and time of occurrence of lightning ground strikes from an Advanced Lightning Direction Finder (ALDF) network. The ALDF network measures field strength, magnetic bearing, and arrival time of lightning radio emissions. Solutions for the plane (i.e., no earth curvature) are provided that implement all of these measurements. The accuracy of the retrieval method is tested using computer-simulated datasets, and the relative influence of bearing and arrival time data an the outcome of the final solution is formally demonstrated. The algorithm is sufficiently accurate to validate NASA:s Optical Transient Detector and Lightning Imaging Sensor. A quadratic planar solution that is useful when only three arrival time measurements are available is also introduced. The algebra of the quadratic root results are examined in detail to clarify what portions of the analysis region lead to fundamental ambiguities in sc)iirce location, Complex root results are shown to be associated with the presence of measurement errors when the lightning source lies near an outer sensor baseline of the ALDF network. For arbitrary noncollinear network geometries and in the absence of measurement errors, it is shown that the two quadratic roots are equivalent (no source location ambiguity) on the outer sensor baselines. The accuracy of the quadratic planar method is tested with computer-generated datasets, and the results are generally better than those obtained from the three-station linear planar method when bearing errors are about 2 deg.

Modeling of X-ray Images and Energy Spectra Produced by Stepping Lightning Leaders

NASA Astrophysics Data System (ADS)

Xu, Wei; Marshall, Robert A.; Celestin, Sebastien; Pasko, Victor P.

2017-11-01

Recent ground-based measurements at the International Center for Lightning Research and Testing (ICLRT) have greatly improved our knowledge of the energetics, fluence, and evolution of X-ray emissions during natural cloud-to-ground (CG) and rocket-triggered lightning flashes. In this paper, using Monte Carlo simulations and the response matrix of unshielded detectors in the Thunderstorm Energetic Radiation Array (TERA), we calculate the energy spectra of X-rays as would be detected by TERA and directly compare with the observational data during event MSE 10-01. The good agreement obtained between TERA measurements and theoretical calculations supports the mechanism of X-ray production by thermal runaway electrons during the negative corona flash stage of stepping lightning leaders. Modeling results also suggest that measurements of X-ray bursts can be used to estimate the approximate range of potential drop of lightning leaders. Moreover, the X-ray images produced during the leader stepping process in natural negative CG discharges, including both the evolution and morphological features, are theoretically quantified. We show that the compact emission pattern as recently observed in X-ray images is likely produced by X-rays originating from the source region, and the diffuse emission pattern can be explained by the Compton scattering effects.

First experimental observations on melting and chemical modification of volcanic ash during lightning interaction.

PubMed

Mueller, S P; Helo, C; Keller, F; Taddeucci, J; Castro, J M

2018-01-23

Electrification in volcanic ash plumes often leads to syn-eruptive lightning discharges. High temperatures in and around lightning plasma channels have the potential to chemically alter, re-melt, and possibly volatilize ash fragments in the eruption cloud. In this study, we experimentally simulate temperature conditions of volcanic lightning in the laboratory, and systematically investigate the effects of rapid melting on the morphology and chemical composition of ash. Samples of different size and composition are ejected towards an artificially generated electrical arc. Post-experiment ash morphologies include fully melted spheres, partially melted particles, agglomerates, and vesiculated particles. High-speed imaging reveals various processes occurring during the short lightning-ash interactions, such as particle melting and rounding, foaming, and explosive particle fragmentation. Chemical analyses of the flash-melted particles reveal considerable bulk loss of Cl, S, P and Na through thermal vaporization. Element distribution patterns suggest convection as a key process of element transport from the interior of the melt droplet to rim where volatiles are lost. Modeling the degree of sodium loss delivers maximum melt temperatures between 3290 and 3490 K. Our results imply that natural lighting strikes may be an important agent of syn-eruptive morphological and chemical processing of volcanic ash.

A comparison study of convective and microphysical parameterization schemes associated with lightning occurrence in southeastern Brazil using the WRF model

NASA Astrophysics Data System (ADS)

Zepka, G. D.; Pinto, O.

2010-12-01

The intent of this study is to identify the combination of convective and microphysical WRF parameterizations that better adjusts to lightning occurrence over southeastern Brazil. Twelve thunderstorm days were simulated with WRF model using three different convective parameterizations (Kain-Fritsch, Betts-Miller-Janjic and Grell-Devenyi ensemble) and two different microphysical schemes (Purdue-Lin and WSM6). In order to test the combinations of parameterizations at the same time of lightning occurrence, a comparison was made between the WRF grid point values of surface-based Convective Available Potential Energy (CAPE), Lifted Index (LI), K-Index (KI) and equivalent potential temperature (theta-e), and the lightning locations nearby those grid points. Histograms were built up to show the ratio of the occurrence of different values of these variables for WRF grid points associated with lightning to all WRF grid points. The first conclusion from this analysis was that the choice of microphysics did not change appreciably the results as much as different convective schemes. The Betts-Miller-Janjic parameterization has generally worst skill to relate higher magnitudes for all four variables to lightning occurrence. The differences between the Kain-Fritsch and Grell-Devenyi ensemble schemes were not large. This fact can be attributed to the similar main assumptions used by these schemes that consider entrainment/detrainment processes along the cloud boundaries. After that, we examined three case studies using the combinations of convective and microphysical options without the Betts-Miller-Janjic scheme. Differently from the traditional verification procedures, fields of surface-based CAPE from WRF 10 km domain were compared to the Eta model, satellite images and lightning data. In general the more reliable convective scheme was Kain-Fritsch since it provided more consistent distribution of the CAPE fields with respect to satellite images and lightning data.

Open Circuit Resonant (SansEC) Sensor Technology for Lightning Mitigation and Damage Detection and Diagnosis for Composite Aircraft Applications

NASA Technical Reports Server (NTRS)

Szatkowski, George N.; Dudley, Kenneth L.; Smith, Laura J.; Wang, Chuantong; Ticatch, Larry A.

2014-01-01

Traditional methods to protect composite aircraft from lightning strike damage rely on a conductive layer embedded on or within the surface of the aircraft composite skin. This method is effective at preventing major direct effect damage and minimizes indirect effects to aircraft systems from lightning strike attachment, but provides no additional benefit for the added parasitic weight from the conductive layer. When a known lightning strike occurs, the points of attachment and detachment on the aircraft surface are visually inspected and checked for damage by maintenance personnel to ensure continued safe flight operations. A new multi-functional lightning strike protection (LSP) method has been developed to provide aircraft lightning strike protection, damage detection and diagnosis for composite aircraft surfaces. The method incorporates a SansEC sensor array on the aircraft exterior surfaces forming a "Smart skin" surface for aircraft lightning zones certified to withstand strikes up to 100 kiloamperes peak current. SansEC sensors are open-circuit devices comprised of conductive trace spiral patterns sans (without) electrical connections. The SansEC sensor is an electromagnetic resonator having specific resonant parameters (frequency, amplitude, bandwidth & phase) which when electromagnetically coupled with a composite substrate will indicate the electrical impedance of the composite through a change in its resonant response. Any measureable shift in the resonant characteristics can be an indication of damage to the composite caused by a lightning strike or from other means. The SansEC sensor method is intended to diagnose damage for both in-situ health monitoring or ground inspections. In this paper, the theoretical mathematical framework is established for the use of open circuit sensors to perform damage detection and diagnosis on carbon fiber composites. Both computational and experimental analyses were conducted to validate this new method and system for aircraft composite damage detection and diagnosis. Experimental test results on seeded fault damage coupons and computational modeling simulation results are presented. This paper also presents the shielding effectiveness along with the lightning direct effect test results from several different SansEC LSP and baseline protected and unprotected carbon fiber reinforced polymer (CFRP) test panels struck at 40 and 100 kiloamperes following a universal common practice test procedure to enable damage comparisons between SansEC LSP configurations and common practice copper mesh LSP approaches. The SansEC test panels were mounted in a LSP test bed during the lightning test. Electrical, mechanical and thermal parameters were measured during lightning attachment and are presented with post test nondestructive inspection comparisons. The paper provides correlational results between the SansEC sensors computed electric field distribution and the location of the lightning attachment on the sensor trace and visual observations showing the SansEC sensor's affinity for dispersing the lightning attachment.

Radar Differential Phase Signatures of Ice Orientation for the Prediction of Lightning Initiation and Cessation

NASA Technical Reports Server (NTRS)

Carey, L.D.; Petersen, W.A.; Deierling, W.

2009-01-01

The majority of lightning-related casualties typically occur during thunderstorm initiation (e.g., first flash) or dissipation (e.g., last flash). The physics of electrification and lightning production during thunderstorm initiation is fairly well understood. As such, the literature includes a number of studies presenting various radar techniques (using reflectivity and, if available, other dual-polarimetric parameters) for the anticipation of initial electrification and first lightning flash. These radar techniques have shown considerable skill at forecasting first flash. On the other hand, electrical processes and lightning production during thunderstorm dissipation are not nearly as well understood and few, if any, successful techniques have been developed to anticipate the last flash and subsequent cessation of lightning. One promising approach involves the use of dual-polarimetric radar variables to infer the presence of oriented ice crystals in lightning producing storms. In the absence of strong vertical electric fields, ice crystals fall with their largest (semi-major) axis in the horizontal associated with gravitational and aerodynamic forces. In thunderstorms, strong vertical electric fields (100-200 kV m(sup -1)) have been shown to orient small (less than 2 mm) ice crystals such that their semi-major axis is vertical (or nearly vertical). After a lightning flash, the electric field is typically relaxed and prior radar research suggests that ice crystals rapidly resume their preferred horizontal orientation. In active thunderstorms, the vertical electric field quickly recovers and the ice crystals repeat this cycle of orientation for each nearby flash. This change in ice crystal orientation from primarily horizontal to vertical during the development of strong vertical electric fields prior to a lightning flash forms the physical basis for anticipating lightning initiation and, potentially, cessation. Research has shown that radar reflectivity (Z) and other co-polar back-scattering radar measurements like differential reflectivity (Z(sub dr)) typically measured by operational dual-polarimetric radars are not sensitive to these changes in ice crystal orientation. However, prior research has demonstrated that oriented ice crystals cause significant propagation effects that can be routinely measured by most dual-polarimetric radars from X-band (3 cm) to S-band (10 cm) wavelengths using the differential propagation phase shift (often just called differential phase, phi(sub dp)) or its range derivative, the specific differential phase (K(sub dp)). Advantages of the differential phase include independence from absolute or relative power calibration, attenuation, differential attenuation and relative insensitivity to ground clutter and partial beam occultation effects (as long as the signal remains above noise). In research mode, these sorts of techniques have been used to anticipate initial cloud electrification, lightning initiation, and cessation. In this study, we develop a simplified model of ice crystal size, shape, orientation, dielectric, and associated radar scattering and propagation effects in order to simulate various idealized scenarios of ice crystals responding to a hypothetical electric field and their dual-polarimetric radar signatures leading up to lightning initiation and particularly cessation. The sensitivity of the K(sub dp) ice orientation signature to various ice properties and radar wavelength will be explored. Since K(sub dp) is proportional to frequency in the Rayleigh- Gans scattering regime, the ice orientation signatures should be more obvious at higher (lower) frequencies (wavelengths). As a result, simulations at radar wavelengths from 10 cm down to 1 cm (Ka-band) will be conducted. Resonance effects will be considered using the T-matrix method. Since most K(sub dp) Vbased observations have been shown at S-band, we will present ice orientation signatures from C-band (UAH/NASA ARMOR) and X-bd (UAH MAX) dual-polarimetric radars located in Northern Alabama. Issues related to optimal radar scanning for the detection of oriented ice will be discussed. Preliminary suggestions on how these differential phase signatures of oriented ice could contribute to lightning initiation and cessation algorithms will be presented.

Theoretical and experimental study of the formation conditions of stepped leaders in negative flashes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Shijun, E-mail: sj-xie@163.com; State Key Laboratory of Control and Simulation of Power System and Generation Equipment, Department of Electrical Engineering, Tsinghua University, Beijing 100084; Zeng, Rong

2015-08-15

Natural lightning flashes are stochastic and uncontrollable, and thus, it is difficult to observe the formation process of a downward negative stepped leader (NSL) directly and in detail. This situation has led to some dispute over the actual NSL formation mechanism, and thus has hindered improvements in the lightning shielding analysis model. In this paper, on the basis of controllable long air gap discharge experiments, the formation conditions required for NSLs in negative flashes have been studied. First, a series of simulation experiments on varying scales were designed and carried out. The NSL formation processes were observed, and several ofmore » the characteristic process parameters, including the scale, the propagation velocity, and the dark period, were obtained. By comparing the acquired formation processes and the characteristic parameters with those in natural lightning flashes, the similarity between the NSLs in the simulation experiments and those in natural flashes was proved. Then, based on the local thermodynamic equation and the space charge estimation method, the required NSL formation conditions were deduced, and the space background electric field (E{sub b}) was proposed as the primary parameter for NSL formation. Finally, the critical value of E{sub b} required for the formation of NSLs in natural flashes was determined to be approximately 75 kV/m by extrapolation of the results of the simulation experiments.« less

Laboratory modeling and analysis of aircraft-lightning interactions

NASA Technical Reports Server (NTRS)

Turner, C. D.; Trost, T. F.

1982-01-01

Modeling studies of the interaction of a delta wing aircraft with direct lightning strikes were carried out using an approximate scale model of an F-106B. The model, which is three feet in length, is subjected to direct injection of fast current pulses supplied by wires, which simulate the lightning channel and are attached at various locations on the model. Measurements are made of the resulting transient electromagnetic fields using time derivative sensors. The sensor outputs are sampled and digitized by computer. The noise level is reduced by averaging the sensor output from ten input pulses at each sample time. Computer analysis of the measured fields includes Fourier transformation and the computation of transfer functions for the model. Prony analysis is also used to determine the natural frequencies of the model. Comparisons of model natural frequencies extracted by Prony analysis with those for in flight direct strike data usually show lower damping in the in flight case. This is indicative of either a lightning channel with a higher impedance than the wires on the model, only one attachment point, or short streamers instead of a long channel.

The influence of lightning activity and anthropogenic factors on large-scale characteristics of natural fires

NASA Astrophysics Data System (ADS)

Eliseev, A. V.; Mokhov, I. I.; Chernokulsky, A. V.

2017-01-01

A module for simulating of natural fires (NFs) in the climate model of the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM), is extended with respect to the influence of lightning activity and population density on the ignition frequency and fire suppression. The IAP RAS CM is used to perform numerical experiments in accordance with the conditions of the project that intercompares climate models, CMIP5 (Coupled Models Intercomparison Project, phase 5). The frequency of lightning flashes was assigned in accordance with the LIS/OTD satellite data. In the calculations performed, anthropogenic ignitions play an important role in NF occurrences, except for regions at subpolar latitudes and, to a lesser degree, tropical and subtropical regions. Taking into account the dependence of fire frequency on lightning activity and population density intensifies the influence of characteristics of natural fires on the climate changes in tropics and subtropics as compared to the version of the IAP RAS CM that does not take the influence of ignition sources on the large-scale characteristics of NFs into consideration.

Damage to metallic samples produced by measured lightning currents

NASA Technical Reports Server (NTRS)

Fisher, Richard J.; Schnetzer, George H.

1991-01-01

A total of 10 sample disks of 2024-T3 aluminum and 4130 ferrous steel were exposed to rocket-triggered lightning currents at the Kennedy Space Center test site. The experimental configuration was arranged so that the samples were not exposed to the preliminary streamer, wire-burn, or following currents that are associated with an upward-initiated rocket-triggered flash but which are atypical of naturally initiated lightning. Return-stroke currents and continuing currents actually attaching to the sample were measured, augmented by close-up video recordings of approximately 3 feet of the channel above the sample and by 16-mm movies with 5-ms resolution. From these data it was possible to correlate individual damage spots with streamer, return-stroke, and continuing currents that produced them. Substantial penetration of 80-mil aluminum was produced by a continuing current of submedian amplitude and duration, and full penetration of a 35-mil steel sample occurred under an eightieth percentile continuing current. The primary purpose of the data acquired in these experiments is for use in improving and quantifying the fidelity of laboratory simulations of lightning burnthrough.

Investigation on Improvements in Lightning Retest Criteria for Spacecraft

NASA Technical Reports Server (NTRS)

Terseck, Alex; Trout, Dawn

2016-01-01

Spacecraft are generally protected from a direct strike by launch the vehicle and ground structures, but protocols to evaluate the impact of nearby strikes are not consistent. Often spacecraft rely on the launch vehicle constraints to trigger a retest, but launch vehicles can typically evaluate the impact of a strike within minutes while spacecraft evaluation times can be on the order of hours or even days. For launches at the Kennedy Space Center where lightning activity is among the highest in the United States, this evaluation related delay could be costly with the possibility of missing the launch window altogether. This paper evaluated available data from local lightning measurements systems and computer simulations to predict the coupled effect from various nearby strikes onto a typical payload umbilical. Recommendations are provided to reduce the typical trigger criteria and costly delays.

Development Status of Optical and Electromagnetic Instruments onboard JEM-GLIMS

NASA Astrophysics Data System (ADS)

Sato, Mitsuteru; Ushio, Tomoo; Morimoto, Takeshi; Suzuki, Makoto; Yamazaki, Atsushi; Ishida, Ryohei; Takahashi, Yukihiro; Hobara, Yasuhide; Sakamoto, Yuji; Yoshita, Kengo

In order to study the generation mechanism of Transient Luminous Events (TLEs), global oc-currence rates and distributions of lightning and TLEs, and the relationship between lightning, TLEs and Terrestrial Gamma-ray Flashes (TGFs), we will carry out the lightning and TLE observation at Exposed Facility of Japanese Experiment Module (JEM-EF) of International Space Station (ISS). In this mission named JEM-GLIMS (Global Lightning and sprIte Mea-surementS on JEM-EF) two kinds of optical instruments and two sets of radio receivers will be integrated into the Multi mission Consolidated Equipment (MCE) which is the bus system and will be installed at JEM-EF. The optical instruments consist of two wide FOV CMOS cameras and six wide FOV photometers, and all these optical instruments are pointed to the nadir direction. CMOS cameras named LSI (Lightning and Sprite Imager) use the STAR-250 device as a detector, which has 512x512 pixels and 25x25 µm pixel size, and have 28.3x28.3 deg. FOV. One CMOS camera with a wide band filter (730-830 nm) mainly measures lightning emission, while another camera with a narrowband filter (766+/-6 nm) mainly measures TLE emission. Five of six photometers named as PH have 42.7 deg. FOV and use photomultiplier tube (PMT) as a photon detector. They equip band-pass filters (150-280 nm, 316+/-5 nm, 337+/-5 nm, 392+/-5 nm, and 762+/-5 nm) for the absolute intensity measurement of the TLE emission. One of six photometers equips a wide-band filter (600-900 nm) to detect light-ning occurring within 86.8 deg. FOV. These output signals will be recorded with the sampling frequency of 20 kHz with a 12-bit resolution. One of two electromagnetic instruments is a VLF receiver (VLFR), which measures electromagnetic waves in the frequency range of 1-40 kHz with 16-bit resolution. Another instrument is VHF interferometer (VITF), which measures VHF pulses generated lightning discharge in the frequency range of 70-100 MHz. JEM-GIMS will be launched in 2011. We have passed the critical design review (CDR) on January and February and have started the fabrication of the proto-flight model. We will present the devel-opment status of the JEM-GLISM optical instruments and discuss the scientific outputs derived from this mission more in detail.

Improving Air Quality Forecasts with AURA Observations

NASA Technical Reports Server (NTRS)

Newchurch, M. J.; Biazer, A.; Khan, M.; Koshak, W. J.; Nair, U.; Fuller, K.; Wang, L.; Parker, Y.; Williams, R.; Liu, X.

2008-01-01

Past studies have identified model initial and boundary conditions as sources of reducible errors in air-quality simulations. In particular, improving the initial condition improves the accuracy of short-term forecasts as it allows for the impact of local emissions to be realized by the model and improving boundary conditions improves long range transport through the model domain, especially in recirculating anticyclones. During the August 2006 period, we use AURA/OMI ozone measurements along with MODIS and CALIPSO aerosol observations to improve the initial and boundary conditions of ozone and Particulate Matter. Assessment of the model by comparison of the control run and satellite assimilation run to the IONS06 network of ozonesonde observations, which comprise the densest ozone sounding campaign ever conducted in North America, to AURA/TES ozone profile measurements, and to the EPA ground network of ozone and PM measurements will show significant improvement in the CMAQ calculations that use AURA initial and boundary conditions. Further analyses of lightning occurrences from ground and satellite observations and AURA/OMI NO2 column abundances will identify the lightning NOx signal evident in OMI measurements and suggest pathways for incorporating the lightning and NO2 data into the CMAQ simulations.

Adolescents' perceived risk and personal experience with natural disasters: an evaluation of cognitive heuristics.

PubMed

Greening, L; Dollinger, S J; Pitz, G

1996-02-01

Elevated risk judgments for negative life events have been linked to personal experience with events. We tested the hypothesis that cognitive heuristics are the underlying cognitive mechanism for this relation. The availability (i.e., memory for incidents) and simulation (i.e., imagery) heuristics were evaluated as possible mediators for the relation between personal experience and risk estimates for fatal weather events. Adolescents who had experienced weather disasters estimated their personal risk for weather events. Support was obtained for the simulation heuristic (imagery) as a mediator for the relation. Availability for lightning disaster experience was also found to be a mediator for the relation between personal lightning disaster experience and risk estimate for future events. The implications for risk perception research are discussed.

Development of a positive corona from a long grounded wire in a growing thunderstorm field

NASA Astrophysics Data System (ADS)

Mokrov, M. S.; Raizer, Yu P.; Bazelyan, E. M.

2013-11-01

The properties of a non-stationary corona initiated from a long grounded wire suspended horizontally above the ground and coronating in a slowly varying thundercloud electric field are studied. A two-dimensional (2D) model of the corona is developed. On the basis of this model, characteristics of the corona produced by a lightning protection wire are calculated under thunderstorm conditions. The corona characteristics are also found by using approximate analytical and quasi-one-dimensional numerical models. The results of these models agree reasonably well with those obtained from the 2D simulation. This allows one to estimate the corona parameters without recourse to the cumbersome simulation. This work was performed with a view to study the efficiency of lightning protection wires later on.

KSC-00pp0892

NASA Image and Video Library

2000-06-19

KENNEDY SPACE CENTER, FLA. -- At KSC's Shuttle Landing Facility, a specially equipped Cessna Citation aircraft flies over the runway to calibrate the Cesna's field mills with field mills on the ground (on the tripod at left) and on the car parked nearby (at center). Field mills measure electric fields. The aircraft is also equipped with cloud physics probes that measure the size, shape and number of ice and water particles in clouds. The plane is being flown into anvil clouds in the KSC area as part of a study to review and possibly modify lightning launch commit criteria. The weather study could lead to improved lightning avoidance rules and fewer launch scrubs for the Space Shuttle and other launch vehicles on the Eastern and Western ranges.

KSC00pp0892

NASA Image and Video Library

2000-06-19

KENNEDY SPACE CENTER, FLA. -- At KSC's Shuttle Landing Facility, a specially equipped Cessna Citation aircraft flies over the runway to calibrate the Cesna's field mills with field mills on the ground (on the tripod at left) and on the car parked nearby (at center). Field mills measure electric fields. The aircraft is also equipped with cloud physics probes that measure the size, shape and number of ice and water particles in clouds. The plane is being flown into anvil clouds in the KSC area as part of a study to review and possibly modify lightning launch commit criteria. The weather study could lead to improved lightning avoidance rules and fewer launch scrubs for the Space Shuttle and other launch vehicles on the Eastern and Western ranges.

3D modeling of lightning-induced electromagnetic pulses on Venus, Jupiter and Saturn

NASA Astrophysics Data System (ADS)

Pérez-Invernón, Francisco J.; Luque, Alejandro; Gordillo-Vázquez, Francisco J.

2017-04-01

Atmospheric electricity is a common phenomenon in some planets of The Solar System. We know that atmospheric discharges exist on Earth and gaseous planets; however, some characteristics of lightning on Saturn and Jupiter as well as their relevance on the effects of lightning in the atmospheres of these planets are still unknown. In the case of Venus, there exist some radio evidences of lightning, but the lack of optical observations suggests exploring indirect methods of detection, such as searching for lightning-induced transient optical emissions from the upper atmosphere. The Akatsuki probe, currently orbiting Venus, is equipped with a camera whose temporal resolution is high enough to detect optical emissions from lightning discharges and to measure nightglow enhancements. In this work, we extend previous models [1,2] to investigate the chemical impact and transient optical emissions produced by possible lightning-emitted electromagnetic pulses (EMP) in Venus, Saturn and Jupiter. Using a 3D FDTD ("Finite Differences Time Domain") model we solve the Maxwell equations coupled with the Langevin equation for electrons [3] and with a kinetic scheme, different for each planetary atmosphere. This method is useful to investigate the temporal and spatial impact of lightning-induced electromagnetic fields in the atmosphere of each planet for different lightning characteristics (e.g. energy released, orientation). This 3D FDTD model allows us to include the saturnian and jovian background magnetic field inclination and magnitude at different latitudes, and to determine the effects of different lightning channel inclinations. Results provide useful information to interpret lightning observations on giant gaseous planets and in the search for indirect optical signals from atmospheric discharge on Venus such as fast nightglow transient enhancements related to lightning as seen on Earth. Furthermore, we underline the observation of electrical discharges characteristics as a powerful tool to obtain information about planetary atmospheres, such as density profiles of electrons or other components. Our model may also be useful to extend some studies about the chemical impact of EMP pulses in the terrestrial atmosphere [4]. References [1] Luque, A., D. Dubrovin, F. J. Gordillo-Vázquez, U. Ebert, F. C. Parra-Rojas, Y. Yair, and C. Price (2014), Coupling between atmospheric layers in gaseous giant planets due to lightning-generated electromagnetic pulses, J. Geophys. Res. (Space Phys), 119, 8705, doi: 10.1002/2014JA020457. [2] Pérez-Invernón, F. J., A. Luque, and F. J. Gordillo-Vázquez (2016), Mesospheric optical signatures of possible lightning on Venus, J. Geophys. Res. (Space Phys), 121, 7026, doi: 10.1029/2016JA022886. [3] Lee, J. H., and D. K. Kalluri (1999), Three-dimensional FDTD simulation of electromagnetic wave transformation in a dynamic inhomogeneous magnetized plasma, IEEE Transactions on Antennas and Propagation, 47, 1146, doi:10.1109/8.785745. [4] Marshall, R. A., U. S. Inan, and V. S. Glukhov (2010), Elves and associated electron density changes due to cloud-to-ground and in-cloud lightning discharges, J. Geophys. Res. (Space Phys), 115, A00E17, doi:10.1029/2009JA014469.

ALDF Data Retrieval Algorithms for Validating the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS)

NASA Technical Reports Server (NTRS)

Koshak, W. J.; Blakeslee, R. J.; Bailey, J. C.

1997-01-01

A linear algebraic solution is provided for the problem of retrieving the location and time of occurrence of lightning ground strikes from in Advanced Lightning Direction Finder (ALDF) network. The ALDF network measures field strength, magnetic bearing, and arrival time of lightning radio emissions and solutions for the plane (i.e.. no Earth curvature) are provided that implement all of these measurements. The accuracy of the retrieval method is tested using computer-simulated data sets and the relative influence of bearing and arrival time data on the outcome of the final solution is formally demonstrated. The algorithm is sufficiently accurate to validate NASA's Optical Transient Detector (OTD) and Lightning Imaging System (LIS). We also introduce a quadratic planar solution that is useful when only three arrival time measurements are available. The algebra of the quadratic root results are examined in detail to clarify what portions of the analysis region lead to fundamental ambiguities in source location. Complex root results are shown to be associated with the presence of measurement errors when the lightning source lies near an outer sensor baseline of the ALDF network. For arbitrary noncollinear network geometries and in the absence of measurement errors, it is shown that the two quadratic roots are equivalent (no source location ambiguity) on the outer sensor baselines. The accuracy of the quadratic planar method is tested with computer-generated data sets and the results are generally better than those obtained from the three station linear planar method when bearing errors are about 2 degrees.

Assimilation of total lightning data using the three-dimensional variational method at convection-allowing resolution

NASA Astrophysics Data System (ADS)

Zhang, Rong; Zhang, Yijun; Xu, Liangtao; Zheng, Dong; Yao, Wen

2017-08-01

A large number of observational analyses have shown that lightning data can be used to indicate areas of deep convection. It is important to assimilate observed lightning data into numerical models, so that more small-scale information can be incorporated to improve the quality of the initial condition and the subsequent forecasts. In this study, the empirical relationship between flash rate, water vapor mixing ratio, and graupel mixing ratio was used to adjust the model relative humidity, which was then assimilated by using the three-dimensional variational data assimilation system of the Weather Research and Forecasting model in cycling mode at 10-min intervals. To find the appropriate assimilation time-window length that yielded significant improvement in both the initial conditions and subsequent forecasts, four experiments with different assimilation time-window lengths were conducted for a squall line case that occurred on 10 July 2007 in North China. It was found that 60 min was the appropriate assimilation time-window length for this case, and longer assimilation window length was unnecessary since no further improvement was present. Forecasts of 1-h accumulated precipitation during the assimilation period and the subsequent 3-h accumulated precipitation were significantly improved compared with the control experiment without lightning data assimilation. The simulated reflectivity was optimal after 30 min of the forecast, it remained optimal during the following 42 min, and the positive effect from lightning data assimilation began to diminish after 72 min of the forecast. Overall, the improvement from lightning data assimilation can be maintained for about 3 h.

Cable coupling lightning transient qualification

NASA Technical Reports Server (NTRS)

Cook, M.

1989-01-01

Simulated lightning strike testing of instrumentation cabling on the redesigned solid rocket motor was performed. Testing consisted of subjecting the lightning evaluation test article to simulated lightning strikes and evaluating the effects of instrumentation cable transients on cables within the system tunnel. The maximum short-circuit current induced onto a United Space Boosters, Inc., operational flight cable within the systems tunnel was 92 A, and the maximum induced open-circuit voltage was 316 V. These levels were extrapolated to the worst-case (200 kA) condition of NASA specification NSTS 07636 and were also scaled to full-scale redesigned solid rocket motor dimensions. Testing showed that voltage coupling to cables within the systems tunnel can be reduced 40 to 90 dB and that current coupling to cables within the systems tunnel can be reduced 30 to 70 dB with the use of braided metallic sock shields around cables that are external to the systems tunnel. Testing also showed that current and voltage levels induced onto cables within the systems tunnel are partially dependant on the cables' relative locations within the systems tunnel. Results of current injections to the systems tunnel indicate that the dominant coupling mode on cables within the systems tunnel is not from instrumentation cables but from coupling through the systems tunnel cover seam apertures. It is recommended that methods of improving the electrical bonding between individual sections of the systems tunnel covers be evaluated. Further testing to better characterize redesigned solid rocket motor cable coupling effects as an aid in developing methods to reduce coupling levels, particularly with respect to cable placement within the systems tunnel, is also recommended.

Production of low molecular weight hydrocarbons by volcanic eruptions on early Mars.

PubMed

Segura, Antígona; Navarro-González, Rafael

2005-10-01

Methane and other larger hydrocarbons have been proposed as possible greenhouse gases on early Mars. In this work we explore if volcanic processes may have been a source for such molecules based on theoretical and experimental considerations. Geologic evidence and numerical simulations indicate that explosive volcanism was widely distributed throughout Mars. Volcanic lightning is typically produced in such explosive volcanism. Therefore this geologic setting was studied to determine if lightning could be a source for hydrocarbons in volcanic plumes. Volcanic lightning was simulated by focusing a high-energy infrared laser beam inside of a Pyrex reactor that contained the proposed volcanic gas mixture composed of 64% CH(4), 24% H(2), 10% H(2)O and 2% N(2), according to an accretion model and the nitrogen content measured in Martian meteorites. The analysis of products was performed by gas chromatography coupled to infrared and mass spectroscopy. Eleven hydrocarbons were identified among the products, of which acetylene (C(2)H(2)) was the most abundant. A thermochemical model was used to determine which hydrocarbons could arise only from volcanic heat. In this case, acetylene and ethylene are formed at magmatic temperatures. Our results indicate that explosive volcanism may have injected into the atmosphere of early Mars approximately 6 x 10(12) g yr(-1) of acetylene, and approximately 2 x 10(12) g yr(-1) of 1,3-butadiyne, both produced by volcanic lightning, approximately 5 x 10(11) g yr(-1) of ethylene produced by volcanic heat, and 10(13) g yr(-1) of methane.

Modeling Lightning Impact Thermo-Mechanical Damage on Composite Materials

NASA Astrophysics Data System (ADS)

Muñoz, Raúl; Delgado, Sofía; González, Carlos; López-Romano, Bernardo; Wang, De-Yi; LLorca, Javier

2014-02-01

Carbon fiber-reinforced polymers, used in primary structures for aircraft due to an excellent strength-to-weight ratio when compared with conventional aluminium alloy counterparts, may nowadays be considered as mature structural materials. Their use has been extended in recent decades, with several aircraft manufacturers delivering fuselages entirely manufactured with carbon composites and using advanced processing technologies. However, one of the main drawbacks of using such composites entails their poor electrical conductivity when compared with aluminium alloy competitors that leads to lightning strikes being considered a significant threat during the service life of the aircraft. Traditionally, this problem was overcome with the use of a protective copper/bronze mesh that added additional weight and reduced the effectiveness of use of the material. Moreover, this traditional sizing method is based on vast experimental campaigns carried out by subjecting composite panels to simulated lightning strike events. While this method has proven its validity, and is necessary for certification of the structure, it may be optimized with the aid provided by physically based numerical models. This paper presents a model based on the finite element method that includes the sources of damage observed in a lightning strike, such as thermal damage caused by Joule overheating and electromagnetic/acoustic pressures induced by the arc around the attachment points. The results of the model are compared with lightning strike experiments carried out in a carbon woven composite.

Cost of Lightning Strike Related Outages of Visual Navigational Aids at Airports in the United States

NASA Astrophysics Data System (ADS)

Rakas, J.; Nikolic, M.; Bauranov, A.

2017-12-01

Lightning storms are a serious hazard that can cause damage to vital human infrastructure. In aviation, lightning strikes cause outages to air traffic control equipment and facilities that result in major disruptions in the network, causing delays and financial costs measured in the millions of dollars. Failure of critical systems, such as Visual Navigational Aids (Visual NAVAIDS), are particularly dangerous since NAVAIDS are an essential part of landing procedures. Precision instrument approach, an operation utilized during the poor visibility conditions, utilizes several of these systems, and their failure leads to holding patterns and ultimately diversions to other airports. These disruptions lead to both ground and airborne delay. Accurate prediction of these outages and their costs is a key prerequisite for successful investment planning. The air traffic management and control sector need accurate information to successfully plan maintenance and develop a more robust system under the threat of increasing lightning rates. To analyze the issue, we couple the Remote Monitoring and Logging System (RMLS) database and the Aviation System Performance Metrics (ASPM) databases to identify lightning-induced outages, and connect them with weather conditions, demand and landing runway to calculate the total delays induced by the outages, as well as the number of cancellations and diversions. The costs are then determined by calculating direct costs to aircraft operators and costs of passengers' time for delays, cancellations and diversions. The results indicate that 1) not all NAVAIDS are created equal, and 2) outside conditions matter. The cost of an outage depends on the importance of the failed system and the conditions that prevailed before, during and after the failure. The outage that occurs during high demand and poor weather conditions is more likely to result in more delays and higher costs.

A method for estimating the probability of lightning causing a methane ignition in an underground mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sacks, H.K.; Novak, T.

2008-03-15

During the past decade, several methane/air explosions in abandoned or sealed areas of underground coal mines have been attributed to lightning. Previously published work by the authors showed, through computer simulations, that currents from lightning could propagate down steel-cased boreholes and ignite explosive methane/air mixtures. The presented work expands on the model and describes a methodology based on IEEE Standard 1410-2004 to estimate the probability of an ignition. The methodology provides a means to better estimate the likelihood that an ignition could occur underground and, more importantly, allows the calculation of what-if scenarios to investigate the effectiveness of engineering controlsmore » to reduce the hazard. The computer software used for calculating fields and potentials is also verified by comparing computed results with an independently developed theoretical model of electromagnetic field propagation through a conductive medium.« less

Electron density increases due to Lightning activity as deduced from LWPC code and VLF signal perturbations.

NASA Astrophysics Data System (ADS)

Samir, Nait Amor; Bouderba, Yasmina

VLF signal perturbations in association with thunderstorm activity appear as changes in the signal amplitude and phase. Several papers reported on the characteristics of thus perturbations and their connection to the lightning strokes amplitude and polarity. In this contribution, we quantified the electrons density increases due to lightning activity by the use of the LWPC code and VLF signal perturbations parameters. The method is similar to what people did in studying the solar eruptions effect. the results showed that the reference height (h') decreased to lower altitudes (between 70 and 80 km). From the LWPC code results the maximum of the electron density was then deduced. Therefore, a numerical simulation of the atmospheric species times dependences was performed to study the recovery times of the electrons density at different heights. The results showed that the recovery time last for several minutes and explain the observation of long recovery Early signal perturbations.

Data and results of a laboratory investigation of microprocessor upset caused by simulated lightning-induced analog transients

NASA Technical Reports Server (NTRS)

Belcastro, C. M.

1984-01-01

Advanced composite aircraft designs include fault-tolerant computer-based digital control systems with thigh reliability requirements for adverse as well as optimum operating environments. Since aircraft penetrate intense electromagnetic fields during thunderstorms, onboard computer systems maya be subjected to field-induced transient voltages and currents resulting in functional error modes which are collectively referred to as digital system upset. A methodology was developed for assessing the upset susceptibility of a computer system onboard an aircraft flying through a lightning environment. Upset error modes in a general-purpose microprocessor were studied via tests which involved the random input of analog transients which model lightning-induced signals onto interface lines of an 8080-based microcomputer from which upset error data were recorded. The application of Markov modeling to upset susceptibility estimation is discussed and a stochastic model development.

Lightning characterization through acoustic and electromagnetic measurements recorded during the HyMeX SOP1 and simulation of the acoustic nonlinear propagation in realistic thunderstorm meteorological conditions

NASA Astrophysics Data System (ADS)

Gallin, L.; Coulouvrat, F.; Farges, T.; Marchiano, R.; Defer, E.; Rison, W.; Schulz, W.; Nuret, M.

2013-12-01

The goal is to study the transformation of the thunder (amplitude, spectrum) during its travel from the lightning channel towards a detector (microphone, microbarometer), considering propagation distances of less than 50 km and complex local meteorological properties. Inside the European HyMeX project, the SOP1 campaign (2012) took place from September 2012 to November 2012 in South of France. An acoustic station (center: 4.39° E, 44.08° N) composed of a microphone array placed inside a microbarometer array was installed by CEA near city of Uzès. It was located in the center of an LMA network coming with two slow antennas. This network was deployed in France for the first time by the New Mexico Tech and LERMA laboratory. The detections from the European lightning location system EUCLID complete this dataset. During the SOP1 period several storms passed over the station. The post-processings of the records point out days with interesting thunderstorms. Especially during the 26th of October 2012 in the evening (around 8 pm) a thunderstorm passed just over the acoustic station. Not too many lightning strokes are detected by EUCLID, the corresponding flashes are then well characterized by the LMA network. Slow antennas present good electric field measurements. The acoustic records have excellent quality. We present for some selected flashes a comparative study of the different measurements (LMA, slow antenna, EUCLID, microphones, microbarometers): focusing on amplitude and spectrum of the thunder waveforms, and on propagation effects due to the meteorological conditions. To quantify the impact of these meteorological conditions on the propagating thunder (from the lightning sources to the acoustic array), a code named Flhoward is used [Dagrau et al., J. Acoust. Soc. Am., 130, 20-32, 2011][Coulouvrat, Wave Motion, 49, 50--63, 2012]. It is designed to simulate the nonlinear propagation of acoustic shock waves through a realistic atmosphere model (including temperature gradients, rigid ground, and wind flows). The meteorological conditions are extracted from the data calculated by Météo-France weather forecast model AROME-WMED for the chosen days. Some cases where numerical simulation helps to understand the observations are presented.

Development of a pin-post insulator with built-in metal oxide varistors for distribution lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujiwara, N.; Yoneyama, T.; Hamada, Y.

1996-04-01

A 6.6 kV pin-post insulator, incorporating ZnO varistors, has been developed in order to reduce line faults caused by direct lighting strikes, thereby reducing and simplifying maintenance work on distribution systems. The developed insulators are interchangeable with conventional pin insulators and can withstand internal fault currents twice upon their failures. The simulated results regarding the response of the developed insulators to direct lightning strikes on an overhead ground wire agreed well with the experimental results. Simulation studies also revealed that installing the developed insulators on every two poles reduces the line-fault rate of present distribution lines in case of directmore » lightning strikes by 33%, while installing them on every pole reduces the rate by 97.5% or about 1/40 of the original value.« less

Structural and erosive Effects of Lightning on Sandstone: An Experimental Investigation

NASA Astrophysics Data System (ADS)

Haddad, Houssam; Ebert, Matthias; Kenkmann, Thomas; Thoma, Klaus; Nau, Siegfried; Schäfer, Frank

2016-04-01

Recent prognoses predict an average temperature increase of the world's climate of about 1.5 to 2 °C until the end of 21st century. This change leads not only to a rise of the sea level but also to an increase of thunderstorms and therefore to a ~25 percent increase of cloud-to-ground lightning events (Romps et al., 2014). It is known that (i) lightning strikes are able to fragment surface rocks, which probably influences the erosion rates at exposed mountain areas (Knight and Grab, 2014), and (ii) the efficiency of the process increases due to the predicted climate change. However, our knowledge about the electro-mechanical destruction of rocks caused by high energetic lightning is incomplete. In this study, laboratory experiments of lightning strikes were performed in order to understand the fragmentation of rocks and changes to landforms by lightning. The artificial lightning with known electric current was simulated by a high-current generator in the laboratories of the Fraunhofer Ernst-Mach Institute for High-Speed Dynamics (Freiburg, Germany). Different currents were transferred over a distance of ~2mm onto water-saturated sandstones by using a copper cathode (3 experiments; U, I, E, Δt: 6 kV, 200 kA, 0.1 MJ, 0.7 ms; 9 kV, 300 kA, 0.19 MJ, 0.9 ms; 12 kV, 400 kA, 0.35 MJ, 0.5 ms). The damaged sandstones were investigated by means of optical and electron-optical methods as well as by X-ray computed tomography to determine the modes and dimensions of melting and fragmentation. Digital elevation models of craters formed by ejection were obtained by white-light interferometry. The lightning experiments produced small craters (~1 cm in diameter, ~0.5 cm depth) which surfaces and sub-surfaces consist of silicate melts (molten quartz and phyllosilicates). The silicate melts reach several hundred micrometers into the sub-surface and resemble the appearance of natural fulgurites. Melting of quartz indicate temperatures of at least 1650 °C. In addition, the occurrence of macroscopic and microscopic fractures was observed. Large fractures, which are several millimeters in length, propagate radial-symmetrically from the impact point into the sandstone. The extent and depth of the produced lighting craters, the amount of melt and the amount of fractures increases with increasing energy of the artificial lightning strike. The experiments show that the largest fraction of the input energy is invested in heating and melt formation, and secondary in fragmentation. The melt and crater volumes are considered representative for the erosive power of this physical process. Based on our investigations, the global lightning strikes' density and the assumption that around 1-10 MJ of natural lightning strikes are delivered to the strike point, a maximum erosion rate of lightning of about ~1.8 μm/yr could be calculated. This result indicates that cloud-to-ground lightning play a non-negligible role in the global erosion system. References: Knight J. & Grab S.W. (2014) Lightning as a geomorphic agent on mountain summits: evidence from southern Africa. Geomorphology 204, 61-70. Romps D.M., Seeley J.T., Vollaro D., & Molinari J. (2014) Projected increase in lightning strikes in the United States due to global warming. Science 346, 851-854.

Improvements to a High Spectral Resolution, Radiation-Hydrodynamics Model of a Lightning Return Stroke and Comparisons with Measured Spectra and Inferred Plasma Properties

NASA Astrophysics Data System (ADS)

Edwards, J. D.; Dreike, P.; Smith, M. W.; Clemenson, M. D.; Zollweg, J. D.

2015-12-01

We describe developments to a 1-D cylindrical, radiation-hydrodynamics model of a lightning return stroke that simulates lighting spectra with 1 Angstrom resolution in photon wavelength. In previous calculations we assumed standard density air in the return stroke channel and the resulting optical spectrum was that of an optically thick emitter, unlike measured spectra that are optically thin. In this work, we improve our model by initializing our simulation assuming that the leader-heated channel is pre-expanded to a density of 0.01-0.05 ambient and near pressure equilibrium with the surrounding ambient air and by implementing a time-dependent, external heat source to incorporate the effects of continuing current. By doing so, our simulated spectra, illustrated in the attached figure, show strong spectral emission characteristics at wavelengths similar to spectra measured by Orville (1968). In this poster, we describe our model and compare our simulated results with spectra measured by Orville (1968) and Smith (2015). We also use spectroscopic methods to compute physical properties of the plasma channel, e.g. temperature, from Smith's measurements and compare these with our simulated results.

49 CFR 195.575 - Which facilities must I electrically isolate and what inspections, tests, and safeguards are...

Code of Federal Regulations, 2013 CFR

2013-10-01

... reasonable to foresee fault currents or an unusual risk of lightning, you must protect the pipeline against... metallic structures, unless you electrically interconnect and cathodically protect the pipeline and the... isolation of a portion of a pipeline is necessary to facilitate the application of corrosion control. (c...

49 CFR 195.575 - Which facilities must I electrically isolate and what inspections, tests, and safeguards are...

Code of Federal Regulations, 2014 CFR

2014-10-01

... reasonable to foresee fault currents or an unusual risk of lightning, you must protect the pipeline against... metallic structures, unless you electrically interconnect and cathodically protect the pipeline and the... isolation of a portion of a pipeline is necessary to facilitate the application of corrosion control. (c...

49 CFR 195.575 - Which facilities must I electrically isolate and what inspections, tests, and safeguards are...

Code of Federal Regulations, 2012 CFR

2012-10-01

... reasonable to foresee fault currents or an unusual risk of lightning, you must protect the pipeline against... metallic structures, unless you electrically interconnect and cathodically protect the pipeline and the... isolation of a portion of a pipeline is necessary to facilitate the application of corrosion control. (c...

Lightning and anthropogenic NOx sources over the U.S. and the western North Atlantic Ocean: Impact on tropospheric O3 from space-borne observations

NASA Astrophysics Data System (ADS)

Choi, Y.; Eldering, A.; Osterman, G.; Wang, Y.; Cunnold, D.; Yang, Q.; Bucsela, E.; Pickering, K.

2008-12-01

We use the Regional chEmical trAnsport Model (REAM) to analyze the contributions of lightning and anthropogenic NOx on ozone concentrations over the U.S. and the western North Atlantic Ocean from June to August 2005. Tropospheric NO2 columns from OMI, tropospheric O3 columns derived from OMI and MLS measurements, and vertical O3 profiles from TES over the region are used in the analysis. With a 50% reduction in the industrial and electrical power generation NOx emissions in the 23 eastern states over the U.S. from 1999 EPA NEI and a parameterization of lightning-produced NOx based on concurrent NLDN, CAPE, and cloud mass flux data, REAM generally captures the spatial distribution of lightning flash rates and OMI NO2 and OMI-MLS O3 column enhancements with high correlation coefficients (0.6-0.9). The model results show that over the U.S., the contribution of surface NOx emissions to summertime tropospheric O3 declines from 47% to 41% due to the reduced emissions. The contribution of surface NOx emissions becomes similar to that of stratospheric transport over the U.S., with the additional being the dramatic reduction in the relative impact of fossil-fuel NOx emissions over continental outflow regions. In the convective outflow regions over the Gulf of Mexico and the western North Atlantic, the contribution of lightning NOx production on tropospheric O3 in the summer is larger than that of anthropogenic NOx emissions with mean differences of 5% to 25%. The impact of NOx produced by lightning is becoming larger as fossil-fuel combustion NOx emissions decrease. After the onset of the North American monsoon, lightning-derived upper tropospheric O3 enhancements in July and August are shown over the convective outflow regions from REAM simulated and TES measured O3 vertical profiles. This result suggests that TES measurements have a potential to constrain lightning-derived tropospheric O3 enhancements, which may play a critical role in controlling climate.

Nature and Intensity of the 22-23 April 2015 Eruptions of Volcán Calbuco, Chile, from Satellite, Lightning, and Field Observations

NASA Astrophysics Data System (ADS)

Van Eaton, A. R.; Amigo, A.; Bertin, D.; Mastin, L. G.; Giacosa, R.; Behnke, S. A.

2015-12-01

On 22 April 2015, Calbuco Volcano in southern Chile erupted for the first time in 43 years. The two primary phases of eruption, separated by a few hours, produced pyroclastic density currents, lahars, and spectacular vertical eruption columns that rose into the stratosphere. Clear weather conditions allowed the populated areas of Puerto Montt and Puerto Varas full view of the lightning-rich eruption, which was rapidly shared through social media. A wealth of remote-sensing data was also publically available in near real-time. We used this information to assess the eruption behavior by combining satellite-based umbrella growth rates, and the location and frequency of volcanic lightning. Umbrella expansion rates from GOES-13 satellite retrievals correspond to eruption rates of about 4x106 kg s-1 for the first eruptive phase and 6x106 kg s-1 for the second phase, following the approach of Pouget et al. (2013, JVGR, 258, 100-112). The location and timing of lightning flashes were obtained from the World Wide Lightning Location Network (WWLLN) Global Volcanic Lightning Monitor, which is updated approximately every minute (Ewert et al., 2010, Fall AGU Abstract AE31A-04). Interestingly, the onset of detected flashes was delayed by ~30 min after the start of each eruptive phase. Lighting provided a useful proxy for the waxing or waning intensity of the eruption, and helped identify the end of significant ash emissions. Using the 1-D volcanic plume model Plumeria, we have also simulated the vertical distribution of ash and ice in the plumes to examine potential causes of the extraordinary amount of volcanic lightning (1,094 flashes detected). Our analysis provides information on eruption timing, duration, and mass flow rate, which are necessary for ash dispersal modeling within hours of eruption. Results are also consistent with the field-based measurements of total erupted volume. We suggest that the combination of satellite-detected umbrella expansion rates with lightning data may provide a useful approach to constrain near real-time inputs for ash dispersal models and hazard warnings.

NO{sub x} from lightning 1. Global distribution based on lightning physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Price, C.; Penner, J.; Prather, M.

1997-03-01

This paper begins a study on the role of lightning in maintaining the global distribution of nitrogen oxides (NO{sub x}) in the troposphere. It presents the first global and seasonal distributions of lightning-produced NO{sub x} (LNO{sub x}) based on the observed distribution of electrical storms and the physical properties of lightning strokes. We derive a global rate for cloud-to-ground (CG) flashes of 20{endash}30 flashes/s with a mean energy per flash of 6.7{times}10{sup 9}J. Intracloud (IC) flashes are more frequent, 50{endash}70 flashes/s but have 10{percent} of the energy of CG strokes and, consequently, produce significantly less NO{sub x}. It appears tomore » us that the majority of previous studies have mistakenly assumed that all lightning flashes produce the same amount of NO{sub x}, thus overestimating the NO{sub x} production by a factor of 3. On the other hand, we feel these same studies have underestimated the energy released in CG flashes, resulting in two negating assumptions. For CG energies we adopt a production rate of 10{times}10{sup 16} molecules NO/J based on the current literature. Using a method to simulate global lightning frequencies from satellite-observed cloud data, we have calculated the LNO{sub x} on various spatial (regional, zonal, meridional, and global) and temporal scales (daily, monthly, seasonal, and interannual). Regionally, the production of LNO{sub x} is concentrated over tropical continental regions, predominantly in the summer hemisphere. The annual mean production rate is calculated to be 12.2 Tg N/yr, and we believe it extremely unlikely that this number is less than 5 or more than 20 Tg N/yr. Although most of LNO{sub x} is produced in the lowest 5 km by CG lightning, convective mixing in the thunderstorms is likely to deposit large amounts of NO{sub x} in the upper troposphere where it is important in ozone production. (Abstract Truncated)« less

KSC00pp0889

NASA Image and Video Library

2000-06-19

At KSC’s Shuttle Landing Facility, a specially equipped Cessna Citation aircraft flies over the runway to calibrate the Cessna’s field mills with field mills on the ground (on the tripod at left) and on the car parked nearby (at right). Field mills measure electric fields. The aircraft is also equipped with cloud physics probes that measure the size, shape and number of ice and water particles in clouds. The plane is being flown into anvil clouds in the KSC area as part of a study to review and possibly modify lightning launch commit criteria. The weather study could lead to improved lightning avoidance rules and fewer launch scrubs for the Space Shuttle and other launch vehicles on the Eastern and Western ranges.; More information about this study can be found in Release No. 56-00

KSC-00pp0891

NASA Image and Video Library

2000-06-19

At KSC’s Shuttle Landing Facility, a specially equipped Cessna Citation aircraft approaches the runway to calibrate the Cessna’s field mills with field mills on the ground (on the tripod at left) and on the car parked nearby (at right). Field mills measure electric fields. The aircraft is also equipped with cloud physics probes that measure the size, shape and number of ice and water particles in clouds. The plane is being flown into anvil clouds in the KSC area as part of a study to review and possibly modify lightning launch commit criteria. The weather study could lead to improved lightning avoidance rules and fewer launch scrubs for the Space Shuttle and other launch vehicles on the Eastern and Western ranges.; More information on this study can be found in Release No. 56-00

KSC00pp0891

NASA Image and Video Library

2000-06-19

At KSC’s Shuttle Landing Facility, a specially equipped Cessna Citation aircraft approaches the runway to calibrate the Cessna’s field mills with field mills on the ground (on the tripod at left) and on the car parked nearby (at right). Field mills measure electric fields. The aircraft is also equipped with cloud physics probes that measure the size, shape and number of ice and water particles in clouds. The plane is being flown into anvil clouds in the KSC area as part of a study to review and possibly modify lightning launch commit criteria. The weather study could lead to improved lightning avoidance rules and fewer launch scrubs for the Space Shuttle and other launch vehicles on the Eastern and Western ranges.; More information on this study can be found in Release No. 56-00

KSC-00pp0889

NASA Image and Video Library

2000-06-19

At KSC’s Shuttle Landing Facility, a specially equipped Cessna Citation aircraft flies over the runway to calibrate the Cessna’s field mills with field mills on the ground (on the tripod at left) and on the car parked nearby (at right). Field mills measure electric fields. The aircraft is also equipped with cloud physics probes that measure the size, shape and number of ice and water particles in clouds. The plane is being flown into anvil clouds in the KSC area as part of a study to review and possibly modify lightning launch commit criteria. The weather study could lead to improved lightning avoidance rules and fewer launch scrubs for the Space Shuttle and other launch vehicles on the Eastern and Western ranges.; More information about this study can be found in Release No. 56-00

Applied Meteorology Unit Quarterly Report. First Quarter FY-13

NASA Technical Reports Server (NTRS)

2013-01-01

The AMU team worked on five tasks for their customers: (1) Ms. Crawford continued work on the objective lightning forecast task for airports in east-central Florida. (2) Ms. Shafer continued work on the task for Vandenberg Air Force Base to create an automated tool that will help forecasters relate pressure gradients to peak wind values. (3) Dr. Huddleston began work to develop a lightning timing forecast tool for the Kennedy Space Center/Cape Canaveral Air Force Station area. (3) Dr. Bauman began work on a severe weather forecast tool focused on east-central Florida. (4) Dr. Watson completed testing high-resolution model configurations for Wallops Flight Facility and the Eastern Range, and wrote the final report containing the AMU's recommendations for model configurations at both ranges.

FDTD Modeling of LEMP Propagation in the Earth-Ionosphere Waveguide With Emphasis on Realistic Representation of Lightning Source

NASA Astrophysics Data System (ADS)

Tran, Thang H.; Baba, Yoshihiro; Somu, Vijaya B.; Rakov, Vladimir A.

2017-12-01

The finite difference time domain (FDTD) method in the 2-D cylindrical coordinate system was used to compute the nearly full-frequency-bandwidth vertical electric field and azimuthal magnetic field waveforms produced on the ground surface by lightning return strokes. The lightning source was represented by the modified transmission-line model with linear current decay with height, which was implemented in the FDTD computations as an appropriate vertical phased-current-source array. The conductivity of atmosphere was assumed to increase exponentially with height, with different conductivity profiles being used for daytime and nighttime conditions. The fields were computed at distances ranging from 50 to 500 km. Sky waves (reflections from the ionosphere) were identified in computed waveforms and used for estimation of apparent ionospheric reflection heights. It was found that our model reproduces reasonably well the daytime electric field waveforms measured at different distances and simulated (using a more sophisticated propagation model) by Qin et al. (2017). Sensitivity of model predictions to changes in the parameters of atmospheric conductivity profile, as well as influences of the lightning source characteristics (current waveshape parameters, return-stroke speed, and channel length) and ground conductivity were examined.

Predicting the characteristics of thunder on Titan: A framework to assess the detectability of lightning by acoustic sensing

NASA Astrophysics Data System (ADS)

Petculescu, Andi; Kruse, Roland

2014-10-01

The search for lightning is an important item on the agenda for the future exploration of Titan. Thunder, as a direct lightning signature, can be used, together with electromagnetic signals, to corroborate and quantify lightning. Using Cassini-Huygens data and model predictions, the main characteristics of thunder produced by a potential 20 km cloud-to-ground tortuous discharge are obtained and discussed. The acoustic power released right after the discharge decreases with increasing altitude, owing to the ambient pressure and temperature gradients. Ray tracing is used to propagate sound waves to the far field. Simulated thunder waveforms are characterized by fairly long codas—on the order of tens of seconds—arising from the small acoustic absorption (˜10-4dB/km). In the low-loss environment, the principal thunder arrival will likely have a large signal-to-noise ratio ensuring a high detection selectivity. The spectral content depends on the amount of energy released during the discharge. For an energy density of 5 kJ/m, the dominant contribution lies between 50 and 80 Hz; for 500 kJ/m, it shifts to lower frequencies between 10 and 30 Hz.

The annual amount of lightning in just 20 minutes: the October 25th, 2015 super-cell thunderstorm over central Israel

NASA Astrophysics Data System (ADS)

Yair, Y.; Ziv, B.; Lynn, B. H.; Evgeni, K.

2016-12-01

An exceptionally rare Eastern Mediterranean super-cell thunderstorm occurred during the morning hours of October 25th 2015. The storm developed within the northern tip of a Red-Sea trough (extending from Sudan to the Southeastern Mediterranean Sea) off the Egyptian coastline near Alexandria and moved north-west, crossing the Israeli coast just north of Tel-Aviv at 0900 local time. Deep convective cells developed rapidly over the sea, with thunderclouds exhibiting cloud top temperatures colder than -70°C (18 km) and radar reflectivity cores > 65 dBz at 10 km. The storms were accompanied by intensive lightning activity, severe hail, downbursts, and intense rain. The super-cell subsided upon reaching the Jordan rift in eastern Israel. The super-cell caused 1 fatality, extensive flooding and agricultural damages. It also impacted the national electrical network with power outages lasting for 3 days in central Israel. More than 17,000 cloud-to-ground lightning strokes were registered by the lightning detection system of the Israeli Electrical Corporation, exceeding the annual average for the entire country. The average cloud-to-ground flash rates between 0940-0950 and 0950-1000 (local time) were greater than 436 and 430 strokes per minute respectively, exceeding the global record flash rates found in the Argentina-Paraguay border (Zipser et al., 2006). This was the most powerful thunderstorm ever observed in Israel since lightning detection became operational in 1997. Medium-range forecast models such as ECMWF and the GFS missed the timing and severity of this unusual storm. We will present a mesoscale and microphysical analysis of this event to better understand the origins and severity of this rare super-cell. WRF high-resolution simulations with lightning assimilation (Fierro et al., 2012; Lynn et al., 2015) coupled with the Dynamic Lightning Scheme (Lynn et al., 2012) will be used in order to evaluate the performance of the WRF for accurately nowcasting such events.

An overview of VHF lightning observations by digital interferometry from ISS/JEM-GLIMS

NASA Astrophysics Data System (ADS)

Morimoto, Takeshi; Kikuchi, Hiroshi; Sato, Mitsuteru; Ushio, Tomoo; Yamazaki, Atsushi; Suzuki, Makoto; Ishida, Ryohei; Sakamoto, Yuji; Yoshida, Kazuya; Hobara, Yasuhide; Sano, Takuki; Abe, Takumi; Kawasaki, Zen-Ichiro

2016-08-01

The Global Lightning and sprIte MeasurementS (GLIMS) mission has been conducted at the Exposed Facility of Japanese Experiment Module (JEM-EF) of the International Space Station for more than 30 months. This paper focuses on an electromagnetic (EM) payload of JEM-GLIMS mission, the very high frequency (VHF) broadband digital InTerFerometer (VITF). The JEM-GLIMS mission is designed to conduct comprehensive observations with both EM and optical payloads for lightning activities and related transient luminous events. Its nominal operation continued from November 2012 to December 2014. The extended operation followed for eight months. Through the operation period, the VITF collected more than two million VHF EM waveforms in almost 18,700 datasets. The number of VITF observations synchronized with optical signal is 8049. Active VHF radiations are detected in about 70 % of optical observations without obvious regional or seasonal dependency. Estimations of the EM direction-of-arrival (DOA) are attempted using the broadband digital interferometry. Some results agree with the optical observations, even though DOA estimation is problematic because of a very short antenna baseline and multiple pulses over a short time period, namely burst-type EM waveforms. The world's first lightning observations by means of space-borne VHF interferometry are achieved in this mission. This paper summarizes VITF instruments, the recorded VHF EM signals, and the results of DOA estimations by means of digital interferometry as a preliminary report after termination of the mission.[Figure not available: see fulltext.

Polarimetric and Multi-Doppler Radar Observations of Sprite-producing Storms

NASA Technical Reports Server (NTRS)

Lang, TImothy J.; Lyons, Walter A.; Rutledge, Steven A.; Dolan, Brenda; Cummer, Steven A.; Krehbiel, Paul; Rison, William

2014-01-01

Sprites are caused by luminous electrical breakdown of the upper atmosphere, and frequently occur over large mesoscale precipitation systems. Two sprite-producing storms (on 8 and 25 June) were observed in Colorado during the summer of 2012. Unlike most past studies of sprites, these storms were observed by a polarimetric radar - the CSU-CHILL facility - which provided both PPI and RHI scans of the cases. Also available were multiple-Doppler syntheses from CSU-CHILL, local NEXRAD radars, and the CSU-Pawnee radar; as well as data from the Colorado Lightning Mapping Array (COLMA), high speed cameras, and other lightning-detection instrumentation. This unique dataset provided an unprecedented look at the detailed kinematic and microphysical structures of the thunderstorms as they produced sprites, including electrical alignment signatures in the immediate location of the charge layers neutralized by sprite-parent positive cloud-to-ground lightning strokes. One of the sprite-producing cases (25 June) featured an anomalous charge structure and may serve as a model for how sprites can be produced over convection rather than the more typical stratiform regions. Also to be presented will be evidence for advection of charge into a common stratiform precipitation region (on 8 June), which was then tapped by lightning originating from multiple different convective cores to produce sprites. Depending on the outcome of the 2013 convective season, polarimetric data from additional storms that produce sprites and other transient luminous events (TLEs) may be presented.

Nowcast of thunderstorm and typhoon activity based on lightning detection and flexible operation of micro-satellites

NASA Astrophysics Data System (ADS)

Takahashi, Y.

2016-12-01

It has become known that lightning activity represents the thunderstorm activity, namely, the intensity and area of precipitation and/or updraft. Thunderstorm is also important as a proxy of the energy input from ocean to atmosphere in typhoon, meaning that if we could monitor the thunderstorm with lightning we could predict the maximum wind velocity near the typhoon center by one or two days before. Constructing ELF and VLF radio wave observation network in Southeast Asia (AVON) and a regional dense network of automated weather station in a big city, we plan to establish the monitoring system for thunderstorm development in western pacific warm pool (WPWP) where typhoon is formed and in detail in big city area. On the other hand, some developing countries in SE-Asia are going to own micro-satellites dedicated to meteorological remote sensing. Making use of the lightning activity data measured by the ground-based networks, and information on 3-D structures of thunderclouds observed by the flexible on-demand operation of the remote-sensing micro-satellites, we would establish a new methodology to obtain very detail semi-real time information that cannot be achieved only with existing observation facilities, such as meteorological radar or large meteorological satellite. Using this new system we try to issue nowcast for the local thunderstorm and for typhoons. The first attempt will be carried out in Metro Manila in Philippines and WPWP as one of the SATREPS projects.

Phosphine and methylphosphine production by simulated lightning—a study for the volatile phosphorus cycle and cloud formation in the earth atmosphere

NASA Astrophysics Data System (ADS)

Glindemann, Dietmar; Edwards, Marc; Schrems, Otto

Phosphine (PH 3), was recently found worldwide even in the remote atmosphere (Naturwissenschaften83(1996a)131; Atmos. Environ. 37(2003)24 29). It is of interest to find natural mechanisms which could produce phosphine gas and drive a volatile link of the atmospheric phosphorus cycle and the formation of phosphoric acid as possible condensation nuclei for clouds. Here, we report on simulated lightning exposing sodium phosphate in a reducing medium (methane model atmosphere or organic matter) for 5 s to a spark induced by microwave. The gas product analyzed by gas chromatography contained phosphine (yield up to 0.6 g kg -1 phosphate P) and methylphosphine (CH 3)PH 2 (yield up to 0.02 g kg -1 phosphate P). We suggest a plasma-chemical formation mechanism where organic compounds or methane or secondary hydrogen thereof reduce phosphate to phosphine of which a small fraction can subsequently react with methyl radicals to form methylphosphine. A small yield of 6 mg phosphine per kg phosphate P was even obtained in methane free medium, by simple plasmatic recombination of inorganic phosphorus. We believe that methane and hydrogen are useful model substances of pyrolytic gases with high reducing power which may form if lightning strikes biomass, soil and aerosol. These results suggest evidence that phosphine and methylphosphine (detectable in the field by intense garlic odor) are produced when atmospheric lightning strikes the ground or aerosol which is containing oxidized forms of phosphorus and chemical reductants. Additional reviewed data show that laboratory lightning was able to reduce a much more significant portion of phosphate to phosphite (up to 25% yield), methylphosphonic acid (up to 8.5% yield) and traces of hypophosphite in a matter of seconds.

A unified radiative magnetohydrodynamics code for lightning-like discharge simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Qiang, E-mail: cq0405@126.com; Chen, Bin, E-mail: emcchen@163.com; Xiong, Run

2014-03-15

A two-dimensional Eulerian finite difference code is developed for solving the non-ideal magnetohydrodynamic (MHD) equations including the effects of self-consistent magnetic field, thermal conduction, resistivity, gravity, and radiation transfer, which when combined with specified pulse current models and plasma equations of state, can be used as a unified lightning return stroke solver. The differential equations are written in the covariant form in the cylindrical geometry and kept in the conservative form which enables some high-accuracy shock capturing schemes to be equipped in the lightning channel configuration naturally. In this code, the 5-order weighted essentially non-oscillatory scheme combined with Lax-Friedrichs fluxmore » splitting method is introduced for computing the convection terms of the MHD equations. The 3-order total variation diminishing Runge-Kutta integral operator is also equipped to keep the time-space accuracy of consistency. The numerical algorithms for non-ideal terms, e.g., artificial viscosity, resistivity, and thermal conduction, are introduced in the code via operator splitting method. This code assumes the radiation is in local thermodynamic equilibrium with plasma components and the flux limited diffusion algorithm with grey opacities is implemented for computing the radiation transfer. The transport coefficients and equation of state in this code are obtained from detailed particle population distribution calculation, which makes the numerical model is self-consistent. This code is systematically validated via the Sedov blast solutions and then used for lightning return stroke simulations with the peak current being 20 kA, 30 kA, and 40 kA, respectively. The results show that this numerical model consistent with observations and previous numerical results. The population distribution evolution and energy conservation problems are also discussed.« less

A Study of Parameters of the Counterpropagating Leader and its Influence on the Lightning Protection of Objects Using Large-Scale Laboratory Modeling

NASA Astrophysics Data System (ADS)

Syssoev, V. S.; Kostinskiy, A. Yu.; Makalskiy, L. M.; Rakov, A. V.; Andreev, M. G.; Bulatov, M. U.; Sukharevsky, D. I.; Naumova, M. U.

2014-04-01

In this work, the results of experiments on initiating the upward and descending leaders during the development of a long spark when studying lightning protection of objects with the help of large-scale models are shown. The influence of the counterpropagating leaders on the process of the lightning strike of ground-based and insulated objects is discussed. In the first case, the upward negative leader is initiated by the positive downward leader, which propagates from the high-voltage electrode of the "rod-rod"-type Marx generator (the rod is located on the plane and is 3-m high) in the gap with a length of 9-12 m. The positive-voltage pulse with a duration of 7500 μs had an amplitude of up to 3 MV. In the second case, initiation of the positive upward leader was performed in the electric field created by a cloud of negatively charged aerosol, which simulates the charged thunderstorm cell. In this case, all the phases characteristic of the ascending lightnings initiated by the tall ground-based objects and the triggered lightnings during the experiments with an actual thunderstorm cloud were observed in the forming spark discharge with a length of 1.5-2.0 m. The main parameters of the counterpropagating leader, which is initiated by the objects during the large-scale model experiments with a long spark, are shown.

Laser decontamination of the radioactive lightning rods

NASA Astrophysics Data System (ADS)

Potiens, A. J.; Dellamano, J. C.; Vicente, R.; Raele, M. P.; Wetter, N. U.; Landulfo, E.

2014-02-01

Between 1970 and 1980 Brazil experienced a significant market for radioactive lightning rods (RLR). The device consists of an air terminal with one or more sources of americium-241 attached to it. The sources were used to ionize the air around them and to increase the attraction of atmospheric discharges. Because of their ineffectiveness, the nuclear regulatory authority in Brazil suspended the license for manufacturing, commerce and installation of RLR in 1989, and determined that the replaced RLR were to be collected to a centralized radioactive waste management facility for treatment. The first step for RLR treatment is to remove the radioactive sources. Though they can be easily removed, some contaminations are found all over the remaining metal scrap that must decontaminated for release, otherwise it must be treated as radioactive waste. Decontamination using various chemicals has proven to be inefficient and generates large amounts of secondary wastes. This work shows the preliminary results of the decontamination of 241Am-contaminated metal scrap generated in the treatment of radioactive lightning rods applying laser ablation. A Nd:YAG nanoseconds laser was used with 300 mJ energy leaving only a small amount of secondary waste to be treated.

Electric discharge synthesis of HCN in simulated Jovian atmospheres

NASA Technical Reports Server (NTRS)

Stribling, Roscoe; Miller, Stanley L.

1987-01-01

Corona discharge is presently considered as a possible source of the HCN detected in the Jovian atmosphere at 2.2 x 10 to the -7th moles/sq cm column density, for the cases of gas mixtures containing H2, CH4, and NH3, with H2/CH4 ratios from 4.4 to 1585. A 3:1 ratio of corona discharge to lightning energy similar to that of the earth is applied to Jupiter. Depending on the lightning energy available on Jupiter and the eddy diffusion coefficients in the synthesis region, HCN column densities generated by corona discharge could account for about 10 percent of the HCN observed.

Laser-induced artificial fulgurites

NASA Astrophysics Data System (ADS)

Bidin, Noriah; Marsin Sanagi, Mohd; Farah, Mohammed; Naqiuddin Razali, M.; Khamis, Jamil

2018-07-01

Fulgurite is a natural glass created by lightning. Naturally it can be found at beaches or in deserts. Artificial fulgurite is created by immersing high-voltage electrodes in a tab of sand. Commonly, fulgurite is of interest among geoscientists, but its applications are still unknown. In the present paper, the concept of natural fulgurite generation is simulated to induce artificial fulgurite. Instead of lightning, a high-power laser beam is used as a source of transient heating. Syntactic sand from agrowaste is used as target material. Artificial fulgurite is generated after transient heating from a laser beam. The benefit of this finding can be used to extract silica from rice husk ash using laser technology.

Lightning protection guidelines and test data for adhesively bonded aircraft structures

NASA Technical Reports Server (NTRS)

Pryzby, J. E.; Plumer, J. A.

1984-01-01

The highly competitive marketplace and increasing cost of energy has motivated manufacturers of general aviation aircraft to utilize composite materials and metal-to-metal bonding in place of conventional fasteners and rivets to reduce weight, obtain smoother outside surfaces and reduce drag. The purpose of this program is protection of these new structures from hazardous lightning effects. The program began with a survey of advance-technology materials and fabrication methods under consideration for future designs. Sub-element specimens were subjected to simulated lightning voltages and currents. Measurements of bond line voltages, electrical sparking, and mechanical strength degradation were made to comprise a data base of electrical properties for new technology materials and basic structural configurations. The second hase of the program involved tests on full scale wing structures which contained integral fuel tanks and which were representative of examples of new technology structures and fuel systems. The purpose of these tests was to provide a comparison between full scale structural measurements and those obtained from the sub-element specimens.

Data and results of a laboratory investigation of microprocessor upset caused by simulated lightning-induced analog transients

NASA Technical Reports Server (NTRS)

Belcastro, C. M.

1984-01-01

A methodology was developed a assess the upset susceptibility/reliability of a computer system onboard an aircraft flying through a lightning environment. Upset error modes in a general purpose microprocessor were studied. The upset tests involved the random input of analog transients which model lightning induced signals onto interface lines of an 8080 based microcomputer from which upset error data was recorded. The program code on the microprocessor during tests is designed to exercise all of the machine cycles and memory addressing techniques implemented in the 8080 central processing unit. A statistical analysis is presented in which possible correlations are established between the probability of upset occurrence and transient signal inputs during specific processing states and operations. A stochastic upset susceptibility model for the 8080 microprocessor is presented. The susceptibility of this microprocessor to upset, once analog transients have entered the system, is determined analytically by calculating the state probabilities of the stochastic model.

Characteristics of M-component in rocket-triggered lightning and a discussion on its mechanism

NASA Astrophysics Data System (ADS)

Jiang, Rubin; Qie, Xiushu; Yang, Jing; Wang, Caixia; Zhao, Yang

2013-09-01

The current and electric field pulses associated with M-component following dart leader-return stroke sequences in negative rocket-triggered lightning flashes were analyzed in detail by using the data from Shandong Artificially Triggering Lightning Experiment, conducted from 2005 to 2010. For 63 M-components with current waveforms superimposed on the relatively steady continuing current, the geometric mean values of the peak current, duration, and charge transfer were 276 A, 1.21 ms, and 101 mC, respectively. The behaviors of the channel base current versus close electric field changes and the observation facts by different authors were carefully examined for investigation on mechanism of the M-component. A modified model based on Rakov's "two-wave" theory is proposed and confirms that the evolution of M-component through the lightning channel involves a downward wave transferring negative charge from the upper to the lower channel and an upward wave draining the charge transported by the downward wave. The upward wave serves to deplete the negative charge by the downward wave at its interface and makes the charge density of the channel beneath the interface layer to be roughly zero. Such modified concept is recognized to be reasonable by the simulated results showing a good agreement between the calculated and the measured E-field waveforms.

Ball Lightning–Aerosol Electrochemical Power Source or A Cloud of Batteries

PubMed Central

2007-01-01

Despite numerous attempts, an adequate theoretical and experimental simulation of ball lightning still remains incomplete. According to the model proposed here, the processes of electrochemical oxidation within separate aerosol particles are the basis for this phenomenon, and ball lightning is a cloud of composite nano or submicron particles, where each particle is a spontaneously formed nanobattery which is short-circuited by the surface discharge because it is of such a small size. As free discharge-shorted current loops, aerosol nanobatteries are exposed to a powerful mutual magnetic dipole–dipole attraction. The gaseous products and thermal energy produced by each nanobattery as a result of the intra-particle self-sustaining electrochemical reactions, cause a mutual repulsion of these particles over short distances and prevent their aggregation, while a collectivization of the current loops of separate particles, due to the electric arc overlapping between adjacent particles, weakens their mutual magnetic attraction over short distances. Discharge currents in the range of several amperes to several thousand amperes as well as the pre-explosive mega ampere currents, generated in the reduction–oxidation reactions and distributed between all the aerosol particles, explain both the magnetic attraction between the elements of the ball lightning substance and the impressive electromagnetic effects of ball lightning.

Current Distribution Characteristics of CFRP Panels

NASA Astrophysics Data System (ADS)

Yamamoto, Kazuo

CFRP (Carbon Fiber Reinforced Plastic) is widely used in the structures of aircrafts, automobiles, wing turbines, and rockets because of its qualities of high mechanical strength, low weight, fatigue resistance, and dimensional stability. However, these structures are often at risk of being struck by lightning. When lightning strikes such structures and lightning current flows through the CFRP, it may be structurally damaged because of the impact of the lightning strike or ignitions between layers. If there are electronic systems near the CFRP, they may break down or malfunction because of the resulting electromagnetic disturbance. In fact, the generation mechanisms of these breakdowns and malfunctions depend on the current distribution in the CFRP. Hence, it is critical to clarify the current distribution in various kinds of CFRPs. In this study, two kinds of CFRP panels—one composed of quasi-isotropic lamination layers and the other composed of 0°/90° lamination layers of unidirectional CFRP prepregs—are used to investigate the dependence of current distribution on the nature of the lamination layers. The current distribution measurements and simulations for CFRP panels are compared with those for a same-sized aluminum plate. The knowledge of these current distribution characteristics would be very useful for designing the CFRP structures of aircrafts, automobiles, wing turbines, rockets, etc. in the future.

Detection of Lightning-produced NOx by Air Quality Monitoring Stations in Israel

NASA Astrophysics Data System (ADS)

Yair, Y.; Shalev, S.; Saaroni, H.; Ziv, B.

2011-12-01

Lightning is the largest natural source for the production of nitrogen oxides (LtNOx) in the troposphere. Since NOx are greenhouse gases, it is important to know the global production rate of LtNOx for climate studies (present estimates range from 2 to 8 Tg per year) and to model its vertical distribution (Ott et al., 2010). One of the key factors for such an estimate is the yield of a single lightning flash, namely the number of molecules produced for each Joule of energy deposited along the lightning channel. We used lightning stroke data from the Israel Lightning Location System (ILLS) together with NOx data obtained from the national network of air quality monitoring stations operated by the Israeli Ministry of Environmental Protection. Looking for the fingerprints of LtNOx in the general ambient concentrations, usually most affected by pollution from urban sources, we looked only for CG strokes occurring within a radius of 3 km from the location of an air-quality monitoring station. This lowered the number of relevant cases from 605,413 strokes detected in the 2004/5 through 2009/10 seasons to 1,897 strokes. We applied a threshold of > 60kA reducing the number of events to 35. The results showed that there was no consistent rising trend in the NOx concentrations in the hour following the lightning (the lifetime near the ground is expected to be a few hours; Zhang et al., 2003). However, when considering only those events when the prevailing wind was in the direction from the stroke location toward the sensor (7 cases), a clear increase of few ppb following the stroke was observed in 5 cases [see Fig.]. This increase is well correlated with the wind speed, suggesting an effective transport from the stroke location to the sensor. Weaker winds allow dilution and result in smaller observed increases of LtNOx. Separate analysis of additional 17 cases in which the strokes were located < 500 m from the monitoring station (with any peak current above 7 kA) showed no consistent trend. When excluding the 7 events that occurred during rush hour traffic, we found 6 (of 10) cases with an average increase in NOx concentrations of 16 ppb in the hour following the lightning. These results suggest a contribution of CG lightning strokes to the ground level concentrations of NOx. L. E. Ott, K. E. Pickering, G. L. Stenchikov, D. J. Allen, A. J. DeCaria, B. Ridley, R.F. Lin, S. Lang, and W.K. Tao (2010), Production of lightning NOx and its vertical distribution calculated from three dimensional cloud scale chemical transport model simulations, J. Geophys. Res., 115, D04301, doi:10.1029/2009JD011880

Seasonal and Local Characteristics of Lightning Outages of Power Distribution Lines in Hokuriku Area

NASA Astrophysics Data System (ADS)

Sugimoto, Hitoshi; Shimasaki, Katsuhiko

The proportion of the lightning outages in all outages on Japanese 6.6kV distribution lines is high with approximately 20 percent, and then lightning protections are very important for supply reliability of 6.6kV lines. It is effective for the lightning performance to apply countermeasures in order of the area where a large number of the lightning outages occur. Winter lightning occurs in Hokuriku area, therefore it is also important to understand the seasonal characteristics of the lightning outages. In summer 70 percent of the lightning outages on distribution lines in Hokuriku area were due to sparkover, such as power wire breakings and failures of pole-mounted transformers. However, in winter almost half of lightning-damaged equipments were surge arrester failures. The number of the lightning outages per lightning strokes detected by the lightning location system (LLS) in winter was 4.4 times larger than that in summer. The authors have presumed the occurrence of lightning outages from lightning stroke density, 50% value of lightning current and installation rate of lightning protection equipments and overhead ground wire by multiple regression analysis. The presumed results suggest the local difference in the lightning outages.

Modern concepts of treatment and prevention of lightning injuries.

PubMed

Edlich, Richard F; Farinholt, Heidi-Marie A; Winters, Kathryne L; Britt, L D; Long, William B

2005-01-01

Lightning is the second most common cause of weather-related death in the United States. Lightning is a natural atmospheric discharge that occurs between regions of net positive and net negative electric charges. There are several types of lightning, including streak lightning, sheet lightning, ribbon lightning, bead lightning, and ball lightning. Lightning causes injury through five basic mechanisms: direct strike, flash discharge (splash), contact, ground current (step voltage), and blunt trauma. While persons struck by lightning show evidence of multisystem derangement, the most dramatic effects involve the cardiovascular and central nervous systems. Cardiopulmonary arrest is the most common cause of death in lightning victims. Immediate resuscitation of people struck by lightning greatly affects the prognosis. Electrocardiographic changes observed following lightning accidents are probably from primary electric injury or burns of the myocardium without coronary artery occlusion. Lightning induces vasomotor spasm from direct sympathetic stimulation resulting in severe loss of pulses in the extremities. This vasoconstriction may be associated with transient paralysis. Damage to the central nervous system accounts for the second most debilitating group of injuries. Central nervous system injuries from lightning include amnesia and confusion, immediate loss of consciousness, weakness, intracranial injuries, and even brief aphasia. Other organ systems injured by lightning include the eye, ear, gastrointestinal system, skin, and musculoskeletal system. The best treatment of lightning injuries is prevention. The Lightning Safety Guidelines devised by the Lightning Safety Group should be instituted in the United States and other nations to prevent these devastating injuries.

Analysis of the lightning-attractive radius for wind turbines considering the developing process of positive attachment leader

NASA Astrophysics Data System (ADS)

Yang, Ning; Zhang, Qilin; Hou, Wenhao; Wen, Ying

2017-03-01

In this paper, we have presented the upward leader propagation model, considering the transition of stream leader process by the finite element method and analyzing the inception and subsequent physical processes of upward leader and the attractive radius for large wind turbines. For validating our model, the comparison of simulated results with the optically high-speed video observation shows that the model can predict an accepted result of upward leader from a 163 m tall tower, the simulated upward leader velocity and length before final jump are 2.3 × 105 m/s and 187.67 m presented by Warner (2010), which are very similar to the observed results of 2.8 × 105 m/s and 184 m, respectively. At the same time, we find that the assumed constant speed ratio of downward/upward leader is improper and cannot accurately predict the attractive radius by lightning strike. Also, the simulated results are compared with the widely used EGM (electro geometric model), and it is found that the EGM has an obvious underestimation of attractive radius more than 50%.

Produce documents and media information. [on lightning

NASA Technical Reports Server (NTRS)

Alzmann, Melanie A.; Miller, G.A.

1994-01-01

Lightning data and information were collected from the United States, Germany, France, Brazil, China, and Australia for the dual purposes of compiling a global lightning data base and producing publications on the Marshall Space Flight Center's lightning program. Research covers the history of lightning, the characteristics of a storm, types of lightningdischarges, observations from airplanes and spacecraft, the future fole of planes and spacecraft in lightning studies, lightning detection networks, and the relationships between lightning and rainfall. Descriptions of the Optical Transient Dectector, the Lightning Imaging Sensor, and the Lightning Mapper Sensor are included.

Sensitivity of an Integrated Mesoscale Atmosphere and Agriculture Land Modeling System (WRF/CMAQ-EPIC) to MODIS Vegetation and Lightning Assimilation

NASA Astrophysics Data System (ADS)

Ran, L.; Cooter, E. J.; Gilliam, R. C.; Foroutan, H.; Kang, D.; Appel, W.; Wong, D. C.; Pleim, J. E.; Benson, V.; Pouliot, G.

2017-12-01

The combined meteorology and air quality modeling system composed of the Weather Research and Forecast (WRF) model and Community Multiscale Air Quality (CMAQ) model is an important decision support tool that is used in research and regulatory decisions related to emissions, meteorology, climate, and chemical transport. The Environmental Policy Integrated Climate (EPIC) is a cropping model which has long been used in a range of applications related to soil erosion, crop productivity, climate change, and water quality around the world. We have integrated WRF/CMAQ with EPIC using the Fertilizer Emission Scenario Tool for CMAQ (FEST-C) to estimate daily soil N information with fertilization for CMAQ bi-directional ammonia flux modeling. Driven by the weather and N deposition from WRF/CMAQ, FEST-C EPIC simulations are conducted on 22 different agricultural production systems ranging from managed grass lands (e.g. hay and alfalfa) to crop lands (e.g. corn grain and soybean) with rainfed and irrigated information across any defined conterminous United States (U.S.) CMAQ domain and grid resolution. In recent years, this integrated system has been enhanced and applied in many different air quality and ecosystem assessment projects related to land-water-atmosphere interactions. These enhancements have advanced this system to become a valuable tool for integrated assessments of air, land and water quality in light of social drivers and human and ecological outcomes. This presentation will focus on evaluating the sensitivity of precipitation and N deposition in the integrated system to MODIS vegetation input and lightning assimilation and their impacts on agricultural production and fertilization. We will describe the integrated modeling system and evaluate simulated precipitation and N deposition along with other weather information (e.g. temperature, humidity) for 2011 over the conterminous U.S. at 12 km grids from a coupled WRF/CMAQ with MODIS and lightning assimilation. Simulated agricultural production and fertilization from FEST-C EPIC driven by the changed meteorology and N deposition from MODIS and lightning assimilations will be evaluated and analyzed.

Interaction with the lower ionosphere of electromagnetic pulses from lightning - Heating, attachment, and ionization

NASA Technical Reports Server (NTRS)

Taranenko, Y. N.; Inan, U. S.; Bell, T. F.

1993-01-01

A Boltzmann formulation of the electron distribution function and Maxwell's equations for the EM fields are used to simulate the interaction of lightning radiated EM pulses with the lower ionosphere. Ionization and dissociative attachment induced by the heated electrons cause significant changes in the local electron density, N(e). Due to 'slow' field changes of typical lightning EM pulses over time scales of tens of microsec, the distribution function follows the quasi-equilibrium solution of the Boltzmann equation in the altitude range of interest (70 to 100 km). The EM pulse is simulated as a planar 100 microsec long single period oscillation of a 10 kHz wave injected at 70 km. Under nighttime conditions, individual pulses of intensity 10-20 V/m (normalized to 100 km horizontal distance) produce changes in N(e) of 1-30 percent while a sequence of pulses leads to strong modification of N(e) at altitudes less than 95 km. The N(e) changes produce a 'sharpening' of the lower ionospheric boundary by causing a reduction in electron density at 75-85 km (due to attachment) and a substantial increase at 85-95 km (due to ionization) (e.g., the scale height decreases by a factor of about 2 at about 85 km for a single 20 V/m EM pulse). No substantial N(e) changes occur during daytime.

A comparison between initial continuous currents of different types of upward lightning

NASA Astrophysics Data System (ADS)

Wang, D.; Sawada, N.; Takagi, N.

2009-12-01

We have observed the lightning to a wind turbine and its lightning-protection tower for four consecutive winter seasons from 2005 to 2009. Our observation items include (1) thunderstorm electrical fields and lightning-caused electric field changes at multi sites around the wind turbine, (2) electrical currents at the bottom of the wind turbine and its lightning protection tower, (3) normal video and high speed image of lightning optical channels. Totally, we have obtained the data for 42 lightning that hit either on wind turbine or its lightning protection tower or both. Among these 42 lightning, 38 are upward lightning and 2 are downward lightning. We found the upward lightning can be sub-classified into two types. Type 1 upward lightning are self-triggered from a high structure, while type 2 lightning are triggered by a discharge occurred in other places which could be either a cloud discharge or a cloud-to-ground discharge (other-triggered). In this study, we have compared the two types of upward lightning in terms of initial continuous current rise time, peak current and charge transferred to the ground. We found that the initial current of self-triggered lightning tends to rise significantly faster and to a bigger peak value than the other-triggered lightning, although both types of lightning transferred similar amount of charge to the ground.

KSC-2013-2815

NASA Image and Video Library

2013-06-17

CAPE CANAVERAL, Fla. -- An ominous storm cloud hovers over Launch Complex 39 at NASA's Kennedy Space Center in Florida. The massive, 525-foot-tall facility at left is the Vehicle Assembly Building. Florida summers are known for their dynamic weather patterns with the start of the Atlantic hurricane season and the onset of afternoon thunderstorms that bring with them heavy rain, frequent lightning and occasionally even tornadoes. Photo credit: NASA/Jim Grossmann

Spatial and Temporal Ionospheric Monitoring Using Broadband Sferic Measurements

NASA Astrophysics Data System (ADS)

McCormick, J. C.; Cohen, M. B.; Gross, N. C.; Said, R. K.

2018-04-01

The D region of the ionosphere (60-90 km altitude) is highly variable on timescales from fractions of a second to many hours, and on spatial scales up to many hundreds of kilometers. Very low frequency (VLF) and low-frequency (LF) (3-30 kHz and 30-300 kHz) radio waves are guided to global distances by reflections from the ground and the D region. Therefore, information about its current state is encoded in received VLF/LF signals. VLF transmitters have been used in the past for D region studies, with ionospheric disturbances manifesting as perturbations in amplitude and/or phase. The return stroke of lightning is an impulsive VLF radiator, but unlike VLF transmitters, lightning events are distributed broadly in space allowing for much greater spatial coverage of the D region compared to VLF transmitter-based remote sensing in addition to the broadband spectral advantage over the narrowband transmitters. The challenge is that individual lightning-generated waveforms, or "sferics," vary due to the lightning current parameters and uncertainty in the time/location information, in addition to D region ionospheric variability. These factors make it difficult to utilize the VLF/LF emissions from lightning in a straightforward manner. We describe a technique to recover the time domain and amplitude/phase spectra for both Bϕ and Br with high fidelity and consider the utility of our technique with ambient and varied ionospheric conditions. We demonstrate a technique to simulate sferics and infer a parameterized ionosphere with the Wait and Spies parameters (h' and β) offering all of the tools needed for a global measurement.

Simulation of the impact of thunderstorm activity on atmospheric gas composition

NASA Astrophysics Data System (ADS)

Smyshlyaev, S. P.; Mareev, E. A.; Galin, V. Ya.

2010-08-01

A chemistry-climate model of the lower and middle atmosphere has been used to estimate the sensitivity of the atmospheric gas composition to the rate of thunderstorm production of nitrogen oxides at upper tropospheric and lower stratospheric altitudes. The impact that nitrogen oxides produced by lightning have on the atmospheric gas composition is treated as a subgrid-scale process and included in the model parametrically. The natural uncertainty in the global production rate of nitrogen oxides in lightning flashes was specified within limits from 2 to 20 Tg N/year. Results of the model experiments have shown that, due to the variability of thunderstorm-produced nitrogen oxides, their concentration in the upper troposphere and lower stratosphere can vary by a factor of 2 or 3, which, given the influence of nitrogen oxides on ozone and other gases, creates the potential for a strong perturbation of the atmospheric gas composition and thermal regime. Model calculations have shown the strong sensitivity of ozone and the OH hydroxyl to the amount of lightning nitrogen oxides at different atmospheric altitudes. These calculations demonstrate the importance of nitrogen oxides of thunderstorm origin for the balance of atmospheric odd ozone and gases linked to it, such as ozone and hydroxyl radicals. Our results demonstrate that one important task is to raise the accuracy of estimates of the rate of nitrogen oxide production by lightning discharges and to use physical parametrizations that take into account the local lightning effects and feedbacks arising in this case rather than climatological data in models of the gas composition and general circulation of the atmosphere.

Production of Ionospheric Perturbations by Cloud-to-Ground Lightning and the Recovery of the Lower Ionosphere

NASA Astrophysics Data System (ADS)

Liu, Ningyu; Dwyer, Joseph; Rassoul, Hamid

2013-04-01

The fact that lightning/thunderstorm activities can directly modify the lower ionosphere has long been established by observations of the perturbations of very low frequency (VLF) signals propagating in the earth-ionosphere waveguide. These perturbations are known as early VLF events [Inan et al., 2010, JGR, 115, A00E36, 2010]. More recently discovered transient luminous events caused by the lightning/thunderstorm activities only last ~1-100 ms, but studies of the early VLF events show that the lightning ionospheric effects can persist much longer, >10s min [Cotts and Inan, GRL, 34, L14809, 2007; Haldoupis et al., JGR, 39, L16801, 2012; Salut et al., JGR, 117, A08311, 2012]. It has been suggested that the long recovery is caused by long-lasting conductivity perturbations in the lower ionosphere, which can be created by sprites/sprite halos which in turn are triggered by cloud-to-ground (CG) lightning [Moore et al., JGR, 108, 1363, 2003; Haldoupis et al., 2012]. We recently developed a two-dimensional fluid model with simplified ionospheric chemistry for studying the quasi-electrostatic effects of lightning in the lower ionosphere [Liu, JGR, 117, A03308, 2012]. The model chemistry captures major ion species and reactions in the lower ionosphere. Additional important features of the model include self-consistent background ion density profiles and full description of electron and ion transport. In this talk, we present the simulation results on the dynamics of sprite halos caused by negative CG lightning. The modeling results indicate that electron density around 60 km altitude can be enhanced in a region as wide as 80 km. The enhancement reaches its full extent in ~1 s and recovers in 1-10 s, which are on the same orders as the durations of slow onset and post-onset peaks of some VLF events, respectively. In addition, long-lasting electron and ion density perturbations can occur around 80 km altitude due to negative halos as well as positive halos, which can explain long-recovery VLF events and step-change VLF events.

Principles of Lightning Physics

NASA Astrophysics Data System (ADS)

Mazur, Vladislav

2016-12-01

Principles of Lightning Physics presents and discusses the most up-to-date physical concepts that govern many lightning events in nature, including lightning interactions with man-made structures, at a level suitable for researchers, advanced students and well-educated lightning enthusiasts. The author's approach to understanding lightning-to seek out, and show what is common to all lightning flashes-is illustrated by an analysis of each type of lightning and the multitude of lightning-related features. The book examines the work that has gone into the development of new physical concepts, and provides critical evaluations of the existing understanding of the physics of lightning and the lexicon of terms and definitions presently used in lightning research.

Tropospheric Ozone Source Attribution in Southern California during Summer 2014 Based on Lidar Measurements and Model Simulations

NASA Technical Reports Server (NTRS)

Granados Munoz, Maria Jose; Johnson, Matthew S.; Leblanc, Thierry

2016-01-01

In the past decades, significant efforts have been made to increase tropospheric ozone long-term monitoring. A large number of ground-based, airborne and space-borne instruments are currently providing valuable data to contribute to better understand tropospheric ozone budget and variability. Nonetheless, most of these instruments provide in-situ surface and column-integrated data, whereas vertically resolved measurements are still scarce. Besides ozonesondes and aircraft, lidar measurements have proven to be valuable tropospheric ozone profilers. Using the measurements from the tropospheric ozone differential absorption lidar (DIAL) located at the JPL Table Mountain Facility, California, and the GEOS-Chem and GEOS-5 model outputs, the impact of the North American monsoon on tropospheric ozone during summer 2014 is investigated. The influence of the Monsoon lightning-induced NOx will be evaluated against other sources (e.g. local anthropogenic emissions and the stratosphere) using also complementary data such as backward-trajectories analysis, coincident water vapor lidar measurements, and surface ozone in-situ measurements.

Initial Results Derived from JEM-GLIMS Observations

NASA Astrophysics Data System (ADS)

Sato, M.; Ushio, T.; Morimoto, T.; Kobayashi, N.; Takahashi, Y.; Suzuki, M.; Yamazaki, A.; Inan, U.; Linscott, I.; Hobara, Y.

2012-12-01

In order to identify the spatial distributions and occurrence conditions of TLEs, JEM-GLIMS (Global Lightning and sprIte MeasurementS on JEM-EF) observations from Japanese Experiment Module - Exposed Facility (JEM-EF) at International Space Station (ISS) will start this year. Science instruments of JEM-GLIMS consist of two kinds of optical detectors and two kinds of radio receivers. The optical instruments are two wide FOV CMOS cameras (LSI) and six-channel spectrophotometers (PH). LSI uses a CMOS device with 512x512 pixels as an imaging sensor and uses a CCTV lens with =25 mm/F=1.4 which becomes 28.3x28.3 deg. FOV. LSI-1 equips a wide band optical filter (766-832 nm) and mainly measures lightning emission, while LSI-2 equips a narrowband optical filter (762+/-7 nm) and mainly measures TLE emission. Five of six PH channels employ the optics with 42.7 deg. conical FOV and use photomultiplier tubes (PMTs) as photon detectors. Each channel of these photometers equips an optical band-pass filter to measure N2 1P, 2P, and LBH emissions. One of six photometers employs a wide-FOV optics (86.8 deg.) and wide-band filter to measure N2 1P lightning emission. All these optical instruments are pointed to the nadir direction. In order to detect whistler wave excited by lightning discharges, one VLF receiver (VLFR) is installed. VLFR consists of a 15 cm nadir-directing monopole antenna and an electronics unit recording waveform data with a sampling frequency of 100 kHz with 14-bit resolution. In addition to this, two sets of VHF receivers (VITF) are also installed to measure VHF pulses emitted by lightning discharges. VITF consists of two patch-type antennas separated by 1.5 m and an electronics unit which records pulse data with a sampling frequency of 200 MHz with 8-bit resolution. Thus, the spatial and temporal evolution of lightning and TLEs can be measured by the two optical instruments, while the electrical characteristics of sprite-inducing lightning discharges can be measured by two radio receivers. JEM-GIMS was successfully launched by H-IIB rocket at 02:06:18 UT on July 21, 2012 and transported to ISS by the HTV-3 cargo transfer spaceship. HTV-3 successfully arrived at ISS on July 27 and our JEM-GLIMS instruments will be installed at JEM-EF on August 9. For the period from September 15 to 21 we will carry out the initial checkout operation, and finally we will start continuous TLE observations from the middle of October. At the presentation we will show the test results obtained during the checkout operations and will present the initial results derived from JEM-GLIMS lightning/TLE observations.

A Wildfire Behavior Modeling System at Los Alamos National Laboratory for Operational Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

S.W. Koch; R.G.Balice

2004-11-01

To support efforts to protect facilities and property at Los Alamos National Laboratory from damages caused by wildfire, we completed a multiyear project to develop a system for modeling the behavior of wildfires in the Los Alamos region. This was accomplished by parameterizing the FARSITE wildfire behavior model with locally gathered data representing topography, fuels, and weather conditions from throughout the Los Alamos region. Detailed parameterization was made possible by an extensive monitoring network of permanent plots, weather towers, and other data collection facilities. We also incorporated a database of lightning strikes that can be used individually as repeatable ignitionmore » points or can be used as a group in Monte Carlo simulation exercises and in other randomization procedures. The assembled modeling system was subjected to sensitivity analyses and was validated against documented fires, including the Cerro Grande Fire. The resulting modeling system is a valuable tool for research and management. It also complements knowledge based on professional expertise and information gathered from other modeling technologies. However, the modeling system requires frequent updates of the input data layers to produce currently valid results, to adapt to changes in environmental conditions within the Los Alamos region, and to allow for the quick production of model outputs during emergency operations.« less

Effects of assimilating precipitation zones derived from satellite and lightning data on numerical simulations of tropical-like Mediterranean storms

NASA Astrophysics Data System (ADS)

Fita, L.; Romero, R.; Luque, A.; Ramis, C.

2009-08-01

The scarcity of meteorological observations in maritime areas is a well-known problem that can be an important limitation in the study of different phenomena. Tropical-like storms or medicanes developed over the Mediterranean sea are intense storms with some similarities to the tropical ones. Although they do not reach the hurricane intensity, their potential for damage is very high, due to the densely populated Mediterranean coastal regions. In this study, the two notable cases of medicane development which occurred in the western Mediterranean basin in September 1996 and October 2003, are considered. The capability of mesoscale numerical models to simulate general aspects of such a phenomena has been previously shown. With the aim of improving the numerical results, an adjustment of the humidity vertical profiles in MM5 simulations is performed by means of satellite derived precipitation. Convective and stratiform precipitation types obtained from satellite images are used to individually adjust the profiles. Lightning hits are employed to identify convective grid points. The adjustment of the vertical humidity profiles is carried out in the European Centre for Medium-Range Weather Forecasts (ECMWF) analyses used as initial conditions for the simulations. Analyses nudging to ECMWF analyses and to the satellite-based humidity-corrected version of these analyses has also been applied using Four Dimensional Data Assimilation (FDDA). An additional adjustment is applied as observation nudging of satellite/lightning information at different time and spatial resolutions. Statistical parameters are proposed and tested as an objective way to intercompare satellite-derived and simulated trajectories. Simulations of medicanes exhibit a strong sensitivity to vertical humidity profiles. Trajectories of the storms are improved or worsened by using FDDA. A case dependence is obtained on the characteristics of the humidity-corrected medicanes. FDDA sensitivity on temporal and spatial resolution of the assimilated data also presents a case dependence. It also shows a significant sensitivity of the results of the observation nudging to the specific choice of the values of coefficient weight and vertical ratio of the ingested observations.

The North Alabama Lightning Warning Product

NASA Technical Reports Server (NTRS)

Buechler, Dennis E.; Blakeslee, R. J.; Stano, G. T.

2009-01-01

The North Alabama Lightning Mapping Array NALMA has been collecting total lightning data on storms in the Tennessee Valley region since 2001. Forecasters from nearby National Weather Service (NWS) offices have been ingesting this data for display with other AWIPS products. The current lightning product used by the offices is the lightning source density plot. The new product provides a probabalistic, short-term, graphical forecast of the probability of lightning activity occurring at 5 min intervals over the next 30 minutes . One of the uses of the current lightning source density product by the Huntsville National Weather Service Office is to identify areas of potential for cloud-to-ground flashes based on where LMA total lightning is occurring. This product quantifies that observation. The Lightning Warning Product is derived from total lightning observations from the Washington, D.C. (DCLMA) and North Alabama Lightning Mapping Arrays and cloud-to-ground lightning flashes detected by the National Lightning Detection Network (NLDN). Probability predictions are provided for both intracloud and cloud-to-ground flashes. The gridded product can be displayed on AWIPS workstations in a manner similar to that of the lightning source density product.

Applied Meteorology Unit Quarterly Report, Second Quarter FY-13

NASA Technical Reports Server (NTRS)

Bauman, William; Crawford, Winifred; Watson, Leela; Shafer, Jaclyn; Huddleston, Lisa

2013-01-01

The AMU team worked on six tasks for their customers: (1) Ms. Crawford continued work on the objective lightning forecast task for airports in east-central Florida, and began work on developing a dual-Doppler analysis with local Doppler radars, (2) Ms. Shafer continued work for Vandenberg Air Force Base on an automated tool to relate pressure gradients to peak winds, (3) Dr. Huddleston continued work to develop a lightning timing forecast tool for the Kennedy Space Center/Cape Canaveral Air Force Station area, (4) Dr. Bauman continued work on a severe weather forecast tool focused on east-central Florida, (5) Mr. Decker began developing a wind pairs database for the Launch Services Program to use when evaluating upper-level winds for launch vehicles, and (6) Dr. Watson began work to assimilate observational data into the high-resolution model configurations, she created for Wallops Flight Facility and the Eastern Range.

A Lightning Safety Primer for Camps.

ERIC Educational Resources Information Center

Attarian, Aram

1992-01-01

Provides the following information about lightning, which is necessary for camp administrators and staff: (1) warning signs of lightning; (2) dangers of lightning; (3) types of lightning injuries; (4) prevention of lightning injury; and (5) helpful training tips. (KS)

Ignition of Fuel Vapors Beneath Titanium Aircraft Skins Exposed to Lightning

NASA Technical Reports Server (NTRS)

Kosvic, T. C.; Helgeson, N. L.; Gerstein, M.

1971-01-01

Hot-spot and puncture ignition of fuel vapors by simulated lightning discharges was studied experimentally. The influences of skin coating, skin structure, discharge polarity, skin thickness, discharge current level, and current duration were measured and interpreted. Ignition thresholds are reported for titanium alloy constructed as sheets, sheets coated with sealants, and sandwich skins. Results indicated that the ignition threshold charge transfer for coated sheets, honeycomb, and truss skins is respectively about 200%, 400%, 800% that of bare alloy sheet of .102 cm (.040 in.)-thickness. It was found that hot-spot ignition can occur well after termination of the arc, and that sandwich materials allow ignition only if punctured.

Do canopy disturbances drive forest plantations into more natural conditions? — A case study from Can Gio Biosphere Reserve, Viet Nam

NASA Astrophysics Data System (ADS)

Vogt, Juliane; Kautz, Markus; Fontalvo Herazo, Martha Liliana; Triet, Tran; Walther, Denny; Saint-Paul, Ulrich; Diele, Karen; Berger, Uta

2013-11-01

Large areas of mangrove forests were devastated in South Viet Nam during the second Indochina war. After its end in 1975, extensive reforestation with monocultures took place. Can Gio, one of the biggest replanted sites with about 20,000 ha of mangroves mainly Rhizophora apiculata, was declared a biosphere reserve by the UNESCO in 2000. Although this status now enables progressive forest dynamics, there are still drawbacks resulting from the unnatural character of the plantations. For example, the homogeneous size and age structure as well as the regular arrangement of the planted trees make larger forest stands more vulnerable to synchronized collapsing which can be triggered by stronger winds and storms. A transformation into a more natural forest characterized by a heterogeneous age and size structure and a mixed species composition is of urgent need to avoid a synchronized dieback. In this study we test the capability of natural canopy disturbances (e.g. lightning strikes) to facilitate this transformation.Canopy gaps created by lightning strikes were detected and quantified by remote sensing techniques. SPOT satellite images from the years 2003, 2005 and 2007 provided information about the spatial distribution, size, shape, and formation frequency of the gaps. Lightning strike gaps were identified based on their shape and size. They form small openings (mean: 0.025 ha) and their yearly probability of occurrence was determined to be approximately 0.012 per hectare. Selected gaps were surveyed in the field in 2008 to complement the remote sensing data and to provide information upon forest structure and regeneration.Simulation experiments were carried out with the individual-based KiWi mangrove model for quantifying the influence of different lightning regimes on the vertical and horizontal structure of the R. apiculata plantation. In addition, we conducted simulations with a natural and thus randomly generated forest to compare the structure of the two different cultivation types (i.e. plantation and natural forest). The simulation shows that even small disturbances can already partly buffer the risk of cohort senescence of monospecific even-aged plantations. However, after the decline of the plantation, the disturbance regime does not play an important role for further stand development. After the break-up of the initial strongly regular structure of the simulated plantation, a vertical pattern, i.e. height distribution of the trees, similar to the one of the natural forest, emerged quickly. However, the convergence for the horizontal structure i.e. the distance of trees to their nearest neighbor, took twice as long as for the vertical structure. Our results highlight the importance of small disturbances such as lightning strikes to mitigate vulnerability against synchronous windfall in homogenous forest structures. Hence, creating small openings artificially may be an appropriate management measure in areas where the frequency of natural small-scale disturbances is low.

The Intra-Cloud Lightning Fraction in the Contiguous United States

NASA Technical Reports Server (NTRS)

Medici, Gina; Cummins, Kenneth L.; Koshak, William J.; Rudlosky, Scott D.; Blakeslee, Richard J.; Goodman, Steven J.; Cecil, Daniel J.; Bright, David R.

2015-01-01

Lightning is dangerous and destructive; cloud-to-ground (CG) lightning flashes can start fires, interrupt power delivery, destroy property and cause fatalities. Its rate-of-occurrence reflects storm kinematics and microphysics. For decades lightning research has been an important focus, and advances in lightning detection technology have been essential contributors to our increasing knowledge of lightning. A significant step in detection technology is the Geostationary Lightning Mapper (GLM) to be onboard the Geostationary Operational Environment Satellite R-Series (GOES-R) to be launched in early 2016. GLM will provide continuous "Total Lightning" observations [CG and intra-cloud lightning (IC)] with near-uniform spatial resolution over the Americas by measuring radiance at the cloud tops from the different types of lightning. These Total Lightning observations are expected to significantly improve our ability to nowcast severe weather. It may be important to understand the long-term regional differences in the relative occurrence of IC and CG lightning in order to understand and properly use the short-term changes in Total Lightning flash rate for evaluating individual storms.

[Relationships of forest fire with lightning in Daxing' anling Mountains, Northeast China].

PubMed

Lei, Xiao-Li; Zhou, Guang-Sheng; Jia, Bing-Rui; Li, Shuai

2012-07-01

Forest fire is an important factor affecting forest ecosystem succession. Recently, forest fire, especially forest lightning fire, shows an increasing trend under global warming. To study the relationships of forest fire with lightning is essential to accurately predict the forest fire in time. Daxing' anling Mountains is a region with high frequency of forest lightning fire in China, and an important experiment site to study the relationships of forest fire with lightning. Based on the forest fire records and the corresponding lightning and meteorological observation data in the Mountains from 1966 to 2007, this paper analyzed the relationships of forest fire with lightning in this region. In the period of 1966-2007, both the lightning fire number and the fired forest area in this region increased significantly. The meteorological factors affecting the forest lighting fire were related to temporal scales. At yearly scale, the forest lightning fire was significantly correlated with precipitation, with a correlation coefficient of -0.489; at monthly scale, it had a significant correlation with air temperature, the correlation coefficient being 0.18. The relationship of the forest lightning fire with lightning was also related to temporal scales. At yearly scale, there was no significant correlation between them; at monthly scale, the forest lightning fire was strongly correlated with lightning and affected by precipitation; at daily scale, a positive correlation was observed between forest lightning fire and lightning when the precipitation was less than 5 mm. According to these findings, a fire danger index based on ADTD lightning detection data was established, and a forest lightning fire forecast model was developed. The prediction accuracy of this model for the forest lightning fire in Daxing' anling Mountains in 2005-2007 was > 80%.

A mobile test facility based on a magnetic cumulative generator to study the stability of the power plants under impact of lightning currents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shurupov, A. V.; Zavalova, V. E., E-mail: zavalova@fites.ru; Kozlov, A. V.

The report presents the results of the development and field testing of a mobile test facility based on a helical magnetic cumulative generator (MCGTF). The system is designed for full-scale modeling of lightning currents to study the safety of power plants of any type, including nuclear power plants. Advanced technologies of high-energy physics for solving both engineering and applied problems underlie this pilot project. The energy from the magnetic cumulative generator (MCG) is transferred to a high-impedance load with high efficiency of more than 50% using pulse transformer coupling. Modeling of the dynamics of the MEG that operates in amore » circuit with lumped parameters allows one to apply the law of inductance output during operation of the MCG, thus providing the required front of the current pulse in the load without using any switches. The results of field testing of the MCGTF are presented for both the ground loop and the model load. The ground loop generates a load resistance of 2–4 Ω. In the tests, the ohmic resistance of the model load is 10 Ω. It is shown that the current pulse parameters recorded in the resistive-inductive load are close to the calculated values.« less

Quantifying the Influence of Lightning Strike Pressure Loading on Composite Specimen Damage

NASA Astrophysics Data System (ADS)

Foster, P.; Abdelal, G.; Murphy, A.

2018-04-01

Experimental work has shown that a component of lightning strike damage is caused by a mechanical loading. As the profile of the pressure loading is unknown a number of authors propose different pressure loads, varying in form, application area and magnitude. The objective of this paper is to investigate the potential contribution of pressure loading to composite specimen damage. This is achieved through a simulation study using an established modelling approach for composite damage prediction. The study examines the proposed shockwave loads from the literature. The simulation results are compared with measured test specimen damage examining the form and scale of damage. The results for the first time quantify the significance of pressure loading, demonstrating that although a pressure load can cause damage consistent with that measured experimentally, it has a negligible contribution to the overall scale of damage. Moreover the requirements for a pressure to create the damage behaviours typically witnessed in testing requires that the pressure load be within a very precise window of magnitude and loading area.

The Reduction of NOx Using Pulsed Electron Beams

DTIC Science & Technology

2015-12-30

flue gas (SFG) is described. The SFG is a simulant for exhaust flue gas from a coal combustion power plant. The technology utilizes a pulsed electron...a surrogate flue gas (SFG) is described. The SFG simulates exhaust flue gas from a coal combustion power plant. The technology utilizes a pulsed...temperature combustion in air-breathing engines and coal power plants. The gases are also produced in nature during thunderstorms by lightning

Meteorological Support at the Savanna River Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Addis, Robert P.

2005-10-14

The Department of Energy (DOE) operates many nuclear facilities on large complexes across the United States in support of national defense. The operation of these many and varied facilities and processes require meteorological support for many purposes, including: for routine operations, to respond to severe weather events, such as lightning, tornadoes and hurricanes, to support the emergency response functions in the event of a release of materials to the environment, for engineering baseline and safety documentation, as well as hazards assessments etc. This paper describes a program of meteorological support to the Savannah River Site, a DOE complex located inmore » South Carolina.« less

The footprints of Saharan Air Layer and lightning on the formation of tropical depressions over the eastern Atlantic Ocean

NASA Astrophysics Data System (ADS)

Centeno Delgado, Diana C.

In this study, the results of an observational analysis and a numerical analysis on the role of the Saharan Air Layer during tropical cyclogenesis (TC-genesis) are described. The observational analysis investigates the interaction of dust particles and lightning during the genesis stage of two developed cases (Hurricanes Helene 2006 and Julia 2010). The Weather Research and Forecasting (WRF) and WRF-Chemistry models were used to include and monitor the aerosols and chemical processes that affect TC-genesis. The numerical modeling involved two developed cases (Hurricanes Helene 2006 and Julia 2010) and two non-developed cases (Non-Developed 2011 and Non-Developed 2012). The Aerosol Optical Depth (AOD) and lightning analysis for Hurricane Helene 2006 demonstrated the time-lag connection through their positive contribution to TC-genesis. The observational analyses supported the fact that both systems developed under either strong or weak dust conditions. From the two cases, the location of strong versus weak dust outbreaks in association with lightning was essential interactions that impacted TC-genesis. Furthermore, including dust particles, chemical processes, and aerosol feedback in the simulations with WRF-CHEM provides results closer to observations than regular WRF. The model advantageously shows the location of the dust particles inside of the tropical system. Overall, the results from this study suggest that the SAL is not a determining factor that affects the formation of tropical cyclones.

LOFAR Lightning Imaging: Mapping Lightning With Nanosecond Precision

NASA Astrophysics Data System (ADS)

Hare, B. M.; Scholten, O.; Bonardi, A.; Buitink, S.; Corstanje, A.; Ebert, U.; Falcke, H.; Hörandel, J. R.; Leijnse, H.; Mitra, P.; Mulrey, K.; Nelles, A.; Rachen, J. P.; Rossetto, L.; Rutjes, C.; Schellart, P.; Thoudam, S.; Trinh, T. N. G.; ter Veen, S.; Winchen, T.

2018-03-01

Lightning mapping technology has proven instrumental in understanding lightning. In this work we present a pipeline that can use lightning observed by the LOw-Frequency ARray (LOFAR) radio telescope to construct a 3-D map of the flash. We show that LOFAR has unparalleled precision, on the order of meters, even for lightning flashes that are over 20 km outside the area enclosed by LOFAR antennas (˜3,200 km2), and can potentially locate over 10,000 sources per lightning flash. We also show that LOFAR is the first lightning mapping system that is sensitive to the spatial structure of the electrical current during individual lightning leader steps.

Satellite Proving Ground for the GOES-R Geostationary Lightning Mapper (GLM)

NASA Technical Reports Server (NTRS)

Goodman, Steven J.; Gurka, James; Bruning, E. C.; Blakeslee, J. R.; Rabin, Robert; Buechler, D.

2009-01-01

The key mission of the Satellite Proving Ground is to demonstrate new satellite observing data, products and capabilities in the operational environment to be ready on Day 1 to use the GOES-R suite of measurements. Algorithms, tools, and techniques must be tested, validated, and assessed by end users for their utility before they are finalized and incorporated into forecast operations. The GOES-R Proving Ground for the Geostationary Lightning Mapper (GLM) focuses on evaluating how the infusion of the new technology, algorithms, decision aids, or tailored products integrate with other available tools (weather radar and ground strike networks; nowcasting systems, mesoscale analysis, and numerical weather prediction models) in the hands of the forecaster responsible for issuing forecasts and warning products. Additionally, the testing concept fosters operation and development staff interactions which will improve training materials and support documentation development. Real-time proxy total lightning data from regional VHF lightning mapping arrays (LMA) in Northern Alabama, Central Oklahoma, Cape Canaveral Florida, and the Washington, DC Greater Metropolitan Area are the cornerstone for the GLM Proving Ground. The proxy data will simulate the 8 km Event, Group and Flash data that will be generated by GLM. Tailored products such as total flash density at 1-2 minute intervals will be provided for display in AWIPS-2 to select NWS forecast offices and national centers such as the Storm Prediction Center. Additional temporal / spatial combinations are being investigated in coordination with operational needs and case-study proxy data and prototype visualizations may also be generated from the NASA heritage Lightning Imaging Sensor and Optical Transient Detector data. End users will provide feedback on the utility of products in their operational environment, identify use cases and spatial/temporal scales of interest, and provide feedback to the developers for adjusted or new products.

Image navigation and registration for the geostationary lightning mapper (GLM)

NASA Astrophysics Data System (ADS)

van Bezooijen, Roel W. H.; Demroff, Howard; Burton, Gregory; Chu, Donald; Yang, Shu S.

2016-10-01

The Geostationary Lightning Mappers (GLM) for the Geostationary Operational Environmental Satellite (GOES) GOES-R series will, for the first time, provide hemispherical lightning information 24 hours a day from longitudes of 75 and 137 degrees west. The first GLM of a series of four is planned for launch in November, 2016. Observation of lightning patterns by GLM holds promise to improve tornado warning lead times to greater than 20 minutes while halving the present false alarm rates. In addition, GLM will improve airline traffic flow management, and provide climatology data allowing us to understand the Earth's evolving climate. The paper describes the method used for translating the pixel position of a lightning event to its corresponding geodetic longitude and latitude, using the J2000 attitude of the GLM mount frame reported by the spacecraft, the position of the spacecraft, and the alignment of the GLM coordinate frame relative to its mount frame. Because the latter alignment will experience seasonal variation, this alignment is determined daily using GLM background images collected over the previous 7 days. The process involves identification of coastlines in the background images and determination of the alignment change necessary to match the detected coastline with the coastline predicted using the GSHHS database. Registration is achieved using a variation of the Lucas-Kanade algorithm where we added a dither and average technique to improve performance significantly. An innovative water mask technique was conceived to enable self-contained detection of clear coastline sections usable for registration. Extensive simulations using accurate visible images from GOES13 and GOES15 have been used to demonstrate the performance of the coastline registration method, the results of which are presented in the paper.

MicroCameras and Photometers (MCP) on board the TARANIS satellite

NASA Astrophysics Data System (ADS)

Farges, T.; Hébert, P.; Le Mer-Dachard, F.; Ravel, K.; Gaillac, S.

2017-12-01

TARANIS (Tool for the Analysis of Radiations from lightNing and Sprites) is a CNES micro satellite. Its main objective is to study impulsive transfers of energy between the Earth atmosphere and the space environment. It will be sun-synchronous at an altitude of 700 km. It will be launched in 2019 for at least 2 years. Its payload is composed of several electromagnetic instruments in different wavelengths (from gamma-rays to radio waves including optical). TARANIS instruments are currently in calibration and qualification phase. The purpose is to present the MicroCameras and Photometers (MCP) design, to show its performances after its recent characterization and at last to discuss the scientific objectives and how we want to answer it with the MCP observations. The MicroCameras, developed by Sodern, are dedicated to the spatial description of TLEs and their parent lightning. They are able to differentiate sprite and lightning thanks to two narrow bands ([757-767 nm] and [772-782 nm]) that provide simultaneous pairs of images of an Event. Simulation results of the differentiation method will be shown. After calibration and tests, the MicroCameras are now delivered to the CNES for integration on the payload. The Photometers, developed by Bertin Technologies, will provide temporal measurements and spectral characteristics of TLEs and lightning. There are key instrument because of their capability to detect on-board TLEs and then switch all the instruments of the scientific payload in their high resolution acquisition mode. Photometers use four spectral bands in the [170-260 nm], [332-342 nm], [757-767 nm] and [600-900 nm] and have the same field of view as cameras. The on-board TLE detection algorithm remote-controlled parameters have been tuned before launch using the electronic board and simulated or real events waveforms. After calibration, the Photometers are now going through the environmental tests. They will be delivered to the CNES for integration on the payload in September 2017.

[Neurological diseases after lightning strike : Lightning strikes twice].

PubMed

Gruhn, K M; Knossalla, Frauke; Schwenkreis, Peter; Hamsen, Uwe; Schildhauer, Thomas A; Tegenthoff, Martin; Sczesny-Kaiser, Matthias

2016-06-01

Lightning strikes rarely occur but 85 % of patients have lightning-related neurological complications. This report provides an overview about different modes of energy transfer and neurological conditions related to lightning strikes. Moreover, two case reports demonstrate the importance of interdisciplinary treatment and the spectrum of neurological complications after lightning strikes.

The NASA Lightning Nitrogen Oxides Model (LNOM): Recent Updates and Applications

NASA Technical Reports Server (NTRS)

Koshak, William; Peterson, Harold; Biazar, Arastoo; Khan, Maudood; Wang, Lihua; Park, Yee-Hun

2011-01-01

Improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are presented. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network(tm) (NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NOx (= NO + NO2). Lightning channel length distributions and lightning 10-m segment altitude distributions are also provided. In addition to NOx production from lightning return strokes, the LNOM now includes non-return stroke lightning NOx production due to: hot core stepped and dart leaders, stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NOx for an August 2006 run of CMAQ is discussed.

Visual Analytics approach for Lightning data analysis and cell nowcasting

NASA Astrophysics Data System (ADS)

Peters, Stefan; Meng, Liqiu; Betz, Hans-Dieter

2013-04-01

Thunderstorms and their ground effects, such as flash floods, hail, lightning, strong wind and tornadoes, are responsible for most weather damages (Bonelli & Marcacci 2008). Thus to understand, identify, track and predict lightning cells is essential. An important aspect for decision makers is an appropriate visualization of weather analysis results including the representation of dynamic lightning cells. This work focuses on the visual analysis of lightning data and lightning cell nowcasting which aim to detect and understanding spatial-temporal patterns of moving thunderstorms. Lightnings are described by 3D coordinates and the exact occurrence time of lightnings. The three-dimensionally resolved total lightning data used in our experiment are provided by the European lightning detection network LINET (Betz et al. 2009). In all previous works, lightning point data, detected lightning cells and derived cell tracks are visualized in 2D. Lightning cells are either displayed as 2D convex hulls with or without the underlying lightning point data. Due to recent improvements of lightning data detection and accuracy, there is a growing demand on multidimensional and interactive visualization in particular for decision makers. In a first step lightning cells are identified and tracked. Then an interactive graphic user interface (GUI) is developed to investigate the dynamics of the lightning cells: e.g. changes of cell density, location, extension as well as merging and splitting behavior in 3D over time. In particular a space time cube approach is highlighted along with statistical analysis. Furthermore a lightning cell nowcasting is conducted and visualized. The idea thereby is to predict the following cell features for the next 10-60 minutes including location, centre, extension, density, area, volume, lifetime and cell feature probabilities. The main focus will be set to a suitable interactive visualization of the predicted featured within the GUI. The developed visual exploring tool for the purpose of supporting decision making is investigated for two determined user groups: lightning experts and interested lay public. Betz HD, Schmidt K, Oettinger WP (2009) LINET - An International VLF/LF Lightning Detection Network in Europe. In: Betz HD, Schumann U, Laroche P (eds) Lightning: Principles, Instruments and Applications. Springer Netherlands, Dordrecht, pp 115-140 Bonelli P, Marcacci P (2008) Thunderstorm nowcasting by means of lightning and radar data: algorithms and applications in northern Italy. Nat. Hazards Earth Syst. Sci 8(5):1187-1198

Global Lightning Activity

NASA Technical Reports Server (NTRS)

Christian, Hugh J.

2004-01-01

Our knowledge of the global distribution of lightning has improved dramatically since the advent of spacebased lightning observations. Of major importance was the 1995 launch of the Optical Transient Detector (OTD), followed in 1997 by the launch of the Lightning Imaging Sensor (LIS). Together, these instruments have generated a continuous eight-year record of global lightning activity. These lightning observations have provided a new global perspective on total lightning activity. For the first time, total lightning activity (cloud-to-ground and intra-cloud) has been observed over large regions with high detection efficiency and accurate geographic location. This has produced new insights into lightning distributions, times of occurrence and variability. It has produced a revised global flash rate estimate (44 flashes per second) and has lead to a new realization of the significance of total lightning activity in severe weather. Accurate flash rate estimates are now available over large areas of the earth (+/- 72 deg. latitude). Ocean-land contrasts as a function of season are clearly reveled, as are orographic effects and seasonal and interannual variability. The space-based observations indicate that air mass thunderstorms, not large storm system dominate global activity. The ability of LIS and OTD to detect total lightning has lead to improved insight into the correlation between lightning and storm development. The relationship between updraft development and lightning activity is now well established and presents an opportunity for providing a new mechanism for remotely monitoring storm development. In this concept, lightning would serve as a surrogate for updraft velocity. It is anticipated that this capability could lead to significantly improved severe weather warning times and reduced false warning rates. This talk will summarize our space-based lightning measurements, will discuss how lightning observations can be used to monitor severe weather, and present a concept for continuous geostationary-based lightning observations.

Number of lightning discharges causing damage to lightning arrester cables for aerial transmission lines in power systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikiforov, E. P.

2009-07-15

Damage by lightning discharges to lightning arrester cables for 110-175 kV aerial transmission lines is analyzed using data from power systems on incidents with aerial transmission lines over a ten year operating period (1997-2006). It is found that failures of lightning arrester cables occur when a tensile force acts on a cable heated to the melting point by a lightning current. The lightning currents required to heat a cable to this extent are greater for larger cable cross sections. The probability that a lightning discharge will develop decreases as the amplitude of the lightning current increases, which greatly reduces themore » number of lightning discharges which damage TK-70 cables compared to TK-50 cables. In order to increase the reliability of lightning arrester cables for 110 kV aerial transmission lines, TK-70 cables should be used in place of TK-50 cables. The number of lightning discharges per year which damage lightning arrester cables is lowered when the density of aerial transmission lines is reduced within the territory of electrical power systems. An approximate relationship between these two parameters is obtained.« less

Characteristics of the Lightning Activities in Southwest China from Low-Earth Orbiting and Geostationary Satellites-, and Ground-based Lightning Observations

NASA Astrophysics Data System (ADS)

Hui, W.; Huang, F.; Guo, Q.; Li, D.; Yao, Z.; Zou, W.

2017-12-01

The development of lightning detection technology accumulates a large amount of long-term data for investigating the lightning activities. Ground-based lightning networks provide continuous lightning location but offer limited spatial coverage because of the complex underlying surface conditions. Space-based optical sensors can detect lightning with global homogeneity. However, observing from satellites in low-earth orbit has fixed locations at the ground very shortly during its overpasses. The latest launched geostationary satellite-based lightning imagers can detect lightning in real time, and provide complete life-cycle coverage of each observed thunderstorm. In this study, based on multi-source lightning data, the lightning activities in southwest China, which with complex terrain and prone to appear lightning, are researched. Firstly, the climatological characteristics of lightning activities in this region from 1998 to 2013 are analyzed by using very-high resolution (0.1°) Lightning Imaging Sensor (LIS)-derived data. The results indicate that the lightning activity is more intense in eastern and southern regions of southwest China than in western and northern regions; the monthly and hourly flash densities also show its obvious seasonal and diurnal variation respectively, which is consistent with the development of the convective systems in the region. The results show that the spatial and temporal distribution of lightning activities in southwest China is related to its topography, water vapor, and atmospheric conditions. Meanwhile, by comparing with the analysis derived data from Chinese Ground-based Lightning Location System, the LIS-based detection results are confirmed. Furthermore, the process of a thunderstorm in southwest China from 29 to 30 March 2017 is investigated by using the new-generation monitoring data of Chinese Fengyun-4 geostationary satellite-based Lightning Mapping Imager (LMI) and the rainfall data. The results tell us more about the behavior of lightning while the thunderstorm traverses through the region, and also demonstrate the correlation between the rainfall amounts and the storm track. This study will contribute to applications of lightning data to improve monitoring and forecasting of severe weather.

Severe weather detection by using Japanese Total Lightning Network

NASA Astrophysics Data System (ADS)

Hobara, Yasuhide; Ishii, Hayato; Kumagai, Yuri; Liu, Charlie; Heckman, Stan; Price, Colin

2015-04-01

In this paper we demonstrate the preliminary results from the first Japanese Total Lightning Network. The University of Electro-Communications (UEC) recently deployed Earth Networks Total Lightning System over Japan to conduct various lightning research projects. Here we analyzed the total lightning data in relation with 10 severe events such as gust fronts and tornadoes occurred in 2014 in mainland Japan. For the analysis of these events, lightning jump algorithm was used to identify the increase of the flash rate in prior to the severe weather events. We found that lightning jumps associated with significant increasing lightning activities for total lightning and IC clearly indicate the severe weather occurrence than those for CGs.

A Lightning Channel Retrieval Algorithm for the North Alabama Lightning Mapping Array (LMA)

NASA Technical Reports Server (NTRS)

Koshak, William; Arnold, James E. (Technical Monitor)

2002-01-01

A new multi-station VHF time-of-arrival (TOA) antenna network is, at the time of this writing, coming on-line in Northern Alabama. The network, called the Lightning Mapping Array (LMA), employs GPS timing and detects VHF radiation from discrete segments (effectively point emitters) that comprise the channel of lightning strokes within cloud and ground flashes. The network will support on-going ground validation activities of the low Earth orbiting Lightning Imaging Sensor (LIS) satellite developed at NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama. It will also provide for many interesting and detailed studies of the distribution and evolution of thunderstorms and lightning in the Tennessee Valley, and will offer many interesting comparisons with other meteorological/geophysical wets associated with lightning and thunderstorms. In order to take full advantage of these benefits, it is essential that the LMA channel mapping accuracy (in both space and time) be fully characterized and optimized. In this study, a new revised channel mapping retrieval algorithm is introduced. The algorithm is an extension of earlier work provided in Koshak and Solakiewicz (1996) in the analysis of the NASA Kennedy Space Center (KSC) Lightning Detection and Ranging (LDAR) system. As in the 1996 study, direct algebraic solutions are obtained by inverting a simple linear system of equations, thereby making computer searches through a multi-dimensional parameter domain of a Chi-Squared function unnecessary. However, the new algorithm is developed completely in spherical Earth-centered coordinates (longitude, latitude, altitude), rather than in the (x, y, z) cartesian coordinates employed in the 1996 study. Hence, no mathematical transformations from (x, y, z) into spherical coordinates are required (such transformations involve more numerical error propagation, more computer program coding, and slightly more CPU computing time). The new algorithm also has a more realistic definition of source altitude that accounts for Earth oblateness (this can become important for sources that are hundreds of kilometers away from the network). In addition, the new algorithm is being applied to analyze computer simulated LMA datasets in order to obtain detailed location/time retrieval error maps for sources in and around the LMA network. These maps will provide a more comprehensive analysis of retrieval errors for LMA than the 1996 study did of LDAR retrieval errors. Finally, we note that the new algorithm can be applied to LDAR, and essentially any other multi-station TWA network that depends on direct line-of-site antenna excitation.

Tortuosity of lightning return stroke channels

NASA Technical Reports Server (NTRS)

Levine, D. M.; Gilson, B.

1984-01-01

Data obtained from photographs of lightning are presented on the tortuosity of return stroke channels. The data were obtained by making piecewise linear fits to the channels, and recording the cartesian coordinates of the ends of each linear segment. The mean change between ends of the segments was nearly zero in the horizontal direction and was about eight meters in the vertical direction. Histograms of these changes are presented. These data were used to create model lightning channels and to predict the electric fields radiated during return strokes. This was done using a computer generated random walk in which linear segments were placed end-to-end to form a piecewise linear representation of the channel. The computer selected random numbers for the ends of the segments assuming a normal distribution with the measured statistics. Once the channels were simulated, the electric fields radiated during a return stroke were predicted using a transmission line model on each segment. It was found that realistic channels are obtained with this procedure, but only if the model includes two scales of tortuosity: fine scale irregularities corresponding to the local channel tortuosity which are superimposed on large scale horizontal drifts. The two scales of tortuosity are also necessary to obtain agreement between the electric fields computed mathematically from the simulated channels and the electric fields radiated from real return strokes. Without large scale drifts, the computed electric fields do not have the undulations characteristics of the data.

Total Lightning as an Indicator of Mesocyclone Behavior

NASA Technical Reports Server (NTRS)

Stough, Sarah M.; Carey, Lawrence D.; Schultz, Christopher J.

2014-01-01

Apparent relationship between total lightning (in-cloud and cloud to ground) and severe weather suggests its operational utility. Goal of fusion of total lightning with proven tools (i.e., radar lightning algorithms. Preliminary work here investigates circulation from Weather Suveilance Radar- 1988 Doppler (WSR-88D) coupled with total lightning data from Lightning Mapping Arrays.

Nowcasting and forecasting of lightning activity: the Talos project.

NASA Astrophysics Data System (ADS)

Lagouvardos, Kostas; Kotroni, Vassiliki; Kazadzis, Stelios; Giannaros, Theodore; Karagiannidis, Athanassios; Galanaki, Elissavet; Proestakis, Emmanouil

2015-04-01

Thunder And Lightning Observing System (TALOS) is a research program funded by the Greek Ministry of Education with the aim to promote excellence in the field of lightning meteorology. The study focuses on exploring the real-time observations provided by the ZEUS lightning detection system, operated by the National Observatory of Athens since 2005, as well as the 10-year long database of the same system. More precisely the main research issues explored are: - lightning climatology over the Mediterranean focusing on lightning spatial and temporal distribution, on the relation of lightning with topographical features and instability and on the importance of aerosols in lightning initiation and enhancement. - nowcasting of lightning activity over Greece, with emphasis on the operational aspects of this endeavour. The nowcasting tool is based on the use of lightning data complemented by high-time resolution METEOSAT imagery. - forecasting of lightning activity over Greece based on the use of WRF numerical weather prediction model. - assimilation of lightning with the aim to improve the model precipitation forecast skill. In the frame of this presentation the main findings of each of the aforementioned issues are highlighted.

Estimates of the Lightning NOx Profile in the Vicinity of the North Alabama Lightning Mapping Array

NASA Technical Reports Server (NTRS)

Koshak, William J.; Peterson, Harold S.; McCaul, Eugene W.; Blazar, Arastoo

2010-01-01

The NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) is applied to August 2006 North Alabama Lightning Mapping Array (NALMA) data to estimate the (unmixed and otherwise environmentally unmodified) vertical source profile of lightning nitrogen oxides, NOx = NO + NO2. Data from the National Lightning Detection Network (Trademark) (NLDN) is also employed. This is part of a larger effort aimed at building a more realistic lightning NOx emissions inventory for use by the U.S. Environmental Protection Agency (EPA) Community Multiscale Air Quality (CMAQ) modeling system. Overall, special attention is given to several important lightning variables including: the frequency and geographical distribution of lightning in the vicinity of the NALMA network, lightning type (ground or cloud flash), lightning channel length, channel altitude, channel peak current, and the number of strokes per flash. Laboratory spark chamber results from the literature are used to convert 1-meter channel segments (that are located at a particular known altitude; i.e., air density) to NOx concentration. The resulting lightning NOx source profiles are discussed.

Lightning Safety Tips and Resources

MedlinePlus

... Safety Brochure U.S. Lightning Deaths in 2018 : 5 Youtube: Lightning Safety for the Deaf and Hard of ... for Hard of Hearing: jpg , high res png YouTube: Lightning Safety Tips Lightning Safety When Working Outdoors : ...

Where are the lightning hotspots on Earth?

NASA Astrophysics Data System (ADS)

Albrecht, R. I.; Goodman, S. J.; Buechler, D. E.; Blakeslee, R. J.; Christian, H. J., Jr.

2015-12-01

The first lightning observations from space date from the early 1960s and more than a dozen spacecraft orbiting the Earth have flown instruments that recorded lightning signals from thunderstorms over the past 45 years. In this respect, the Tropical Rainfall Measuring Mission (TRMM) Lightning Imaging Sensor (LIS), having just completed its mission (1997-2015), provides the longest and best total (intracloud and cloud-to-ground) lightning data base over the tropics.We present a 16 year (1998-2013) reprocessed data set to create very high resolution (0.1°) TRMM LIS total lightning climatology. This detailed very high resolution climatology is used to identify the Earth's lightning hotspots and other regional features. Earlier studies located the lightning hotspot within the Congo Basin in Africa, but our very high resolution lightning climatology found that the highest lightning flash rate on Earth actually occurs in Venezuela over Lake Maracaibo, with a distinct maximum during the night. The higher resolution dataset clearly shows that similar phenomenon also occurs over other inland lakes with similar conditions, i.e., locally forced convergent flow over a warm lake surface which drives deep nocturnal convection. Although Africa does not have the top lightning hotspot, it comes in a close second and it is the continent with the highest number of lightning hotspots, followed by Asia, South America, North America, and Oceania. We also present climatological maps for local hour and month of lightning maxima, along with a ranking of the highest five hundred lightning maxima, focusing discussion on each continent's 10 highest lightning maxima. Most of the highest continental maxima are located near major mountain ranges, revealing the importance of local topography in thunderstorm development. These results are especially relevant in anticipation of the upcoming availability of continuous total lightning observations from the Geostationary Lightning Mapping (GLM) aboard GOES-R. This study provides context to forecasters as to total lightning activity and locations within GLM field of view as well as around the world.

NASA Manned Launch Vehicle Lightning Protection Development

NASA Technical Reports Server (NTRS)

McCollum, Matthew B.; Jones, Steven R.; Mack, Jonathan D.

2009-01-01

Historically, the National Aeronautics and Space Administration (NASA) relied heavily on lightning avoidance to protect launch vehicles and crew from lightning effects. As NASA transitions from the Space Shuttle to the new Constellation family of launch vehicles and spacecraft, NASA engineers are imposing design and construction standards on the spacecraft and launch vehicles to withstand both the direct and indirect effects of lightning. A review of current Space Shuttle lightning constraints and protection methodology will be presented, as well as a historical review of Space Shuttle lightning requirements and design. The Space Shuttle lightning requirements document, NSTS 07636, Lightning Protection, Test and Analysis Requirements, (originally published as document number JSC 07636, Lightning Protection Criteria Document) was developed in response to the Apollo 12 lightning event and other experiences with NASA and the Department of Defense launch vehicles. This document defined the lightning environment, vehicle protection requirements, and design guidelines for meeting the requirements. The criteria developed in JSC 07636 were a precursor to the Society of Automotive Engineers (SAE) lightning standards. These SAE standards, along with Radio Technical Commission for Aeronautics (RTCA) DO-160, Environmental Conditions and Test Procedures for Airborne Equipment, are the basis for the current Constellation lightning design requirements. The development and derivation of these requirements will be presented. As budget and schedule constraints hampered lightning protection design and verification efforts, the Space Shuttle elements waived the design requirements and relied on lightning avoidance in the form of launch commit criteria (LCC) constraints and a catenary wire system for lightning protection at the launch pads. A better understanding of the lightning environment has highlighted the vulnerability of the protection schemes and associated risk to the vehicle, which has resulted in lost launch opportunities and increased expenditures in manpower to assess Space Shuttle vehicle health and safety after lightning events at the launch pad. Because of high-percentage launch availability and long-term on-pad requirements, LCC constraints are no longer considered feasible. The Constellation vehicles must be designed to withstand direct and indirect effects of lightning. A review of the vehicle design and potential concerns will be presented as well as the new catenary lightning protection system for the launch pad. This system is required to protect the Constellation vehicles during launch processing when vehicle lightning effects protection might be compromised by such items as umbilical connections and open access hatches.

The electric field changes and UHF radiations caused by the triggered lightning in Japan

NASA Technical Reports Server (NTRS)

Kawasaki, Zen-Ichiro; Kanao, Tadashi; Matsuura, Kenji; Nakano, Minoru; Horii, Kenji; Nakamura, Koichi

1991-01-01

In the rocket triggered lightning experiment of fiscal 1989, researchers observed electromagnetic field changes and UHF electromagnetic radiation accompanying rocket triggered lightning. It was found that no rapid changes corresponding to the return stroke of natural lightning were observed in the electric field changes accompanying rocket triggered lightning. However, continuous currents were present. In the case of rocket triggered lightning to the tower, electromagnetic field changes corresponding to the initiation of triggered lightning showed a bipolar pulse of a relatively large amplitude. In contrast, the rocket triggered lightning to the ground did not have such a bipolar pulse. The UHF radiation accompanying the rocket triggered lightning preceded the waveform portions corresponding to the first changes in electromagnetic fields. The number of isolated pulses in the UHF radiation showed a correlation with the time duration from rocket launching up to triggered lightning. The time interval between consecutive isolated pulses tended to get shorter with the passage of time, just like the stepped leaders of natural lightning.

Cross-Referencing GLM and ISS-LIS with Ground-Based Lightning Networks

NASA Astrophysics Data System (ADS)

Virts, K.; Blakeslee, R. J.; Goodman, S. J.; Koshak, W. J.

2017-12-01

The Geostationary Lightning Mapper (GLM), in geostationary orbit aboard GOES-16 since late 2016, and the Lightning Imaging Sensor (LIS), installed on the International Space Station in February 2017, provide observations of total lightning activity from space. ISS-LIS samples the global tropics and mid-latitudes, while GLM observes the full thunderstorm life-cycle over the Americas and surrounding oceans. The launch of these instruments provides an unprecedented opportunity to compare lightning observations across multiple space-based optical lightning sensors. In this study, months of observations from GLM and ISS-LIS are cross-referenced with each other and with lightning detected by the ground-based Earth Networks Global Lightning Network (ENGLN) and the Vaisala Global Lightning Dataset 360 (GLD360) throughout and beyond the GLM field-of-view. In addition to calibration/validation of the new satellite sensors, this study provides a statistical comparison of the characteristics of lightning observed by the satellite and ground-based instruments, with an emphasis on the lightning flashes uniquely identified by the satellites.

Lightning-Related Indicators for National Climate Assessment (NCA) Studies

NASA Astrophysics Data System (ADS)

Koshak, W. J.

2017-12-01

With the recent advent of space-based lightning mappers [i.e., the Geostationary Lightning Mapper (GLM) on GOES-16, and the Lightning Imaging Sensor (LIS) on the International Space Station], improved investigations on the inter-relationships between lightning and climate are now possible and can directly support the goals of the National Climate Assessment (NCA) program. Lightning nitrogen oxides (LNOx) affect greenhouse gas concentrations such as ozone that influences changes in climate. Conversely, changes in climate (from any causes) can affect the characteristics of lightning (e.g., frequency, current amplitudes, multiplicity, polarity) that in turn leads to changes in lightning-caused impacts to humans (e.g., fatalities, injuries, crop/property damage, wildfires, airport delays, changes in air quality). This study discusses improvements to, and recent results from, the NASA/MSFC NCA Lightning Analysis Tool (LAT). It includes key findings on the development of different types of lightning flash energy indicators derived from space-based lightning observations, and demonstrates how these indicators can be used to estimate trends in LNOx across the continental US.

An In Depth Look at Lightning Trends in Hurricane Harvey using Satellite and Ground-Based Measurements

NASA Astrophysics Data System (ADS)

Ringhausen, J.

2017-12-01

This research combines satellite measurements of lightning in Hurricane Harvey with ground-based lightning measurements to get a better sense of the total lightning occurring in the hurricane, both intra-cloud (IC) and cloud-to-ground (CG), and how it relates to the intensification and weakening of the tropical system. Past studies have looked at lightning trends in hurricanes using the space based Lightning Imaging Sensor (LIS) or ground-based lightning detection networks. However, both of these methods have drawbacks. For instance, LIS was in low earth orbit, which limited lightning observations to 90 seconds for a particular point on the ground; hence, continuous lightning coverage of a hurricane was not possible. Ground-based networks can have a decreased detection efficiency, particularly for ICs, over oceans where hurricanes generally intensify. With the launch of the Geostationary Lightning Mapper (GLM) on the GOES-16 satellite, researchers can study total lightning continuously over the lifetime of a tropical cyclone. This study utilizes GLM to investigate total lightning activity in Hurricane Harvey temporally; this is augmented with spatial analysis relative to hurricane structure, similar to previous studies. Further, GLM and ground-based network data are combined using Bayesian techniques in a new manner to leverage the strengths of each detection method. This methodology 1) provides a more complete estimate of lightning activity and 2) enables the derivation of the IC:CG ratio (Z-ratio) throughout the time period of the study. In particular, details of the evolution of the Z-ratio in time and space are presented. In addition, lightning stroke spatiotemporal trends are compared to lightning flash trends. This research represents a new application of lightning data that can be used in future study of tropical cyclone intensification and weakening.

The NASA Lightning Nitrogen Oxides Model (LNOM): Application to Air Quality Modeling

NASA Technical Reports Server (NTRS)

Koshak, William; Peterson, Harold; Khan, Maudood; Biazar, Arastoo; Wang, Lihua

2011-01-01

Recent improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are discussed. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network(TradeMark)(NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NO(x) (= NO + NO2). The latest LNOM estimates of lightning channel length distributions, lightning 1-m segment altitude distributions, and the vertical profile of lightning NO(x) are presented. The primary improvement to the LNOM is the inclusion of non-return stroke lightning NOx production due to: (1) hot core stepped and dart leaders, (2) stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NO(x) for an August 2006 run of CMAQ is discussed.

KSC-2014-3532

NASA Image and Video Library

2014-08-14

CAPE CANAVERAL, Fla. – The lightning suppression system on Launch Pad 39B soon may be put to the test by a thunderstorm moving through the launch complex at NASA’s Kennedy Space Center in Florida. Kennedy's Ground Support Development and Operations Program is hard at work transforming the center's facilities into a multi-user spaceport, when the weather permits. For more on Kennedy Space Center, visit http://www.nasa.gov/kennedy. Photo credit: NASA/Ben Smegelsky

National Athletic Trainers' Association position statement: lightning safety for athletics and recreation.

PubMed

Walsh, Katie M; Cooper, Mary Ann; Holle, Ron; Rakov, Vladimir A; Roeder, William P; Ryan, Michael

2013-01-01

To present recommendations for the education, prevention, and management of lightning injuries for those involved in athletics or recreation. Lightning is the most common severe-storm activity encountered annually in the United States. The majority of lightning injuries can be prevented through an aggressive educational campaign, vacating outdoor activities before the lightning threat, and an understanding of the attributes of a safe place from the hazard. This position statement is focused on supplying information specific to lightning safety and prevention and treatment of lightning injury and providing lightning-safety recommendations for the certified athletic trainer and those who are involved in athletics and recreation.

The Lightning Nitrogen Oxides Model (LNOM): Status and Recent Applications

NASA Technical Reports Server (NTRS)

Koshak, William; Khan, Maudood; Peterson, Harold

2011-01-01

Improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) are discussed. Recent results from an August 2006 run of the Community Multiscale Air Quality (CMAQ) modeling system that employs LNOM lightning NOx (= NO + NO2) estimates are provided. The LNOM analyzes Lightning Mapping Array (LMA) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NOx. The latest LNOM estimates of (a) lightning channel length distributions, (b) lightning 1-m segment altitude distributions, and (c) the vertical profile of NOx are presented. The impact of including LNOM-estimates of lightning NOx on CMAQ output is discussed.

An Integrated 0-1 Hour First-Flash Lightning Nowcasting, Lightning Amount and Lightning Jump Warning Capability

NASA Technical Reports Server (NTRS)

Mecikalski, John; Jewett, Chris; Carey, Larry; Zavodsky, Brad; Stano, Geoffrey; Chronis, Themis

2015-01-01

Using satellite-based methods that provide accurate 0-1 hour convective initiation (CI) nowcasts, and rely on proven success coupling satellite and radar fields in the Corridor Integrated Weather System (CIWS; operated and developed at MIT-Lincoln Laboratory), to subsequently monitor for first-flash lightning initiation (LI) and later period lightning trends as storms evolve. Enhance IR-based methods within the GOES-R CI Algorithm (that must meet specific thresholds for a given cumulus cloud before the cloud is considered to have an increased likelihood of producing lightning next 90 min) that forecast LI. Integrate GOES-R CI and LI fields with radar thresholds (e.g., first greater than or equal to 40 dBZ echo at the -10 C altitude) and NWP model data within the WDSS-II system for LI-events from new convective storms. Track ongoing lightning using Lightning Mapping Array (LMA) and pseudo-Geostationary Lightning Mapper (GLM) data to assess per-storm lightning trends (e.g., as tied to lightning jumps) and outline threat regions. Evaluate the ability to produce LI nowcasts through a "lightning threat" product, and obtain feedback from National Weather Service forecasters on its value as a decision support tool.

Design analysis and computer-aided performance evaluation of shuttle orbiter electrical power system. Volume 1: Summary

NASA Technical Reports Server (NTRS)

1974-01-01

Studies were conducted to develop appropriate space shuttle electrical power distribution and control (EPDC) subsystem simulation models and to apply the computer simulations to systems analysis of the EPDC. A previously developed software program (SYSTID) was adapted for this purpose. The following objectives were attained: (1) significant enhancement of the SYSTID time domain simulation software, (2) generation of functionally useful shuttle EPDC element models, and (3) illustrative simulation results in the analysis of EPDC performance, under the conditions of fault, current pulse injection due to lightning, and circuit protection sizing and reaction times.

STS-4 test mission simulates operational flight: President terms success golden spike in space

NASA Technical Reports Server (NTRS)

1982-01-01

The fourth Space Shuttle flight is summarized. STS certification as operational, applications experiments, experiments involving crew, the first Getaway Special, a lightning survey. Shuttle environment measurement, prelaunch rain and hail, loss of solid rocket boosters, and modification of the thermal test program are reviewed.

Simulations of Tropospheric NO2 by the Global Modeling Initiative (GMI) Model Utilizing Assimilated and Forecast Meteorological Fields: Comparison to Ozone Monitoring Instrument (OMI) Measurements

NASA Technical Reports Server (NTRS)

Rodriquez, J. M.; Yoshida, Y.; Duncan, B. N.; Bucsela, E. J.; Gleason, J. F.; Allen, D.; Pickering, K. E.

2007-01-01

We present simulations of the tropospheric composition for the years 2004 and 2005, carried out by the GMI Combined Stratosphere-Troposphere (Combo) model, at a resolution of 2degx2.5deg. The model includes a new parameterization of lightning sources of NO(x) which is coupled to the cloud mass fluxes in the adopted meteorological fields. These simulations use two different sets of input meteorological fields: a)late-look assimilated fields from the Global Modeling and Assimilation Office (GMAO), GEOS-4 system and b) 12-hour forecast fields initialized with the assimilated data. Comparison of the forecast to the assimilated fields indicates that the forecast fields exhibit less vigorous convection, and yield tropical precipitation fields in better agreement with observations. Since these simulations include a complete representation of the stratosphere, they provide realistic stratosphere-tropospheric fluxes of O3 and NO(y). Furthermore, the stratospheric contribution to total columns of different troposheric species can be subtracted in a consistent fashion, and the lightning production of NO(y) will depend on the adopted meteorological field. We concentrate here on the simulated tropospheric columns of NO2, and compare them to observations by the OM1 instrument for the years 2004 and 2005. The comparison is used to address these questions: a) is there a significant difference in the agreement/disagreement between simulations for these two different meteorological fields, and if so, what causes these differences?; b) how do the simulations compare to OMI observations, and does this comparison indicate an improvement in simulations with the forecast fields? c) what are the implications of these simulations for our understanding of the NO2 emissions over continental polluted regions?

Estimates of the Lightning NOx Profile in the Vicinity of the North Alabama Lightning Mapping Array

NASA Technical Reports Server (NTRS)

Koshak, William J.; Peterson, Harold

2010-01-01

The NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) is applied to August 2006 North Alabama Lightning Mapping Array (LMA) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning nitrogen oxides, NOx = NO + NO 2 . This is part of a larger effort aimed at building a more realistic lightning NOx emissions inventory for use by the U.S. Environmental Protection Agency (EPA) Community Multiscale Air Quality (CMAQ) modeling system. Data from the National Lightning Detection Network TM (NLDN) is also employed. Overall, special attention is given to several important lightning variables including: the frequency and geographical distribution of lightning in the vicinity of the LMA network, lightning type (ground or cloud flash), lightning channel length, channel altitude, channel peak current, and the number of strokes per flash. Laboratory spark chamber results from the literature are used to convert 1-meter channel segments (that are located at a particular known altitude; i.e., air density) to NOx concentration. The resulting raw NOx profiles are discussed.

Optimizing Precipitation Thresholds for Best Correlation Between Dry Lightning and Wildfires

NASA Astrophysics Data System (ADS)

Vant-Hull, Brian; Thompson, Tollisha; Koshak, William

2018-03-01

This work examines how to adjust the definition of "dry lightning" in order to optimize the correlation between dry lightning flash count and the climatology of large (>400 km2) lightning-ignited wildfires over the contiguous United States (CONUS). The National Lightning Detection Network™ and National Centers for Environmental Prediction Stage IV radar-based, gauge-adjusted precipitation data are used to form climatic data sets. For a 13 year analysis period over CONUS, a correlation of 0.88 is found between annual totals of wildfires and dry lightning. This optimal correlation is found by defining dry lightning as follows: on a 0.1° hourly grid, a precipitation threshold of no more than 0.3 mm may accumulate during any hour over a period of 3-4 days preceding the flash. Regional optimized definitions vary. When annual totals are analyzed as done here, no clear advantage is found by weighting positive polarity cloud-to-ground (+CG) lightning differently than -CG lightning. The high variability of dry lightning relative to the precipitation and lightning from which it is derived suggests it would be an independent and useful climate indicator.

Lightning attachment process to common buildings

NASA Astrophysics Data System (ADS)

Saba, M. M. F.; Paiva, A. R.; Schumann, C.; Ferro, M. A. S.; Naccarato, K. P.; Silva, J. C. O.; Siqueira, F. V. C.; Custódio, D. M.

2017-05-01

The physical mechanism of lightning attachment to grounded structures is one of the most important issues in lightning physics research, and it is the basis for the design of the lightning protection systems. Most of what is known about the attachment process comes from leader propagation models that are mostly based on laboratory observations of long electrical discharges or from observations of lightning attachment to tall structures. In this paper we use high-speed videos to analyze the attachment process of downward lightning flashes to an ordinary residential building. For the first time, we present characteristics of the attachment process to common structures that are present in almost every city (in this case, two buildings under 60 m in São Paulo City, Brazil). Parameters like striking distance and connecting leaders speed, largely used in lightning attachment models and in lightning protection standards, are revealed in this work.