E Philip Krider - Academia.edu (original) (raw)

Papers by E Philip Krider

The public reporting burden for this collection of information is estimated to average 1 hour per... more The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to the Department of Defense. Executive Services and Communications Directorate (0704-0188). Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMP control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY)

Journal of Geophysical Research, 1989

A computer algorithm has been developed to derive accurate values of lightning‐caused changes in ... more A computer algorithm has been developed to derive accurate values of lightning‐caused changes in cloud electric fields under active storm conditions. This algorithm has been applied to data obtained from a network of ground‐based electric field mills at the NASA Kennedy Space Center and the U.S. Air Force Cape Canaveral Air Force Station during portions of two storms. The resulting field changes have been analyzed using a least squares optimization procedure and point‐charge (Q) and point‐dipole (P) models. The results indicate that the values and time variations of the Q‐model parameters under active storm conditions are similar to those reported previously for small storms (Maier and Krider, 1986) when the computations are done with the same analysis criteria and comparable biases. The parameters of P solutions seem to vary with time within the storm interval and from storm to storm. The P vectors at low altitudes all tend to point upward, and those at high altitudes almost always point downward. When a P solution is located in the altitude range corresponding to Q altitudes, the direction of P tends to be horizontal. Since Q solutions typically describe cloud‐to‐ground lightning and P solutions describe cloud discharges (Maier and Krider, 1986), the altitude dependence of the P vectors is consistent with the classic thundercloud charge model that has an excess negative charge at altitudes corresponding to the Q altitudes.

Natural and triggered lightning is a demonstrated hazard to the launch of space vehicles, and the... more Natural and triggered lightning is a demonstrated hazard to the launch of space vehicles, and the American space program has responded by establishing the "Lightning Flight Commit Criteria (LFCC)" to mitigate the risk. These LFCC are a complex set of rules with associated Definitions which must be satisfied before the launch of a space vehicle is permitted. The Definitions are an integral part of the LFCC; and the term LFCC, as used in this document, is explicitly intended to include those Definitions. Under the name Lightning launch Commit Criteria (LLCC) they apply to all Federal Government ranges including not only the well-known Eastern Range at Cape Canaveral, Florida, and the Western Range at Vandenberg AFB, California, but also smaller ranges such as the NASA range at Wallops Island, Virginia, the Air Force range at Kwajalein Atoll in the Pacific Ocean, and others. A slightly earlier version of these rules currently applies to all spaceports operating under the jurisdiction of the Federal Aviation Administration (14 CFR 417), and the FAA is expected to adopt the current version. The LFCC are developed and approved through a complex process, but the core science and recommendations for precise wording of the operative parts of the rules are provided by a "Lightning Advisory Panel (LAP)" consisting of American scientists working in atmospheric electricity and related disciplines including cloud physics and statistics. The LAP works closely with the operational personnel who must implement the LLCC in practice to assure that the rules are not only scientifically sound, but also realistic and practical. The details are provided in a companion document entitled "A History of the Lightning Launch Commit Criteria and the Lightning Advisory panel for America's Space program" which is available as NASA Special Publication 2010-216283. As the LFCC have become more complex, launch vehicle operators, range managers, and safety personnel have continuously requested briefings and discussions on the origin of the rules and the rationale behind them. This rationale document was prepared by the LAP to provide the scientific, mathematical, and operational basis for the current LFCC. It is hoped that future revisions of the LFCC/LLCC will be accompanied by corresponding updates to this rationale.

IEEE Transactions on Antennas and Propagation, 2000

Measurements are presented of electric-field derivative (dE/dt) waveforms that were radiated by f... more Measurements are presented of electric-field derivative (dE/dt) waveforms that were radiated by first and subsequent return strokes, stepped, and dart-stepped-leader steps just before return strokes and “characteristic pulses” in normal (negative) cloud-to-ground lightning under conditions of minimal distortion due to ground-wave propagation. The main dE/dt peaks produced by the fast-rising portions of all of these processes are found to have

Journal of Atmospheric and Oceanic Technology, Nov 1, 2007

A "dimensional reduction" ("DR") method is introduced for analyzing lightning field changes (⌬Es)... more A "dimensional reduction" ("DR") method is introduced for analyzing lightning field changes (⌬Es) whereby the number of unknowns in a discrete two-charge model is reduced from the standard eight (x, y, z, Q, xЈ, yЈ, zЈ, QЈ) to just four (x, y, z, Q). The four unknowns (x, y, z, Q) are found by performing a numerical minimization of a chi-square function. At each step of the minimization, an overdetermined fixed matrix (OFM) method is used to immediately retrieve the best "residual source" (xЈ, yЈ, zЈ, QЈ), given the values of (x, y, z, Q). In this way, all eight parameters (x, y, z, Q, xЈ, yЈ, zЈ, QЈ) are found, yet a numerical search of only four parameters (x, y, z, Q) is required. The DR method has been used to analyze lightningcaused ⌬Es derived from multiple ground-based electric field measurements at the NASA Kennedy Space Center (KSC) and U.S. Air Force Eastern Range (ER). The accuracy of the DR method has been assessed by comparing retrievals with data provided by the lightning detection and ranging (LDAR) system at the KSC-ER, and from least squares error estimation theory, and the method is shown to be a useful "stand alone" charge retrieval tool. Since more than one charge distribution describes a finite set of ⌬Es (i.e., solutions are nonunique), and since there can be appreciable differences in the physical characteristics of these solutions, not all DR solutions are physically acceptable. Hence, an alternative and more accurate method of analysis is introduced that uses LDAR data to constrain the geometry of the charge solutions, thereby removing physically unacceptable retrievals. The charge solutions derived from this method are shown to compare well with independent satellite-and ground-based observations of lightning in several Florida storms.

Two approaches are used to characterize how accurately the North Alabama Lightning Mapping Array ... more 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 lar...

Journal of Geophysical Research, 2007

A coordinated aircraft-radar project that investigated the electric fields, cloud microphysics, a... more A coordinated aircraft-radar project that investigated the electric fields, cloud microphysics, and radar reflectivity of thunderstorm anvils near Kennedy Space Center is described. Measurements from two cases illustrate the extensive nature of the microphysics and electric field observations. As the aircraft flew from the edges of anvils into the interior, electric fields very frequently increased abruptly from $1 to >10 kV m 1 even though the particle concentrations and radar reflectivity increased smoothly. The abrupt increase in field usually occurred when the aircraft entered regions with a reflectivity of 10-15 dBZ. We suggest that the abrupt increase in electric field was because the charge advection from the convective core did not occur across the entire breadth of the anvil and because the advection of charge was not constant in time. Also, some long-lived anvils showed enhancement of electric field and reflectivity far downwind of the convective core. Screening layers were not detected near the edges of the anvils. Comparisons of electric field magnitude with particle concentration or reflectivity for a combined data set that included all anvil measurements showed a threshold behavior. When the average reflectivity, such as in a 3-km cube, was less than approximately 5 dBZ, the electric field magnitude was <3 kV m 1. Based on these findings, the Volume Averaged Height Integrated Radar Reflectivity (VAHIRR) is now being used by the NASA, the Air Force, the and Federal Aviation Administration in new Lightning Launch Commit Criteria as a diagnostic for high electric fields in anvils.

Journal of Atmospheric and Oceanic Technology, 2004

Two approaches are used to characterize how accurately the north Alabama Lightning Mapping Array ... more 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 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., anomalous VHF noise sources) are neglected. The detailed spatial distributions of retrieval errors are provided. Even though the two methods are independent of one another, they nevertheless provide remarkably similar results. However, altitude error estimates derived from the two methods differ (the Monte Carlo result being taken as more accurate). Additionally, this study clarifies the mathematical retrieval process. In particular, the mathematical difference between the first-guess linear solution and the Marquardt-iterated solution is rigorously established thereby explaining why Marquardt iterations improve upon the linear solution.

AGU Fall Meeting Abstracts, Dec 1, 2005

Recent studies have shown that U.S. National Lightning Detection Network (NLDN) provides a rich d... more Recent studies have shown that U.S. National Lightning Detection Network (NLDN) provides a rich dataset for exploring the relationship between cloud-to-ground (CG) lightning parameters and the earth&amp;#39;s surface. Of particular interest here is the fact that the rise-time of the radiation field waveforms produced by CG return strokes is quite sensitive to propagation over finite-conductivity ground, since it contains the

Journal of Geophysical Research, 1988

The "transmission-line" model of return-stroke radiation, proposed by Uman and McLain (1970) and ... more The "transmission-line" model of return-stroke radiation, proposed by Uman and McLain (1970) and invoked frequently thereafter to deduce peak currents from remote fields or to estimate propagation velocities from measured fields and currents, has never received a thorough experimental test. During the summer of 1985 at the Kennedy Space Center in Florida, we were able to measure peak currents (with a coaxial shunt), two-dimensional average propagation speeds (with a high-speed streak camera), and electric field waveforms (at 5.15-km range) for a number of subsequent return strokes in rocket-triggered lightning flashes. Because of the temporal ambiguity on the streak-camera films, it has not been possible to identify individual velocity measurements with particular strokes for which current and field data are available. Three multistroke flashes, however, each yielded a tight cluster of velocity measurements and a group of peak field to peak current ratios, though not necessarily for the same strokes. A further six flashes provided more current and field measurements for which no velocity information was obtained, and velocity measurements only are available for still other flashes. It is shown that these data indicate reasonable agreement between the propagation speeds measured with the streak camera and those deduced from the transmission-line model. The previously observed difference between current and radiation-field waveforms suggests a modification of the model, involving two wave fronts traveling upward and downward away from a junction point a short distance above the ground, which substantially improves the agreement between measured and inferred propagation speeds. INTRODUCTION With the development of the rocket and wire technique for triggering lightning discharges [Brook et al., 1961; Newman et al., 1967; Fieux et al., 1978; Hubert et al., 1984; Laroche et al., 1985], measurements of the magnitude and waveform of the electric current at the ground-strike point during subsequent return strokes have become fairly common. (Note that even the sequentially first stroke in a rocket-triggered flash, unless it fails to follow the wire, is considered a subsequent stroke for purposes of comparison with natural lightning.) The behavior of the current in channel segments above the ground, however, is still largely unknown. At present, our best estimates of the spatial and temporal dependences of current in return strokes come from the comparison of remotely measured electric and magnetic fields with those calculated from models of the channel currents. Linet al. [1980] and Master et al. [1981], for example, have proposed a relatively complex model, which assumes the current in a subsequent return stroke to be a superposition of three components: (1) a brief breakdown pulse propagating at a substantial fraction of the speed of light, which communicates ground potential up the channel core; (2) a radial current flowing into the center of the channel after passage of the breakdown pulse (and thence to ground) to discharge the corona sheath left behind by the leader; and (3) a vertically uniform, steady current presumed to be a continuation of the leader current. Lin et al. and Master et al. found that all three components were required to adequately describe the first 100 tts of surface electric and magnetic field waveforms observed simultaneously at both near and far ranges. They then used their model to predict the behavior of the fields above the ground. Regardless of the physical interpretation placed on the various components of the current in this kind of semiempirical model, its value lies in its description of the return stroke in the terms of a few free parameters. These parameters are chosen to fit the fields predicted by the model to those actually measured. The assumption is then made that the model currents approximate the actual currents in certain important respects. Probably the simplest such model was dubbed the "transmission-line model" (TLM) by Urnan and McLain [1970]. This is essentially the breakdown pulse used as one component of the Lin et al. [1980] model. The name refers to the central assumption that the current waveform propagates along the channel in a self-similar manner, as it would in an ideal transmission line. The concept was apparently introduced in this context by Wagner [1960] and further articulated by Dennis and Pierce [1964]. With the additional assumptions that the fixed current waveform propagates with uniform velocity v up a straight, vertical channel from the surface of a perfectly conducting, planar Earth, computation of the fields at the ground becomes particularly simple. For distances D large compared to the height H to which the current has risen at retarded time t-D/c, Urnan et al. [1975] have shown that the surface electric field is vertical and given by

Journal of Geophysical Research, 1989

The NASA Kennedy Space Center and Cape Canaveral Air Force Station are currently operating a larg... more The NASA Kennedy Space Center and Cape Canaveral Air Force Station are currently operating a large network of electric field mills to detect lightning and electrified clouds that might present hazards to ground operations, launches, and landings. Here we summarize recent results of least squares analyses of multistation measurements of field changes that were produced by cloud‐to‐ground (Q model) and intracloud (P model) lightning. The values of the optimum parameters of 113 lightning events that occurred in one small storm on July 11, 1978, and a portion of a large storm on July 6, 1978, are tabulated and graphed. We note that, in both storms, there is considerable symmetry in the direction of P vectors around the Q region and that this pattern is consistent with the classic double‐dipole model of thundercloud charges. We note also that the vertical separation of the Q and P regions depends on the storm intensity.

Natural and triggered lightning are demonstrated hazards to the launch of space vehicles, and the... more Natural and triggered lightning are demonstrated hazards to the launch of space vehicles, and the American space program has responded by establishing the "Lightning Launch Commit Criteria (LLCC)" to mitigate the risk. These LLCC are a complex set of rules with associated Definitions which must be satisfied before the launch of a space vehicle is permitted. The Definitions are an integral part of the LLCC and the term LLCC, as used in this document, is explicitly intended to include those Definitions. They apply to all Federal Government ranges including not only the well-known Eastern Range at Cape Canaveral, Florida, and the Western Range at Vandenberg AFB, California, but also smaller ranges such as the NASA range at Wallops Island, Virginia, the Air Force range at Kwajalein Atoll in the Pacific Ocean, and others. An earlier version of these rules currently applies to all spaceports operating under the jurisdiction of the Federal Aviation Administration (14 CFR 417). The LLCC are developed and approved through a complex process, but the core science and recommendations for precise wording of the operative parts of the rules are provided by a "Lightning Advisory Panel (LAP)" consisting of American scientists working in atmospheric electricity and related disciplines including dynamic meteorology, cloud physics, and statistics. The LAP works closely with the operational personnel who must implement the LLCC in practice to assure that the rules are not only scientifically sound, but also realistic and practical. The details are provided in a companion document entitled "

Since natural and artificially-initiated (or 'triggered') lightning are demonstrated hazards to t... more Since natural and artificially-initiated (or 'triggered') lightning are demonstrated hazards to the launch of space vehicles, the American space program has responded by establishing a set of Lightning Launch Commit Criteria (LLCC) and Definitions to mitigate the risk. The LLCC apply to all Federal Government ranges and have been adopted by the Federal Aviation Administration for application at state-operated and private spaceports. The LLCC and their associated definitions have been developed, reviewed, and approved over the years of the American space program starting from relatively simple rules in the mid-twentieth century (that were not adequate) to a complex suite for launch operations in the early 21 st century. During this evolutionary process, a "Lightning Advisory Panel (LAP)" of top American scientists in the field of atmospheric electricity was established to guide it. This history document provides a context for and explanation of the evolution of the LLCC and the LAP. A companion document on the rationale is currently being prepared by the LAP to provide the physical, mathematical, and operational justification for the current LLCC. Preface Natural and triggered lightning is a demonstrated hazard to the launch of space vehicles, and the American space program has responded by establishing the "Lightning Launch Commit Criteria (LLCC)" to mitigate the risk. These LLCC are a complex set of rules with associated Definitions which must be satisfied before the launch of a space vehicle is permitted. The Definitions are an integral part of the LLCC and the term LLCC as used in this History is explicitly intended to include those Definitions. They apply to all Federal Government ranges including not only the well-known Eastern Range at Cape Canaveral, Florida and the Western Range at Vandenberg AFB, California, but also to smaller ranges such as the NASA range at Wallops Island, Virginia and the Air Force range at Kwajalein Atoll in the Pacific Ocean and others. In addition, these same LLCC have been adopted by the Federal Aviation Administration for application at state-operated and private spaceports. The LLCC are developed and approved through a complex process, but the core science and recommendations for precise wording of the operative parts of the rules are provided by a "Lightning Advisory Panel (LAP)" consisting of American scientists working in atmospheric electricity and related disciplines including cloud physics and statistics. The LAP works closely with the operational personnel who must implement the LLCC in practice to assure that the rules are not only scientifically sound, but also realistic and practical. The LLCC have evolved over the history of the American space program from relatively simple mid-twentieth century rules that proved inadequate to the complex suite that governs launch operations in the early part of the 21 st century. Following the destruction of an Atlas-Centaur launch vehicle by triggered lightning in 1987, the LAP was established to guide the process. Expert guidance is required because there is always a tension between the essential need to fly safely by avoiding lightning strikes and the need to fly economically by avoiding unnecessary launch delays and scrubs. The LLCC have become complex because increased knowledge has permitted exceptions under certain conditions from what are otherwise broad prohibitions to flight. These exceptions reduce the number of occasions under which a launch will be scrubbed for violation of the LLCC when, in fact, it would have been safe to fly. As the LLCC have become more complex, launch vehicle operators, range managers, and safety personnel have continuously requested briefings and discussions on the origin of the rules and the rationale behind them. This history document is designed to provide a historical context and explanation for the origin of the LLCC and the LAP. A companion rationale document is being prepared by the LAP to provide the scientific, mathematical, and operational basis for the current LLCC. Bill Bihner and Jack Ernst (retired) at NASA headquarters provided recollections of the formation of the Peer Review Committee and its evolution into the modern Lightning Advisory Panel. Launa Maier of the KSC Safety and Mission Assurance Directorate provided valuable recollections of the research programs and lightning infrastructure development during the years immediately following the AC 67 accident. In addition to providing a figure and some references for the document, Jennifer Wilson of the KSC Weather Office handled the logistics of several face-to-face meetings of the LAP at KSC. Without these meetings dedicated to this History's organization and production, it could not have been completed. Jennifer Rosenberger of the KSC Launch Processing Directorate did extensive reformatting and copy editing to prepare the original manuscript for public release in this NASA Special Publication series. We appreciate her diligence and attention to detail that substantially reduced the number of errors and inconsistencies in the presentation of the material.

Networks of field mills (FMs) and lightning direction finders (LDFs) have been used to locate lig... more Networks of field mills (FMs) and lightning direction finders (LDFs) have been used to locate lightning over the NASA Kennedy Space Center (KSC) on three storm days. Over 90 percent of all cloud-to-ground (CG) flashes that were detected by the LDFs in the study area were also detected by the FM network. 27 percent of the FM lightning events were correlated with CG flashes detected by the LDFs. About 17 percent of the FM CG events could be fitted to either a monopole or a dipole charge model. These projected FM charge locations are compared to LDF locations, i.e. the ground strike points. We find that 95% of the LDF points are within 12 km of the FM charge, 75% are within 8 km, and 50% are within 4 km. For a storm on July 22, 1988, there was a systematic 5.6 km shift between the FM charge centers and the LDF strike points that might have been caused by the meteorological structure of the storm.

This thesis has been submitted in partial fulfill ment of requirements for an advanced degree at ... more This thesis has been submitted in partial fulfill ment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknow ledgement of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author.

Steinkopff eBooks, 1976

The experimental techniques used to measure the broadband (1 kHz – 10 MHz) electric and magnetic ... more The experimental techniques used to measure the broadband (1 kHz – 10 MHz) electric and magnetic fields produced by lightning are described. Data obtained on lightning return strokes and stepped leaders within 200 km are presented and discussed.

otr, amm htiod lochr_ tmk_ | _O2n-19T REPORTDOCUMENTATION 1. n[po_ m3. z PB88-246376 PAGE _ Title... more otr, amm htiod lochr_ tmk_ | _O2n-19T REPORTDOCUMENTATION 1. n[po_ m3. z PB88-246376 PAGE _ Title mMI _dmlle L Ite_t Om METEOROLOGICAL SUPPORT FOR SPACE OPERATIONS: Review and 7/27/88 Recommendations _J_tlN_(_ &l'm'fm'm;_Oq_nizotkmRept. _. Panel on Meteorological Support for Space Operations L Pm_*mlelOel_lm_mmNemeo_Addmss ]_lqaiectnesk/W_tU_ N_ National Research Council Board on Atmospheric Sciences and Climate IL__,w_ 2101 Constitution Avenue N.W. (_ NASW-4272 Washington, DC 20418 12.$1mmm_knlOqlmtlxatlmtNamea_Addmss IL TytN_ hl3Oft&Pm.lodCmmmcl National Aeronautics and Space Administration Final Study of the current (1987) meteorological support utilized by NASA for space operations with recommendations for improvements. UL_kln_l(Limdl:20Ommm) This report, Meteorological Support for Space OperatiG.ns, reviews the current meteorological support provided to NASA by NOAA, Air Weather Service, and other contractors and offers suggestions for its improvement. These recommendations include improvement in NASA's internal management organizational structure that would accommodate continued improvement in operational weather support, installation of new observing systems, improvement in analysis and forecasting procedures, and the establishment of an Applied Research and Forecasting Facility.

Journal of Geophysical Research, 1989

IEEE Transactions on Antennas and Propagation, 2000

Journal of Atmospheric and Oceanic Technology, Nov 1, 2007

Journal of Geophysical Research, 2007

Journal of Atmospheric and Oceanic Technology, 2004

AGU Fall Meeting Abstracts, Dec 1, 2005

Journal of Geophysical Research, 1988

Journal of Geophysical Research, 1989

Steinkopff eBooks, 1976