Effect of <i>E</i>‐field mill location on accuracy of electric field measurements with instrumented airplane

Mazur, Vladislav; Ruhnke, Lothar H.; Rudolph, Terence

doi:10.1029/jd092id10p12013

Cited by 20 publications

(9 citation statements)

References 6 publications

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“…For comparison the runaway electron avalanche threshold field is about 150 kV/m at a 5 km altitude. We note that since the measurement of electric field strengths from aircraft may be influenced by the conducting aircraft skin and other disturbances caused by the aircraft's passage, the older quoted numbers, which were acquired before these effects were understood, may be of questionable accuracy [ Mazur et al , 1987].…”

Section: Discussionmentioning

confidence: 99%

Estimation of the fluence of high‐energy electron bursts produced by thunderclouds and the resulting radiation doses received in aircraft

et al. 2010

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[1] Using recent X-ray and gamma-ray observations of terrestrial gamma-ray flashes (TGFs) from spacecraft and of natural and rocket-triggered lightning from the ground, along with detailed models of energetic particle transport, we calculate the fluence (integrated flux) of high-energy (million electronvolt) electrons, X rays, and gamma rays likely to be produced inside or near thunderclouds in high electric field regions. We find that the X-ray/gamma-ray fluence predicted for lightning leaders propagating inside thunderclouds agrees well with the fluence calculated for TGFs, suggesting a possible link between these two phenomena. Furthermore, based on reasonable meteorological assumptions about the magnitude and extent of the electric fields, we estimate that the fluence of high-energy runaway electrons can reach biologically significant levels at aircraft altitudes. If an aircraft happened to be in or near the high-field region when either a lightning discharge or a TGF event is occurring, then the radiation dose received by passengers and crew members inside that aircraft could potentially approach 0.1 Sv (10 rem) in less than 1 ms. Considering that commercial aircraft are struck by lightning, on average, one to two times per year, the risk of such large radiation doses should be investigated further.

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Section: Discussionmentioning

confidence: 99%

Estimation of the fluence of high‐energy electron bursts produced by thunderclouds and the resulting radiation doses received in aircraft

et al. 2010

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“…Less symmetric mill placements than those used on SPTVAR would require a full matrix inversion of the set of equations (2). This would necessitate determination of all the matrix coefficients such as done by Laroche [1986], and would entail aJl the uncertainties discussed by Mazur [1987].…”

Section: Charge Subtractionmentioning

confidence: 99%

Electric charge acquired by airplanes penetrating thunderstorms

Jones¹

1990

J. Geophys. Res.

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Three airplanes--a sailplane, a piston powered sailplane, and a twin turboprop--have been instrumented to measure electric fields inside electrified clouds and the net electric charge on the airplanes. In unelectrified clouds the powered airplanes become negatively charged during collisions with liquid cloud water droplets whereas the sailplane does not. In thunderstorm clouds, several airplane charging mechanisms are found to operate. These involve collisions with liquid water droplets of the cloud and the shedding of polarization charge in the presence of strong electric fields. For these charging processes, the sign of the acquired charge depends on the sign of the component of the atmospheric electric field along the direction of flight. When the amounts of charge on the powered airplanes are small, the engine exhaust acts to discharge the airplane, while for larger charges, corona emission becomes the predominant mechanism of discharge. about the evolving•charge structure of electrified clouds uti-V• = A•xEx.4 + A•yEy.4 + A•zEz.4 + A•QQ (2) lize airplanes instrumented to measure the electric field in-where the index I identifies the mounting location of the side clouds. However, measurement of the electric field in particular mill and the A terms are mill location dependent clouds by an airplane is complicated because of the distot-coefficients. With a sufficient number of field mills at approtions of that field, EcLorrz>, by the airplane and because of priate locations on the airplane it is possible, in principle, to ß the superimposed field, /•Q, due to the net electric charge, determine Ex, Ey, Ez, and Q. However, determination of Q, that the airplane usually acquires. Additionally, there is t•cLorrD may be difficult in the presence of charge plumes often yet another superimposed field which further compli-since, being highly variable in character, charge plumes are cates the task of determining the cloud electric field. The not easily modeled. charge density on the surfac•e of the airplane due to the cloud The first step in extracting the ambient field components field and airplane charge, Q, varies from place to place on from the mill signals involves subtracting that part of the the airplane's surface and often becomes sufficiently large signal due to the airplane charge. This is most easily done at particular locations for the electric field strength there to when pairs of mills face in opposite directions along a given cause electrical breakdown of the air. The resulting corona airplane coordinate direction, since, although the A• for generates plumes of charge leaving the airplane [Stirnmel et the two opposed mills always have the same sign, the princial., 1946]. Thhs, a third corltribution to the electric field at pal field component coefficients, the A•r, for example, then the surfac e'of the airplane, can be caused by charge plumes have opposite signs. Figure i shows the configuration of emitted from the airplane. The engine exhaust plume also the SPTVAR (Special Purpose Test Vehicle for Atmosphe...

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“…The P‐3's electric field meter system is described by Black and Hallett [1999], and the T‐28's by Ramachandran et al [1996] and Mo et al [1999]. From these accurate observations of the local electric field at different points on an airframe, a somewhat less accurate estimate of the ambient electric field can be obtained, as described by, for example, Mazur et al [1987], Winn [1993], or Koshak et al [1994]. In the discussion that follows we focus on just the E z component of the total electric field vector and use the convention that E z is positive when negative charge is above and/or positive charge is below the measurement altitude.…”

Section: Introductionmentioning

confidence: 99%

Horizontal structure of the electric field in the stratiform region of an Oklahoma mesoscale convective system

Mo¹

2003

J. Geophys. Res.

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[1] This analysis combines vertical electric field components E z observed by two research aircraft flying horizontally at two levels, with vertical soundings of thermodynamic parameters and E z made by five balloons, to produce a quasi-threedimensional view of the space charge distribution in the trailing stratiform cloud region behind a mesoscale convective system (MCS) that developed in central Oklahoma late in the afternoon of 2 June 1991. The balloons were launched serially at one-hour intervals from two sites separated by 80 km along a north-south line as the MCS moved eastward, yielding two east-west time-height cross-sections of the E z structure within the quasi-steady state trailing stratiform region behind the MCS. The balloon measurements are consistent with a vertical stack of five rearward-and downwardsloping horizontal sheets of charge of alternating polarity, beginning at the bottom with a negative charge layer below the 0°C level and a positive layer near the 0°C level. This structure persisted for more than 2 hours. The two aircraft flew back and forth along a north-south line through the balloon launch sites during the balloon launch period. Aircraft measurements demonstrated that the vertical electric field (E z ) at constant altitude varied in the north-south direction. The peak magnitudes of E z deduced from the airborne instrument systems agreed with the magnitudes deduced from the balloon measurements at the aircraft altitudes of 4.5 km and 5.8 km AGL. Rapid reversals in polarity of E z with peak magnitude >50 kV m À1 observed by the aircraft at 4.5 km, just above the 0°C level, confirms the thin concentrated positive charge layer observed there by balloons and suggests that this charge layer is undulating above and below 4.5 km altitude, at least in the north-south direction. Microphysically, this layer contained large aggregates and pockets of low cloud liquid water concentration. At the 5.8 km level, the polarity of E z was always positive but the magnitude varied from zero to 25 kV m À1 . Aircraft-observed E z at both altitudes varied on horizontal scales of $10 km or greater at both levels, suggesting that the charge density derived using the one-dimensional infinite-layer Gauss's law approximation applied to the balloon soundings of E z is valid in this study. These observations show that layers of charge can persist for hours as they advect rearward in a storm-relative sense, possibly due to continuing in situ charge separation, and/or due to weak dispersion, slow recombination and slow settling of charge attached to low mobility low terminal velocity ice hydrometeors.

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Effect of E‐field mill location on accuracy of electric field measurements with instrumented airplane

Cited by 20 publications

References 6 publications

Estimation of the fluence of high‐energy electron bursts produced by thunderclouds and the resulting radiation doses received in aircraft

Estimation of the fluence of high‐energy electron bursts produced by thunderclouds and the resulting radiation doses received in aircraft

Electric charge acquired by airplanes penetrating thunderstorms

Horizontal structure of the electric field in the stratiform region of an Oklahoma mesoscale convective system

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