Some features of stepped and dart-stepped leaders near the ground in natural negative cloud-to-ground lightning discharges

Abstract. Characteristics of the electric fields produced by stepped and dart-stepped leaders 200 µs just prior to the return strokes during natural negative cloud-to-ground (CG) lightning discharges have been analyzed by using data from a broad-band slow antenna system with 0.08 µs time resolution in southeastern China. It has been found that the electric field changes between the last stepped leader and the first return stroke could be classified in three categories. The first type is characterized by a small pulse superimposed on the abrupt beginning of the return stroke, and accounts for 42% of all the cases. The second type accounts for 33.3% and is characterized by relatively smooth electric field changes between the last leader pulse and the following return stroke. The third type accounts for 24.7%, and is characterized by small pulses between the last recognizable leader pulse and the following return stroke. On the average, the time interval between the successive leader pulses prior to the first return strokes and subsequent return strokes was 15.8 µs and 9.4 µs, respectively. The distribution of time intervals between successive stepped leader pulses is quite similar to Gaussian distribution while that for dart-stepped leader pulses is more similar to a log-normal distribution. Other discharge features, such as the average time interval between the last leader step and the first return stroke peak, the ratio of the last leader pulse peak to that of the return stroke amplitude are also discussed in the paper.Key words. Meteology and atmospheric dynamics (atmospheric electricity; lightning) – Radio science (electromagnetic noise and interference)

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Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp

Annales Geophysicae ◽

10.5194/angeo-22-511-2004 ◽

2004 ◽

Vol 22 (2) ◽

pp. 511-525 ◽

Cited By ~ 12

Author(s):

K. Oksavik ◽

F. Søraas ◽

J. Moen ◽

R. Pfaff ◽

J. A. Davies ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Broad Band ◽

Spectral Width ◽

Hf Radar ◽

Optical Data ◽

Low Energy Electrons ◽

Field Lines ◽

Auroral Phenomena ◽

Electric Fields And Currents

Abstract. In this paper we discuss counterstreaming electrons, electric field turbulence, HF radar spectral width enhancements, and field-aligned currents in the southward IMF cusp region. Electric field and particle observations from the FAST spacecraft are compared with CUTLASS Finland spectral width enhancements and ground-based optical data from Svalbard during a meridional crossing of the cusp. The observed 630nm rayed arc (Type-1 cusp aurora) is associated with stepped cusp ion signatures. Simultaneous counterstreaming low-energy electrons on open magnetic field lines lead us to propose that such electrons may be an important source for rayed red arcs through pitch angle scattering in collisions with the upper atmosphere. The observed particle precipitation and electric field turbulence are found to be nearly collocated with the equatorward edge of the optical cusp, in a region where CUTLASS Finland also observed enhanced spectral width. The electric field turbulence is observed to extend far poleward of the optical cusp. The broad-band electric field turbulence corresponds to spatial scale lengths down to 5m. Therefore, we suggest that electric field irregularities are directly responsible for the formation of HF radar backscatter targets and may also explain the observed wide spectra. FAST also encountered two narrow highly structured field-aligned current pairs flowing near the edges of cusp ion steps. Key words. Ionosphere (electric fields and currents). Magnetosphere physics (magnetopause, cusp, and boundary layers; auroral phenomena)

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The interchange of electricity between thunderclouds and the Earth

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1928.0049 ◽

1928 ◽

Vol 118 (779) ◽

pp. 252-262 ◽

Cited By ~ 40

Keyword(s):

Electric Fields ◽

Negative Charge ◽

Atmospheric Electricity ◽

Outstanding Problem ◽

The Earth ◽

Fine Weather ◽

Lightning Discharges ◽

Point Discharge ◽

Potential Gradients ◽

Strong Electric Fields

Prof. C. T. R. Wilson has suggested that the exchange of electricity between thunderclouds and the ground may be an important factor in the maintenance of the earth’s negative charge, the replenishment of which, in view of the fine-weather air-earth current, is an outstanding problem in atmospheric electricity. He has shown that such an exchange can take place in three ways, by the momentary currents due to lightning discharges between the cloud and the ground, by the convection currents carried by rain, and by the continuous currents carried by ions moving in the powerful electric fields below the cloud. This last effect may be expected to be considerable since such ions will be produced in quantity as a result of point-discharges from trees and bushes below the cloud. In the present paper an attempt is made to estimate the magnitudes of these three factors in the exchange. Before describing the measurements, it may be recalled that in two studies of the strong electric fields below these clouds, it has been found that negative potential gradients are very much more frequent and considerably stronger than positive ones. Indeed, occasions of strong positive fields below active thunderclouds are so rare as to be negligible, and the predominance of strong negative fields must cause the point-discharge currents to be mainly upwardly directed. The earth must therefore gain a negative charge from this effect.

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Effects of multiple scatter on the propagation and absorption of electromagnetic waves in a field-aligned-striated cold magneto-plasma: implications for ionospheric modification experiments

Annales Geophysicae ◽

10.5194/angeo-20-41-2002 ◽

2002 ◽

Vol 20 (1) ◽

pp. 41-55 ◽

Cited By ~ 8

Author(s):

T. R. Robinson

Keyword(s):

Electric Fields ◽

Plasma Density ◽

Electromagnetic Waves ◽

Broad Band ◽

Radio Science ◽

Multiple Scatter ◽

Electromagnetic Test ◽

Ionospheric Modification ◽

Hybrid Resonance ◽

Single Scatter

Abstract. A new theory of the propagation of low power electromagnetic test waves through the upper-hybrid resonance layer in the presence of magnetic field-aligned plasma density striations, which includes the effects of multiple scatter, is presented. The case of sinusoidal striations in a cold magnetoplasma is treated rigorously and then extended, in an approximate manner, to the broad-band striation spectrum and warm plasma cases. In contrast to previous, single scatter theories, it is found that the interaction layer is much broader than the wavelength of the test wave. This is due to the combined electric fields of the scattered waves becoming localised on the contour of a fixed plasma density, which corresponds to a constant value for the local upper-hybrid resonance frequency over the whole interaction region. The results are applied to the calculation of the refractive index of an ordinary mode test wave during modification experiments in the ionospheric F-region. Although strong anomalous absorption arises, no new cutoffs occur at the upper-hybrid resonance, so that in contrast to the predictions of previous single scatter theories, no additional reflections occur there. These results are consistent with observations made during ionospheric modification experiments at Tromsø, Norway.Key words. Ionosphere (active experiments; ionospheric irregularities) Radio science (ionospheric propagation)

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First in situ measurement of electric field fluctuations during strong spread F in the Indian zone

Annales Geophysicae ◽

10.1007/s00585-000-0523-y ◽

2000 ◽

Vol 18 (5) ◽

pp. 523-531 ◽

Cited By ~ 4

Author(s):

H. S. S. Sinha ◽

S. Raizada

Keyword(s):

Electric Field ◽

Electron Density ◽

Electric Fields ◽

Vertical Direction ◽

Intermediate Scale ◽

Radio Science ◽

Ionospheric Physics ◽

Vertical Electric Field ◽

Field Fluctuations ◽

Spread F

Abstract. An RH-560 rocket flight was conducted from Sriharikota rocket range (SHAR) (14°N, 80°E, dip 14°N) along with other experiments, as a part of equatorial spread F (ESF) campaign, to study the nature of irregularities in electric field and electron density. The rocket was launched at 2130 local time (LT) and it attained an apogee of 348 km. Results of vertical and horizontal electric field fluctuations are presented here. Scale sizes of electric field fluctuations were measured in the vertical direction only. Strong ESF irregularities were observed in three regions, viz., 160-190 km, 210-257 km and 290-330 km. Some of the valley region vertical electric field irregularities (at 165 km and 168 km), in the intermediate-scale size range, observed during this flight, show spectral peak at kilometer scales and can be interpreted in terms of the image striation theory suggested by Vickrey et al. The irregularities at 176 km do not exhibit any peak at kilometer scales and appear to be of a new type. Scale sizes of vertical electric field fluctuations showed a decrease with increasing altitude. The most prominent scales were of the order of a few kilometers around 170 km and a few hundred meters around 310 km. Spectra of intermediate-scale vertical electric field fluctuations below the base of the F region (210-257 km) showed a tendency to become slightly flatter (spectral index n = -2.1 ± 0.7) as compared to the valley region (n = -3.6 ± 0.8) and the region below the F peak (n = -2.8 ± 0.5). Correlation analysis of the electron density and vertical electric field fluctuations suggests the presence of a sheared flow of current in 160-330 km region.Keywords: Ionosphere (Electric fields and currents; ionospheric irregularities); Radio science (ionospheric physics)

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Asymptotic expansion of pair production probability in a time-dependent electric field

International Journal of Modern Physics A ◽

10.1142/s0217751x15502103 ◽

2015 ◽

Vol 30 (35) ◽

pp. 1550210

Author(s):

Takashi Arai

Keyword(s):

Asymptotic Expansion ◽

Electric Field ◽

Electric Fields ◽

Quantum Electrodynamics ◽

Strong Field ◽

Order Term ◽

Constant Electric Field ◽

Particle Creation ◽

Single Pulse ◽

Time Interval

We study particle creation in a single pulse of an electric field in scalar quantum electrodynamics. We investigate the parameter condition for the case where the dynamical pair creation and Schwinger mechanism respectively dominate. Then, an asymptotic expansion for the particle distribution in terms of the time interval of the applied electric field is derived. We compare our result with particle creation in a constant electric field with a finite-time interval. These results coincide in an extremely strong field, however they differ in general field strength. We interpret the reason of this difference as a nonperturbative effect of high-frequency photons in external electric fields. Moreover, we find that the next-to-leading-order term in our asymptotic expansion coincides with the derivative expansion of the effective action.

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Electric Field Sensor for Small Unmanned Aerial Vehicles

10.5194/egusphere-egu2020-7768 ◽

2020 ◽

Author(s):

Stefan Chindea ◽

Keri Nicoll

Keyword(s):

Electric Field ◽

Unmanned Aerial Vehicles ◽

Electric Fields ◽

Atmospheric Electricity ◽

Data Logging ◽

Electric Field Sensor ◽

Aerial Vehicles ◽

Small Uav ◽

Field Sensor ◽

Sensor Package

Characterisation of the vertical variation in the atmospheric electric field has been made for many decades, but normally in an ad-hoc manner, using instrumented weather balloons or manned aircraft, which are expensive to fly.&#160; Such vertical measurements are required to measure the ionospheric potential and to characterise electric fields with clouds (both thunderstorm and non thunderstorm clouds) to understand the charging processes within them.&#160;Advances in electronics and battery technology has meant that small Unmanned Aerial Vehicles (UAVs) have now become available as a new science platform. These measurement platforms address many of the problems associated with manned aircraft while allowing in-situ measurements with an increased level of control and repeatability when compared to weather balloons. Despite their potential advantages, one of the main challenges to using UAVs for atmospheric electricity research is the lack of small, lightweight sensors which are commercially available. To overcome this barrier, this work describes the development of a lightweight, miniaturised electric field sensor to be integrated with a small UAV (<7kg, wingspan 2m).&#160;The sensor has been designed to allow measurements of the electric field intensities typical of non-thunderstorm low altitude (<6000 ft) clouds with a typical range of 0-2.5kV/m. It is based on the concept of an electric field mill, but with a translational shield rather than a rotating vane model. This allows the sensor to fit neatly within the wing of a small UAV, rather than the need to be mounted in the nose.&#160; A custom designed 3D printed housing contains all elements of the sensor package, with the translational shield movement and data logging controlled by an onboard programmable microcontroller. This work will focus on the details regarding the experimental characterisation of the sensor package with a particular focus on the key influences of the integration with the airborne platform.

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Microsensor for Atmospheric Electric Fields

10.5194/egusphere-egu2020-8562 ◽

2020 ◽

Author(s):

Andreas Kainz ◽

Wilfried Hortschitz ◽

Matthias Kahr ◽

Franz Keplinger ◽

Gerhard Diendorfer

Keyword(s):

Field Strength ◽

Electric Field ◽

Resonance Frequency ◽

Electric Fields ◽

Low Cost ◽

Atmospheric Electricity ◽

Laser Doppler Vibrometer ◽

Underlying Mechanism ◽

Thunderstorm Activity ◽

Resonance Frequencies

Many phenomena of atmospheric electricity are still not well understood, as most of the processes involved can only be observed in real nature. For this purpose, reliable and stable measurements of the electric field strength are mandatory. While for high-frequency fields, there exists a large variety of equipment, in the quasi-static and especially static regime, such systems are scarce. The &#8222;standard&#8220; device for the application is the electrostatic field mill which uses a rotating, electrically grounded shutter electrode to alternatingly expose and shield measurement electrodes to/from the electric field. While they achieve good-enough resolution, there are many inherent problems associated with the measurement principle, such as mechanical wear, massive field distortions, size and weight. As a consequence, they are typically installed at a fixed points and cannot be easily moved or mounted. Miniaturised field mills have minimised some of these issues, the shutter priniciple leads to very fragile structures.We present an alternative way of measuring low-frequency and static electric fields (E-field), which does not suffer from the hindering drawbacks of field mills. The underlying mechanism converts the E-field to a mechanical oscillation of a microelectromechanical system (MEMS). This is achieved by applying an AC voltage to a compliant mechanical structure. As a result of the AC voltage, alternating charges accumulate at the surface of the MEMS. When exposed to the E-field, this leads to a force deflecting the structure at a known frequency. For this kind of active mechanism, the power consumption is minimal, since the current flow is practically zero. Therefore, the system can be used in a floating way without grounded connections and therefore minimum field distortions. The mechanical motion can then be read out optically, also to avoid field distortions and backaction. If the system is driven at the mechanical resonance, the quality factor can be exploited to boost the sensitivity. In this case the bandwidth of the system ranges from 0&#160;Hz to twice the resonance frequency.Several MEMS sensors with different resonance frequencies (ranging from ~100 Hz to ~1 kHz) have been fabricated and tested in the laboratory. The sensors have been mounted between two parallel field plates supplied with a DC voltage, which provides the static electric field. A tiny hole in one of the field plates allowed for optical readout of the sensor movement with a laser-Doppler vibrometer (Polytec MSA-400). The sensors have been tested for different field strengths (10 V/m &#8211; 30 kV/m) and different AC voltages (0.02 V &#8211; 20 V) confirming linearity in both quantities. In terms of field strength, a resolution as good as ~25 V/m was achieved for a sensor with a resonance frequency of 167 Hz. These promising results substantiate that this sensor is a potentially low-weight, low-cost alternative for classical field mills. The next steps will be to investigate long-term stability and environmental effects on the sensor (temperature, humidity) and, finally, installation and test in the open area during fair weather and thunderstorm activity.

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Equatorial electrojet as part of the global circuit: a case-study from the IEEY

Annales Geophysicae ◽

10.1007/s00585-998-0698-1 ◽

1998 ◽

Vol 16 (6) ◽

pp. 698-710 ◽

Cited By ~ 21

Author(s):

A. T. Kobea ◽

C. Amory-Mazaudier ◽

J. M. Do ◽

H. Lühr ◽

E. Houngninou ◽

...

Keyword(s):

Electric Field ◽

Geomagnetic Storm ◽

Electric Fields ◽

High Latitude ◽

Large Scale ◽

Equatorial Electrojet ◽

Doppler Frequency ◽

Time Interval ◽

Ground Field ◽

Equatorial Latitude

Abstract. Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they affect the normal eastward Sq field. This paper presents an analysis of ground magnetic field and ionospheric electrodynamic data related to the geomagnetic storm which occured on 27 May 1993 during the International Equatorial Electrojet Year (IEEY) experiment. This storm-signature analysis on the auroral, mid-latitude and equatorial ground field and ionospheric electrodynamic data leads to the identification of a sensitive response of the equatorial electrojet (EEJ) to large-scale auroral return current: this response consists in a change of the eastward electric field during the pre-sunrise hours (0400-0600 UT) coherently to the high-, mid-, and equatorial-latitude H decrease and the disappearance of the EEJ irregularities between the time-interval 0800-0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA) caused by the high-latitude penetrating electric field. The strengthening of these irregularities attested by the Doppler frequency increase tracks the H component at the equator which undergoes a rapid increase around 0800 UT. The ∆H variations observed at the equator are the sum of the following components: SR, DP, DR, DCF and DT.Keywords. Equatorial electrojet · Magnetosphere-ionosphere interactions · Electric fields and currents · Auroral ionosphere · Ionospheric disturbances

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Electric Mode Excitation in the Atmosphere by Magnetospheric Impulses and ULF Waves

Frontiers in Earth Science ◽

10.3389/feart.2020.619227 ◽

2021 ◽

Vol 8 ◽

Author(s):

V. A. Pilipenko ◽

E. N. Fedorov ◽

V. A. Martines-Bedenko ◽

E. A. Bering

Keyword(s):

Electric Field ◽

Electric Fields ◽

Electromagnetic Waves ◽

Atmospheric Electricity ◽

Theoretical Estimate ◽

Potential Gradient ◽

Atmospheric Electric Field ◽

Iri Model ◽

Excitation Rate ◽

Magnetospheric Field

Variations of vertical atmospheric electric field Ez have been attributed mainly to meteorological processes. On the other hand, the theory of electromagnetic waves in the atmosphere, between the bottom ionosphere and earth’s surface, predicts two modes, magnetic H (TE) and electric E (TH) modes, where the E-mode has a vertical electric field component, Ez. Past attempts to find signatures of ULF (periods from fractions to tens of minutes) disturbances in Ez gave contradictory results. Recently, study of ULF disturbances of atmospheric electric field became feasible thanks to project GLOCAEM, which united stations with 1 sec measurements of potential gradient. These data enable us to address the long-standing problem of the coupling between atmospheric electricity and space weather disturbances at ULF time scales. Also, we have reexamined results of earlier balloon-born electric field and ground magnetic field measurements in Antarctica. Transmission of storm sudden commencement (SSC) impulses to lower latitudes was often interpreted as excitation of the electric TH0 mode, instantly propagating along the ionosphere–ground waveguide. According to this theoretical estimate, even a weak magnetic signature of the E-mode ∼1 nT must be accompanied by a burst of Ez well exceeding the atmospheric potential gradient. We have examined simultaneous records of magnetometers and electric field-mills during >50 SSC events in 2007–2019 in search for signatures of E-mode. However, the observed Ez disturbance never exceeded background fluctuations ∼10 V/m, much less than expected for the TH0 mode. We constructed a model of the electromagnetic ULF response to an oscillating magnetospheric field-aligned current incident onto the realistic ionosphere and atmosphere. The model is based on numerical solution of the full-wave equations in the atmospheric-ionospheric collisional plasma, using parameters that were reconstructed using the IRI model. We have calculated the vertical and horizontal distributions of magnetic and electric fields of both H- and E-modes excited by magnetospheric field-aligned currents. The model predicts that the excitation rate of the E-mode by magnetospheric disturbances is low, so only a weak Ez response with a magnitude of ∼several V/m will be produced by ∼100 nT geomagnetic disturbance. However, at balloon heights (∼30 km), electric field of the E-mode becomes dominating. Predicted amplitudes of horizontal electric field in the atmosphere induced by Pc5 pulsations and travelling convection vortices, about tens of mV/m, are in good agreement with balloon electric field and ground magnetometer observations.

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The effect of magnetic substorms on near-ground atmospheric current

Annales Geophysicae ◽

10.1007/s00585-001-1623-z ◽

2000 ◽

Vol 18 (12) ◽

pp. 1623-1629 ◽

Cited By ~ 15

Author(s):

E. Belova ◽

S. Kirkwood ◽

H. Tammet

Keyword(s):

Electric Fields ◽

Statistical Significance ◽

Atmospheric Electricity ◽

Electric Circuit ◽

Local Times ◽

Wire Antenna ◽

Time Interval ◽

Early Recovery ◽

Superposed Epoch Analysis ◽

Electric Fields And Currents

Abstract. Ionosphere-magnetosphere disturbances at high latitudes, e.g. magnetic substorms, are accompanied by energetic particle precipitation and strong variations of the ionospheric electric fields and currents. These might reasonably be expected to modify the local atmospheric electric circuit. We have analysed air-earth vertical currents (AECs) measured by a long wire antenna at Esrange, northern Sweden during 35 geomagnetic substorms. Using superposed epoch analysis we compare the air-earth current variations during the 3 h before and after the time of the magnetic X-component minimum with those for corresponding local times on 35 days without substorms. After elimination of the average daily variation we can conclude that the effect of substorms on AEC is small but distinguishable. It is speculated that the AEC increases observed during about 2 h prior to the geomagnetic X-component minimum, are due to enhancement of the ionospheric electric field. During the subsequent 2 h of the substorm recovery phase, the difference between "substorm" and "quiet" atmospheric currents decreases. The amplitude of this "substorm" variation of AEC is estimated to be less than 50% of the amplitude of the diurnal variation in AEC during the same time interval. The statistical significance of this result was confirmed using the Van der Waerden X-test. This method was further used to show that the average air-earth current and its fluctuations increase during late expansion and early recovery phases of substorms.Key words: Ionosphere (electric fields and currents) · Magnetospheric physics (storms and substorms) · Meteorology and atmospheric dynamics (atmospheric electricity)

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