Vertical Component Of Electric Field Research Articles

Weather factor effects on electric parameters in the lower atmosphere

In order to study the factors influencing the formation of the vertical component of atmospheric electric field (AEF) strength Ez, the data on meteorological parameters (atmospheric pressure, air temperature, and snow depth) are applied, as well as the data of radon Rn emanation into the atmosphere. Determined is the seasonal dependence on the radon emanation to the atmospheric surface layer due to the decrease in the upper soil layer permeability in wintertime that results in the decrease in the surface layer ionization which explains the difference between the maximum and minimum values of electric field strength within the annual variations amounting to ∼100 V/m for the observational period. It is demonstrated that during the negative mean diurnal temperatures (November-April), the cyclone arrival from southern directions is accompanied by significant decrease in AEF Ez due to the increase in the radon flow under the influence of considerable fall of atmospheric pressure and dramatic warming by 10–15°C resulting in the increase in upper soil layer permeability.

Comparison of the low-frequency variations of the vertical and horizontal components of the electric background field at the sea bottom

Natural electric field variations are measured at the sea bottom over long periods of time by means of stationary, vertical, and horizontal galvanic antennas. We compare the power spectra of the vertical and horizontal field components and the extent to which they may be reduced by standard averaging techniques. Although the raw spectra of the vertical and horizontal components do not differ greatly, the difference in the spectra after averaging is significantly greater. Most significantly, in the frequency range between 0.0005 and 0.03 Hz, this averaging scheme suppresses the vertical electric field component more strongly than the horizontal component.

Settlement process of radioactive dust to the ground inferred from the atmospheric electric field measurement

Abstract. Radioactive materials from the accident at Fukushima Dai-ichi nuclear power plant (FNPP) in March 2011 spread over a large area, increasing the atmospheric electric conductivity by their ionizing effect, and reducing the vertical (downward) component of the DC electric field near the ground, or potential gradient (PG). PG data at Kakioka, 150 km away from the FNPP, showed independent changes compared to the radiation dose rate, and a comparison of these data revealed the local dynamics of the radioactive dust. (1) The initial drop of the PG to almost zero during 14–15 March is most likely due to radioactive dust suspended in the air near the ground during cloudy weather. (2) An episode of PG increase to more than 50 V m−1 on 16 March is most likely due to the re-suspension of the radioactive dust from the surface and subsequent removal from Kakioka by the strong wind from the non-contaminated area. (3) Low but finite values of the PG during 16–20 March most likely reflect a reduced amount of radioactive material near the ground after the above wind transported away the majority of the suspended radioactive dust. (4) Very low values of the PG after substantial rain on 20–22 March most likely reflect settlement of the radioactive material by rain-induced fallout. (5) Temporal recovery of daily variations from the end of March to the middle of April with low nighttime fair-weather baseline PG most likely reflects re-suspension of the radioactive dust into the air from the ground and trees, and subsequent transport to the other region or fallout to the ground until late April. (6) Weakening of the daily variation and gradual recovery of the nighttime fair-weather baseline after mid-April suggests a complete settlement of the radioactive material to the ground with partial migration to the subsurface.

Lightning electromagnetic radiation over a stratified conducting ground: 2. Validity of simplified approaches

In the first part of this paper, the rigorous theory describing the electromagnetic field radiated by a lightning return stroke over a two-layered conducting ground was presented and the exact expressions for the lightning electromagnetic fields were developed and discussed. In this part of the paper, the theory along with its time domain numerical evaluation algorithm is used for the assessment of the validity of simplified approaches proposed in the literature for the vertical electric and horizontal magnetic field components. The simplified approaches are based on the concept of ground surface impedance and its corresponding attenuation function. It is shown that the results obtained using the simplified approaches are in excellent agreement with exact results in both near (50 m) and intermediate (1000 m) distance range. However, since the vertical electric and azimuthal magnetic field components are not appreciably affected by the ground finite conductivity, they can also be evaluated assuming the ground as a perfectly conducting ground. On the other hand, the horizontal electric field above a horizontally stratified ground is very much affected by the ground electrical parameters. Its waveform is characterized by an early negative excursion due to the currents flowing into the ground followed by a late time positive excursion which is due to the elevation of the observation point from the ground level. The magnitude of the negative peak is sharper for subsequent return strokes than first return strokes and is higher for lower conducting grounds. A new formula is proposed for the evaluation of the horizontal electric field at a given height above the air-ground interface. The formula can be viewed as the generalization of the Cooray-Rubinstein formula for the case of a two-layer ground. We show that the new formula is able to reproduce in a satisfactory manner the horizontal electric field above a two-layer ground. The proposed formulation is, however, less accurate at distances as close to 10 m from the channel base and for very poor ground conductivity (0.0001 S/m).

The effect and precursors of the earthquake of August 28, 2008, in the vertical component of the electric field in Lake Baikal

842 Since 2003, continuous recording of the vertical component of the natural electric field on the bot� tom–surface basis has been performed in Lake Baikal in the basin of the South Baikal deep depression. The instrumental setup is located in the southwestern part of the lake in the region of the Baikal neutrino tele� scope NT�200 (Institute for Nuclear Research, Rus� sian Academy of Sciences). It is a vertical electric antenna grounded in the water with nonpolarizing lead electrodes located at a distance of 1250 m (the depth of the place is 1350 m). The recording of the variations in the field was performed using autono�

On the Measurement and Calculation of Horizontal Electric Fields From Lightning

In this paper, we discuss two issues related to the measurement and calculation of the horizontal electric fields from lightning. On the one hand, there is an inherent difficulty in measuring the horizontal electric field component from lightning because of the overshadowing effect of the vertical electric field component which, depending on the distance to the lightning channel, the ground conductivity, and the height of the observation point can be one to two orders of magnitude larger than the horizontal electric field component. Consequently, even a small tilt of the measuring antenna would result in a noticeable contamination of the measured horizontal waveform. This may explain the fact that data on horizontal electric fields are very scarce. Numerical simulations show that, for a ground conductivity of 0.0025 S/m, the resulting error for a one-degree sensor tilt in the field peak is about 20% for distances ranging from 60 to 500 m. For strikes to a 100-m-tall tower, the resulting errors are found to be slightly smaller (about 10% to 15% for the first peak). The second issue dealt with in this paper is the computation methods of the horizontal electric field. In this regard, some authors have emphasized the importance of taking into account the so-called conduction current in the calculation of nearby horizontal electric fields. We show in this paper that the conducted contribution is automatically taken into account when using the general solutions of Maxwell's equations or obtained by exact numerical simulations. In this case, there is no need to consider separately any other contributions because the solution yields the total horizontal electric field, taking into account both the radiation from the channel and the current flowing into the ground. However, a “conducted contribution” needs indeed to be taken into account separately when high-frequency approximate solutions are used for the evaluation of the electric field. At very close distances to the lightning strike location, the current distribution in the ground may be highly nonuniform because of surface arcing and plasma channel formations. Given the random nature of these phenomena, it is virtually impossible to gain detailed knowledge of the current distribution and, hence, to evaluate the resulting horizontal electric field near the strike point. Based on the results and discussion presented in this paper, we recommend taking special care when measuring the horizontal electric field from lightning to minimize the contaminating effect of the vertical electric field. It is important that both components (vertical and horizontal) be measured simultaneously to evaluate possible contamination of the horizontal field.

Characteristics Analysis for the Spherical Antenna of a Seismometer

A seismometer for vertical electric field component of natural ELF and ULF electromagnetic waves measurement by using spherical antenna is introduced. The goal of the proposed seismometer is to provide continuous observation of the natural electromagnetic emissions related to the coupling of seismic activity with the outer spaces and ionosphere, which utilize a spherical aluminum electrode 78mm in diameter with embedded enhanced preamplifier circuits that built to mount flush with the ground so as to preserve the configuration in which the antenna operates. The presented seismometer has a wide frequency response at low frequencies, it's typical sensitivity in the frequency range DC to 30MHz are shown to be and ,the dynamical range is >50dB in ELF and VLF and about 25dB in HF.

Solidly mounted resonators operated in thickness shear mode based on c-axis oriented AlN films

We fabricated the solidly mounted resonators operated in thickness shear mode using lateral field excitation. The resonators are consisted of the electrodes parallel to the film surface, the c-axis oriented AlN film and the Bragg reflector of SiO 2/AlN. In order to design the electrode frame, the electric field characteristic was calculated by finite element modeling. More than 20 finished devices were tested. The results show that the thickness shear mode wave can be excited by the lateral electric field in the c-axis oriented AlN film. There no obvious longitudinal resonance was found in the frequency responses due to the weak vertical electric field component generated by the parallel electrodes and the high frequency selectivity of the acoustic reflector. The resonators operated in thickness shear mode have resonance frequencies near 2 GHz with the average Q-factor of 520 in air. Importantly for sensors, the immersion into de-ionized water and glycerol liquids still allow for a high Q-factor of 408 and 313, respectively. This resonator shows the potential as mass loading sensors for biochemical application.

Satellite monitoring of anomalous effects in the ionosphere related to the great Wenchuan earthquake of May 12, 2008

In this paper, we present an investigation into plasma density disturbances and electric field perturbations associated with China, Sichuan, Wenchuan earthquake of magnitude M = 7.9 that occurred on May 12, 2008, at 06:28:01 UTC. The DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite was launched on June 29, 2004. The orbit of DEMETER is polar, circular with an altitude of 710 km and its main scientific objective is the study of ionospheric perturbations linked to seismic activity. For satellite orbits near the epicenter region, some ionospheric effects are investigated, which can be considered as possible earthquake precursors. The paper discusses anomalous effects in the ionosphere associated with the Wenchuan earthquake, which cannot be explained by factors of solar-magnetospheric origin. For satellite orbits eight to four days before the main shock, fluctuations in ion density and increase in horizontal and vertical components of electric field are observed near the epicenter. Post-effect is observed too. The observations suggest a coupling between the lithosphere-atmosphere-ionosphere and can be associated with the earthquake growing processes in the lithosphere and troposphere zones above the source. The results of ionospheric anomalous effects are presented and discussed. The results obtained are important because they are observed very near to epicenter.

Electromagnetic scattering by a subwavelength circular hole in a perfect metal plate of finite thickness: matched asymptotic expansion

We present an approach to the problem of electromagnetic scattering by a subwavelength circular hole in a perfect metal plate of finite thickness. The matched asymptotic expansion is employed to solve the scattered fields in the inner and outer regions with respect to the hole position. By use of the dual potentials and Fabrikant’s theory, the solutions are expressed as a combination of spherical functions. In particular, the scattering behavior is illustrated with the near-field quasistatic potentials as well as the far-field radiation patterns. The dipole strengths associated with the subwavelength hole are scaled by the angle of incidence in terms of the vertical electric field and/or horizontal magnetic field components. The effect of the plate thickness is manifest on the attenuation of the dipole strengths associated with the subwavelength hole. For a large thickness, the dipole strengths approach the values for an infinitely deep hole, while for a very small thickness, the results coincide with the Bethe theory.

Distribution of cloud-to-ground lightning electromagnetic pulse fields under the ground

In order to find out the distribution of lightning electromagnetic pulse (LEMP) fields under the ground, the two-dimensional finite-difference time-domain method is used to calculate LEMP under the ground. The distributions of LEMP under the ground are calculated in the cases of different distances from the lightning channel, different ground conductivities, different ground permittivities and different depths. The attenuations of lightning fields in the ground are compared with those of other high-power electromagnetic environments. The calculated results show the following points: the LEMP dramatically attenuates as the distance increases; the attenuation of the electric component is significant when the ground conductivity is reasonably high; the change of ground permittivity mainly causes the change of vertical electric field component, which decreases as the ground permittivity increases; the attenuation of the high frequency electric component increases and that of the low frequency electric component invisibly changes as the depth increases.

Estimation of charge neutralized by negative cloud-to-ground flashes in Catalonia thunderstorms

Charges neutralized by lightning flashes have been usually located and inferred from the quasi-static changes in the vertical component of electric field (Δ E) obtained from multiple synchronized measurement stations. In this paper, the charges neutralized by negative cloud-to-ground (−CG) lightning flashes are located and inferred using single station electric field measurements in combination with total lightning (cloud-to-ground and intra-cloud) data from lightning detection networks in the north-eastern region of Spain. The altitude of the negative charge region in 8 thunderstorms examined here was in the range of 5.8–7.2 km as inferred from temperature soundings. Charge locations are assumed to be in the region where the VHF (Very High Frequency) sources associated with the discharge are located. The quantity of charge neutralized is calculated using a point charge model and the measured vertical component of electric field (Δ E) associated with each flash. The results are compared with those previously obtained from measurements carried out in the NASA Kennedy Space Center (KSC) in Florida. The analysis of 260 −CG flashes from eight thunderstorms reveals a median charge value of −9.7 C with 95% of the values ranging between −4.5 C and −45 C.

Effect of magnetic storms in variations in the atmospheric electric field at midlatitudes

The observations of the variations in the vertical component of the atmospheric electric field (E z ) at Swider midlatitude Poland observatory (geomagnetic latitude 47.8°) under the conditions of fair weather during 14 magnetic storms have been analyzed. The effect of the magnetic storm main phase in the daytime midlatitude variations in E z in the absence of local geomagnetic disturbances has been detected for the first time. Considerable (∼100–300 V m−1) decreases in the electric field strength (E z ) at Swider observatory were observed in daytime simultaneously with the substorm onset in the nighttime sector of auroral latitudes (College observatory). The detected effects indicate that an intensification of the interplanetary electric field during the magnetic storm main phase, the development of magnetospheric substorms, and precipitation of energetic electrons into the nighttime auroral ionosphere can result in considerable disturbances in the midlatitude atmospheric electric field.

A finite-difference time-domain approach for the evaluation of electromagnetic fields radiated by lightning strikes to tall structures

We present an analysis of the electromagnetic fields at very close range from a tower struck by lightning. The electromagnetic fields are evaluated for observation points above, on the surface and below the ground plane characterized by a finite conductivity. The computations are obtained using the Finite-Difference Time-Domain (FDTD) technique, in which the so-called engineering models are incorporated to represent the spatial–temporal distribution of the current along the channel and along the strike object. The approach is tested using a set of simultaneously recorded data published in the literature consisting of the current measured at the top of the Peissenberg tower and the associated electric and magnetic fields and very good agreement has been found. Simulation results are performed for an observation point located 50 m from the base of the channel (or tower, when present) and for three cases, namely (i) a lightning strike to ground, and (ii) a lightning strike to a 168-m tall tower, and (iii) a lightning strike to a 553-m tall tower. The effect of the presence of the tower and the effect of finite ground conductivity on the generated above-ground and underground electromagnetic fields are illustrated and discussed. It is shown that the underground electric fields are markedly affected by the ground conductivity. The underground electric field is predominantly horizontal with a negative polarity. The vertical electric field component is characterized by a bipolar wave-shape. The ground conductivity affects in a lesser degree the magnetic field penetrating into the ground. Above the ground and on the ground surface, the vertical electric field and the azimuthal magnetic field generated by a lightning return stroke initiated at ground level are nearly insensitive to the height of the observation point above ground. For the considered distance range (50 m), they can be computed assuming the ground as a perfectly conducting plane. The magnetic field above ground at such close distance is virtually not affected by the ground conductivity. The presence of a tower results in a significant decrease of the vertical electric field in the immediate vicinity of the tower. Unlike the case of a ground-initiated return stroke, the above-ground vertical electric field associated with a return stroke to tall tower is very much affected by the ground conductivity. Depending on the value of this latter, this component could exhibit an inversion of polarity.

Improving the solution accuracy of thin dielectric approximation with a vertical electric field component

AbstractThe traditional thin dielectric sheet approximation (TDS) method models the electromagnetic scattering by thin dielectric sheet using surface integral equation. In this approximation, only the tangential current within the dielectric sheet is considered, and the vertical component is ignored. This article proposes a method that uses the volume integral equation solution to predict the vertical volume current and hence to improve the overall solution accuracy. The formulation is based on the hybrid surface (SIE) and volume integration equation (VIE) in which, the thin dielectric is modeled with SIE, and the thin layers are modeled by VIE. It is shown that the inclusion of the vertical current component does not increase memory and solution time. Numerical examples will be provided to demonstrate the effectiveness of this approach. © Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1978–1982, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23518

Quasi-static electric fields phenomena in the ionosphere associated with pre- and post earthquake effects

Abstract. To prove a direct relationship between the quasi-static electric field disturbances and seismic activity is a difficult, but actual task of the modern ionosphere physics. This paper presents new results on the processing and analysis of the quasi-static electric field in the upper ionosphere (h=800–900 km) observed from the satellite INTERCOSMOS-BULGARIA-1300 over earthquakes' source regions (seismic data of World Data Center, Denver, Colorado, USA). Present research focuses on three main areas (i) development of methodology of satellite and seismic data selecting, (ii) data processing and observations of the quasi-static electric field (iii) study and accumulation of statistics of possible connection between anomalous vertical electric fields penetrating from the earthquake zone into the ionosphere, and seismic activity. The most appropriate data (for satellite orbits above sources of forthcoming or just happened seismic events) have been selected from more than 250 investigated cases.The increase of about 5-10-15 mV/m in the vertical component of the quasi-static electric field observed by INTERCOSMOS-BULGARIA-1300 during seismic activity over Southern Ocean, Greenland Sea, South-Weat Pacific Ocean, Indian Ocean, Central America, South-East Pacific Ocean, Malay Archipelago regions are presented. These anomalies, as phenomena accompanying the seismogenic process, can be considered eventually as possible pre-, co- (coeval to) and post-earthquake effects in the ionosphere.

Electric field and ion density anomalies in the mid latitude ionosphere: Possible connection with earthquakes?

The problem of earthquake prediction has stimulated the search for a correlation between seismic activity and ionospherical anomalies. We found observational evidence of possible earthquake effects in the near-equatorial and low latitude ionosphere; these ionospheric anomalies have been proposed by Gousheva et al. [Gousheva, M., Glavcheva, R., Danov, D., Angelov P., Hristov, P., Influence of earthquakes on the electric field disturbances in the ionosphere on board of the Intercosmos-Bulgaria-1300 satellite. Compt. Rend. Acad. Bulg. Sci. 58 (8) 911–916, 2005a; Gousheva, M., Glavcheva, R., Danov, D., Angelov, P., Hristov, P., Kirov, B., Georgieva, K., Observation from the Intercosmos-Bulgaria-1300 satellite of anomalies associated with seismic activity. In: Poster Proceeding of 2nd International Conference on Recent Advances in Space Technologies: Space in the Service of Society, RAST ‘2005, June 9–11, Istanbul, Turkey, pp. 119–123, 2005b; Gousheva, M., Glavcheva, R., Danov, D., Angelov, P., Hristov, P., Kirov, B., Georgieva, K., Satellite monitoring of anomalous effects in the ionosphere probably related to strong earthquakes. Adv. Space Res. 37 (4), 660–665, 2006]. This paper presents new results from observations of the quasi-static electric field and ion density on board INTERCOSMOS-BULGARIA-1300 satellite in the mid latitude ionosphere above sources of moderate earthquakes. Data from INTERCOSMOS-BULGARIA-1300 satellite and seismic data (World Data Center, Denver, Colorado, USA) for magnetically quiet and medium quiet days are juxtaposed in time-space domain. For satellite’s orbits in the time period 15.09–01.10.1981 an increase in the horizontal and vertical components of the quasi-static electric field and fluctuations of the ion density are observed over zones of forthcoming seismic events. Some similar post effects are observed too. The emphasis of this paper is put on the anomalies which specify the mid latitude ionosphere. The obtained results contain important information because they confirm our previous results for near-equatorial and low latitude regions.

Peculiar transient events in the Schumann resonance band and their possible explanation

Superimposed on the continuous Schumann resonance (SR) background in the extremely low frequency (ELF) band, transient signals (e.g. bursts) can be observed, which originate from intense lightning discharges occurring at different locations on the globe. From the many transients that were observed at the Astronomical and Geophysical Observatory (AGO) of Comenius University near Modra, western Slovakia, in the vertical electric field component mainly during May and June of 2006, a peculiar group of events could be recognized. According to the waveform analysis, these peculiar events in most cases consist of two overlapping transients with a characteristic time difference of 0.13–0.15 s between the onsets. On the other hand, the spectrum of these peculiar transients showed discernible SR peaks for higher modes as well ( n>7). The same events could be found in the records of the Széchenyi István Geophysical Observatory of the Geodetic and Geophysical Research Institute of the Hungarian Academy of Sciences near Nagycenk, Hungary (NCK). The natural origin of the peculiar events was verified from the NCK data and the source location was determined from the second transient. The results suggest that the two consecutive transients originated in the same thunderstorm. Furthermore, the phase spectrum analysis indicates that the sources have coherently excited the Earth-ionosphere cavity. These findings seem to support the idea that electromagnetic waves orbiting the Earth might trigger lightning discharges. The possibility that electromagnetic waves may trigger discharges was first considered by Nikola Tesla.

Signatures of the day‐night asymmetry of the Earth‐ionosphere cavity in high time resolution Schumann resonance records

High time resolution Schumann resonance (SR) records are analyzed at a midlatitude (Nagycenk, 47.6°N, 16.7°E, Hungary) and a north polar (Hornsund, 77°N, 15.5°E, Spitsbergen) station from the point of view of the day‐night asymmetry of the Earth‐ionosphere cavity. The vertical electric field component, EZ, at Nagycenk in quasi‐minute time resolution exhibits jump‐like increases of SR amplitudes between the local ionospheric and surface sunrise times and sharp decreases between the local surface and ionospheric sunset times. These amplitude variations depend on frequency, increase with increasing mode number, and occur simultaneously in the three SR modes studied here. The duration of the sharp frequency‐dependent amplitude changes is generally less than 30 min. The accurate timing (“clock‐like accuracy”) of these sharp SR amplitude variations of about 12–25% in the local sunrise/sunset periods and their frequency dependence make these changes distinguishable from the amplitude variations related to the lightning source properties and strongly suggest an ionospheric origin for these sharp amplitude variations. The signature of the day‐night asymmetry of the Earth‐ionosphere cavity can also be found at Hornsund in the two short spring and autumn periods with alternating day and night periods every day, in the form of an enhanced day‐night contrast of the SR amplitudes with consistent frequency dependence for the first three SR modes.

Influence of ionization-radiation power on electric effects in the atmospheric boundary layer

We consider the mechanism of fluctuations of the vertical component of near-ground electric field of the atmosphere. We propose the mechanism of appearance of VHF electromagnetic radiation in the atmosphere resulting from rotationally-rotary transitions of dipole quasi-molecules consisting of large hydrated cluster ions. A molecular kinetic model of water vapor condensation on the atmospheric charged drops is developed.