scholarly journals Ionospheric quasi-static electric field anomalies during seismic activity in August–September 1981

2009 ◽  
Vol 9 (1) ◽  
pp. 3-15 ◽  
Author(s):  
M. Gousheva ◽  
D. Danov ◽  
P. Hristov ◽  
M. Matova
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Research Work ◽  
Vertical Component ◽  
Plate Tectonic ◽  
Static Electric Field ◽  
Earthquake Sources ◽  
Source Regions ◽  
Vertical Electric Field ◽  
Upper Ionosphere

Abstract. The paper proposes new results, analyses and information for the plate tectonic situation in the processing of INTERCOSMOS-BULGARIA-1300 satellite data about anomalies of the quasi-static electric field in the upper ionosphere over activated earthquake source regions at different latitudes. The earthquake catalogue is made on the basis of information from the United State Geological Survey (USGS) website. The disturbances in ionospheric quasi-static electric fields are recorded by IESP-1 instrument aboard the INTERCOSMOS-BULGARIA-1300 satellite and they are compared with significant seismic events from the period 14 August–20 September 1981 in magnetically very quiet, quiet and medium quiet days. The main tectonic characteristics of the seismically activated territories are also taken in account. The main goal of the above research work is to enlarge the research of possible connections between anomalous vertical electric field penetrations into the ionosphere and the earthquake manifestations, also to propose tectonic arguments for the observed phenomena. The studies are represented in four main blocks: (i) previous studies of similar problems, (ii) selection of satellite, seismic and plate tectonic data, (iii) data processing with new specialized software and observations of the quasi-static electric field and (iiii) summary, comparison of new with previous results in our studies and conclusion. We establish the high informativity of the vertical component Ez of the quasi-static electric field in the upper ionosphere according observations by INTERCOSMOS-BULGARIA-1300 that are placed above considerably activated earthquake sources. This component shows an increase of about 2–10 mV/m above sources, situated on mobile structures of the plates. The paper discusses the observed effects. It is represented also a statistical study of ionospheric effects 5–15 days before and 5–15 days after the earthquakes with magnitude M 4.8–7.9.

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

2008 ◽  
Vol 8 (1) ◽  
pp. 101-107 ◽  
Author(s):  
M. Gousheva ◽  
D. Danov ◽  
P. Hristov ◽  
M. Matova
Keyword(s):  
Pacific Ocean ◽  
Electric Field ◽  
Electric Fields ◽  
Seismic Data ◽  
Seismic Activity ◽  
Vertical Component ◽  
Satellite Orbits ◽  
Static Electric Field ◽  
Earthquake Zone ◽  
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.

Fluid Mixing Control Inside a Y-Shaped Microchannel by Using Electrokinetic Instability

2007 ◽  
Author(s):  
Zheyan Jin ◽  
Hui Hu
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Fluid Mixing ◽  
Critical Voltage ◽  
Mixing Efficiency ◽  
Mixing Process ◽  
Static Electric Field ◽  
Electrokinetic Instability ◽  
Mixing Control ◽  
Static Electric Fields

An experimental study was conducted to further our understanding about the fundamental physics of electrokinetic instability (EKI) and to explore the effectiveness to enhance fluid mixing inside a Y-shaped microchannel by manipulating convective EKI waves. The dependence of the critical voltage of applied static electric field to trig EKI to generate convective EKI waves on the conductivity ratio of the two adjacent streams was quantified at first. The effect of the strength of the applied static electric field on the evolution of the convective EKI waves and fluid mixing process were assessed in terms of scalar concentration fields, shedding frequency of the convective EKI waves and scalar mixing efficiency. The effectiveness of manipulating the convective EKI waves by introducing alternative electric perturbations to the applied static electric fields was also explored for the further enhancement of the fluid mixing process inside the Y-shaped microchannel.

On modeling airborne very low‐frequency measurements

Geophysics ◽  
1989 ◽  
Vol 54 (12) ◽  
pp. 1596-1606 ◽  
Author(s):  
Ari Poikonen ◽  
Ilkka Suppala
Keyword(s):  
Plane Wave ◽  
Electric Field ◽  
Numerical Models ◽  
Vertical Component ◽  
Low Frequency ◽  
Primary Field ◽  
Vertical Electric Field ◽  
Inhomogeneous Plane ◽  
Inhomogeneous Plane Wave ◽  
Attenuation Characteristics

Numerical models employed in ground VLF modeling use a normally incident (homogeneous) plane wave as a primary field. We show that these models are not directly applicable to modeling the impedance and wavetilt in the air, quantities needed in the interpretation of airborne VLF resistivity measurements. Instead, the primary field must be replaced by an inhomogeneous plane wave incident on the ground at an angle close to 90 degrees in order to provide the correct behavior of the apparent resistivities in the air. VLF magnetic polarization parameters, however, can be modeled in the air using the normally incident plane wave as a primary field. We also show that the plane‐wave analysis provides the same attenuation characteristics for the wavetilt in the air that is predicted by the Norton’s surface wave obtained by using the vertical electric dipole as a source. Use of the inhomogeneous plane wave introduces the vertical component of the electric field in the model. A 2‐D modeling technique based on the network solution is used to demonstrate the effects of the vertical electric field in the H‐polarization case. The vertical electric field generates charge distributions on the horizontal boundaries of conductors. In the case of a vertical sheet‐like conductor, these charges cause a slight asymmetry in apparent‐resistivity anomalies. Attenuation characteristics of various VLF anomalies with altitude are also presented. The H‐polarization anomalies attenuate much more rapidly in the air than those for E‐polarization due to the difference in the dominating source of EM fields in each polarization.

scholarly journals Storm enhanced density: magnetic conjugacy effects

2007 ◽  
Vol 25 (8) ◽  
pp. 1791-1799 ◽  
Author(s):  
J. C. Foster ◽  
W. Rideout
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Ionospheric Disturbance ◽  
Polar Regions ◽  
The North ◽  
Polar Caps ◽  
Source Regions ◽  
Field Lines ◽  
Magnetic Conjugacy ◽  
Early Phases

Abstract. In the early phases of a geomagnetic storm, the low and mid-latitude ionosphere are greatly perturbed. Large SAPS electric fields map earthward from the perturbed ring current overlapping and eroding the outer plasmasphere and mid-latitude ionosphere, drawing out extended plumes of storm enhanced density (SED). We use combined satellite and ground-based observations to investigate the degree of magnetic conjugacy associated with specific features of the stormtime ionospheric perturbation. We find that many ionospheric disturbance features exhibit degrees of magnetic conjugacy and simultaneity which implicate the workings of electric fields. TEC enhancements on inner-magnetospheric field lines at the base of the SED plumes exhibit localized and longitude-dependent features which are not strictly magnetic conjugate. The SED plumes streaming away from these source regions closely follow magnetic conjugate paths. SED plumes can be used as a tracer of the location and strength of disturbance electric fields. The SED streams of cold plasma from lower latitudes enter the polar caps near noon, forming conjugate tongues of ionization over the polar regions. SED plumes exhibit close magnetic conjugacy, confirming that SED is a convection electric field dominated effect. Several conclusions are reached: 1) The SED plume occurs in magnetically-conjugate regions in both hemispheres. 2) The position of the sharp poleward edge of the SED plume is closely conjugate. 3) The SAPS electric field is observed in magnetically conjugate regions (SAPS channel). 4) The strong TEC enhancement at the base of the SED plume in the north American sector is more extensive than in its magnetic conjugate region. 5) The entry of the SED plume into the polar cap near noon, forming the polar tongue of ionization (TOI), is seen in both hemispheres in magnetically-conjugate regions.

TWO-PHOTON-ABSORPTION SPECTRA OF QUANTUM-WELL EXCITONS IN STATIC ELECTRIC FIELDS

1991 ◽  
Vol 05 (17) ◽  
pp. 1133-1138
Author(s):  
KAZUHITO FUJII ◽  
AKIRA SHIMIZU ◽  
JOHAN BERGQUIST ◽  
SOTOMITSU IKEDA ◽  
TAKESHI SAWADA
Keyword(s):  
Electric Field ◽  
Quantum Well ◽  
Absorption Spectra ◽  
Electric Fields ◽  
Band Gap Energy ◽  
Photon Absorption ◽  
Static Electric Field ◽  
Quantum Well Structures ◽  
Two Photon Absorption ◽  
Two Photon

We have measured two-photon-absorption spectra of GaAs/Al 0.4 Ga 0.6 As quantum-well structures in a static electric field for photon energies near half the band gap energy, and found drastic field-induced-changes in the spectra. The two-photon-absorption peak at half the energy of the lowest light-hole exciton is induced by the static electric field normal to the quantum well layers, in agreement with a theory that takes account of quasi-two-dimensional exciton effects. With increasing the electric field, however, this peak grows more drastically than the theoretical prediction, and it approaches a large value predicted by another simplified theory based on a two-level model.

scholarly journals Body Water-Mediated Conductivity Actualizes the Insect-Control Functions of Electric Fields in Houseflies

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 561 ◽  
Author(s):  
Yoshihiro Takikawa ◽  
Takeshi Takami ◽  
Koji Kakutani
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Arc Discharge ◽  
Body Water ◽  
The Body ◽  
Static Electric Field ◽  
Free Electrons ◽  
Water Conductivity ◽  
Control Functions ◽  
Negative Pole

In the present study, the relationship between body water loss and conductivity was examined in adult houseflies (Musca domestica). The events an insect experiences in an electric field are caused by the conductive nature of the insect body (i.e., movement of electricity within or its release from the insect). After houseflies were dehydrated, rehydrated, refrigerated, and frozen and thawed, they were placed in static and dynamic electric fields. Untreated houseflies were deprived of their free electrons to become positively charged and then attracted to the insulated negative pole in the static electric field and were exposed to corona and arc discharge from non-insulated negative pole in the dynamic electric field. There was no current in the bodies of dehydrated and frozen flies; hence, there was no attractive force or discharge exposure. In the remaining insects, the results were identical to those in the untreated control insects. These results indicated that the reduction of body water conductivity inhibited the release of electricity from the body in the static electric field and the discharge-mediated current flow through the body in the dynamic electric field. The insect was affected by the electric fields because of its conductivity mediated by body water.

scholarly journals Seafloor massive sulphide exploration using deep-towed controlled source electromagnetics: Navigational uncertainties

2019 ◽  
Author(s):  
Romina A S Gehrmann ◽  
Amir Haroon ◽  
McKinley Morton ◽  
Axel T Djanni ◽  
Timothy A Minshull
Keyword(s):  
Electric Field ◽  
Error Estimation ◽  
Electric Fields ◽  
Final Model ◽  
Controlled Source ◽  
Precise Knowledge ◽  
Geophysical Surveys ◽  
Vertical Electric Field ◽  
Irregular Motion ◽  
Data Error

SUMMARY Deep-towed geophysical surveys require precise knowledge of navigational parameters such as instrument position and orientation because navigational uncertainties reflect in the data and therefore in the inferred geophysical properties of the sub-seafloor. We address this issue for the case of electrical conductivity inferred from controlled source electromagnetic data. We show that the data error is laterally variable due to irregular motion during deep towing, but also due to lateral variations in conductivity, including those resulting from topography. To address this variability and quantify the data error prior to inversion, we propose a two-dimensional perturbation study. Our workflow enables stable and geologically reliable results for multi-component and multi-frequency inversions. An error estimation workflow is presented, which comprises the assessment of navigational uncertainties, perturbation of navigational parameters, and forward modelling of electric field amplitudes for a homogeneous and then a heterogeneous sub-seafloor conductivity model. Some navigational uncertainties are estimated from variations of direct measurements. Other navigational parameters required for inversion are derived from the measured quantities and their error is calculated by means of error propagation. Some navigational parameters show direct correlation with the measured electric fields. For example, the antenna dip correlates with the vertical electric field and the depth correlates with the horizontal electric field. For the perturbation study each standard deviation is added to the navigational parameters. Forward models are run for each perturbation. Amplitude deviations are summed in quadrature with the stacking error for a total, laterally varying, data error. The error estimation is repeated for a heterogeneous sub-seafloor model due to the large conductivity range (several orders of magnitude), which affects the forward model. The approach enables us to utilize data from several components (multiple electric fields, frequencies and receivers) in the inversion to constrain the final model and reduce ambiguity. The final model is geologically reasonable, in this case enabling the identification of conductive metal sulphide deposits on the seafloor.

Effects of Lightning Current and Ground Conductivity on the Values of Vertical Electric Fields

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
M. Izadi ◽  
M. Z. A. Ab Kadir ◽  
M. Hajikhani ◽  
N. Rameli
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Lightning Current ◽  
Lightning Channel ◽  
Vertical Electric Field ◽  
The Relationship ◽  
Ground Conductivity

In this paper, the relationship between current front time and front time of vertical electric field due to lightning channel at non perfect ground is considered. Results showed that the peak of simulated vertical electric fields under non perfect ground conductivity condition is decreased compared to the corresponding field at perfect ground while the front time of field is increased at non perfect case compared to the perfect one. Likewise, the effect of ground conductivity on the peak and front time of simulated vertical electric field is considered and the results are discussed accordingly.

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

2000 ◽  
Vol 18 (5) ◽  
pp. 523-531 ◽  
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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