Direct measurements of the Poynting flux associated with convection electric fields in the magnetosphere

2010 ◽  
Vol 115 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
Y. Nishimura ◽  
T. Kikuchi ◽  
A. Shinbori ◽  
J. Wygant ◽  
Y. Tsuji ◽  
...  
Keyword(s):  
Electric Fields ◽  
Poynting Flux ◽  
Direct Measurements

scholarly journals High-latitude poynting flux from combined Iridium and SuperDARN data

2004 ◽  
Vol 22 (8) ◽  
pp. 2861-2875 ◽  
Author(s):  
C. L. Waters ◽  
B. J. Anderson ◽  
R. A. Greenwald ◽  
R. J. Barnes ◽  
J. M. Ruohoniemi
Keyword(s):  
Electric Fields ◽  
Energy Flux ◽  
High Latitude ◽  
Electromagnetic Energy ◽  
Total Power ◽  
Data Sets ◽  
Poynting Flux ◽  
Magnetic Perturbations ◽  
Magnetometer Data ◽  
A New Technique

Abstract. Field-aligned currents convey stress between the magnetosphere and ionosphere, and the associated low altitude magnetic and electric fields reflect the flow of electromagnetic energy to the polar ionosphere. We introduce a new technique to measure the global distribution of high latitude Poynting flux, S||, by combining electric field estimates from the Super Dual Auroral Radar Network (SuperDARN) with magnetic perturbations derived using magnetometer data from the Iridium satellite constellation. Spherical harmonic methods are used to merge the data sets and calculate S|| for any magnetic local time (MLT) from the pole to 60° magnetic latitude (MLAT). The effective spatial resolutions are 2° MLAT, 2h MLT, and the time resolution is about one hour due to the telemetry rate of the Iridium magnetometer data. The technique allows for the assessment of high-latitude net S|| and its spatial distribution on one hour time scales with two key advantages: (1) it yields the net S|| including the contribution of neutral winds; and (2) the results are obtained without recourse to estimates of ionosphere conductivity. We present two examples, 23 November 1999, 14:00-15:00 UT, and 11 March 2000, 16:00-17:00 UT, to test the accuracy of the technique and to illustrate the distributions of S|| that it gives. Comparisons with in-situ S|| estimates from DMSP satellites show agreement to a few mW/m2 and in the locations of S|| enhancements to within the technique's resolution. The total electromagnetic energy flux was 50GW for these events. At auroral latitudes, S|| tends to maximize in the morning and afternoon in regions less than 5° in MLAT by two hours in MLT having S||=10 to 20mW/m2 and total power up to 10GW. The power poleward of the Region 1 currents is about one-third of the total power, indicating significant energy flux over the polar cap.

scholarly journals Statistics of Joule heating in the auroral zone and polar cap using Astrid-2 satellite Poynting flux

2004 ◽  
Vol 22 (12) ◽  
pp. 4133-4142 ◽  
Author(s):  
A. Olsson ◽  
P. Janhunen ◽  
T. Karlsson ◽  
N. Ivchenko ◽  
L. G. Blomberg
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Joule Heating ◽  
Building Blocks ◽  
Auroral Zone ◽  
Power Budget ◽  
Flux Method ◽  
Poynting Flux ◽  
Background Magnetic Field ◽  
Magnetospheric Configuration And Dynamics

Abstract. We make a statistical study of ionospheric Joule heating with the Poynting flux method using six months of Astrid-2/EMMA electric and magnetic field data during 1999 (solar maximum year). For the background magnetic field we use the IGRF model. Our results are in agreement with earlier statistical satellite studies using both the ΣPE2 method and the Poynting flux method. We present a rather comprehensive set of fitted Joule heating formulas expressing the Joule heating in given magnetic local time (MLT) and invariant latitude (ILAT) range under given solar illumination conditions as a function of the Kp index, the AE index, the Akasofu epsilon parameter and the solar wind kinetic energy flux. The study thus provides improved and more detailed estimates of the statistical Joule heating. Such estimates are necessary building blocks for future quantitative studies of the power budget in the magnetosphere and in the nightside auroral region. Key words. Ionosphere (electric fields and currents; ionosphere-magnetosphere interactions) – Magnetospheric physics (magnetospheric configuration and dynamics)

Direct measurements of dislocation charges in Ca2+‐doped KC1 by using large electric fields

1984 ◽  
Vol 49 (3) ◽  
pp. 395-407 ◽  
Author(s):  
Toshihiko Kataoka ◽  
Luigi Colombo ◽  
J. C. M. Li
Keyword(s):  
Electric Fields ◽  
Direct Measurements

scholarly journals Direct Measurements of Electric Fields in Weak Hydrogen Bonds

2012 ◽  
Vol 102 (3) ◽  
pp. 269a ◽  
Author(s):  
Miguel Saggu ◽  
Nicholas M. Levinson ◽  
Steven G. Boxer
Keyword(s):  
Hydrogen Bonds ◽  
Electric Fields ◽  
Direct Measurements ◽  
Weak Hydrogen Bonds

scholarly journals A mechanism for ageing in a deeply supercooled molecular glass

2021 ◽  
Author(s):  
Andrew Cassidy ◽  
Mads Ry Vogel Jørgensen ◽  
Artur Glavic ◽  
Valeria Lauter ◽  
Oksana Plekan ◽  
...  
Keyword(s):  
Electric Fields ◽  
Energy Barrier ◽  
Methyl Formate ◽  
Secondary Relaxation ◽  
Molecular Glass ◽  
Direct Measurements ◽  
Deposited Films

Measurements of the decay of electric fields, formed spontaneously within vapour-deposited films of cis-methyl formate, provide the first direct measurements of the energy barrier to secondary relaxation mechanisms in a...

scholarly journals Noninvasive Measurement of Conductivity Anisotropy at Larmor Frequency Using MRI

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Joonsung Lee ◽  
Yizhuang Song ◽  
Narae Choi ◽  
Sungmin Cho ◽  
Jin Keun Seo ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Current Density ◽  
Partial Information ◽  
Larmor Frequency ◽  
Biological Tissues ◽  
Conductivity Tensor ◽  
Conductivity Anisotropy ◽  
Circulating Current ◽  
Direct Measurements

Anisotropic electrical properties can be found in biological tissues such as muscles and nerves. Conductivity tensor is a simplified model to express the effective electrical anisotropic information and depends on the imaging resolution. The determination of the conductivity tensor should be based on Ohm's law. In other words, the measurement of partial information of current density and the electric fields should be made. Since the direct measurements of the electric field and the current density are difficult, we use MRI to measure their partial information such as B1 map; it measures circulating current density and circulating electric field. In this work, the ratio of the two circulating fields, termed circulating admittivity, is proposed as measures of the conductivity anisotropy at Larmor frequency. Given eigenvectors of the conductivity tensor, quantitative measurement of the eigenvalues can be achieved from circulating admittivity for special tissue models. Without eigenvectors, qualitative information of anisotropy still can be acquired from circulating admittivity. The limitation of the circulating admittivity is that at least two components of the magnetic fields should be measured to capture anisotropic information.

scholarly journals Direct Measurements of Electric Fields in Weak OH···π Hydrogen Bonds

2011 ◽  
Vol 133 (43) ◽  
pp. 17414-17419 ◽  
Author(s):  
Miguel Saggu ◽  
Nicholas M. Levinson ◽  
Steven G. Boxer
Keyword(s):  
Hydrogen Bonds ◽  
Electric Fields ◽  
Direct Measurements
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