scholarly journals Electrojet estimates from mesospheric magnetic field measurements

2021 ◽  
Author(s):  
Karl Laundal ◽  
Jeng-Hwa Yee ◽  
Jesper Gjerloev ◽  
Heikki Vanhamäki ◽  
Jone Reistad ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Measurements ◽  
Low Earth Orbit ◽  
Measurement Technology ◽  
Magnetic Field Sensors ◽  
Spatiotemporal Characteristics ◽  
Spatial Coverage ◽  
Magnetic Field Measurements ◽  
The Magnetic Field ◽  
Current Representation

<p>The auroral electrojet is traditionally measured remotely with magnetometers on ground or in low Earth orbit (LEO). The sparse spatial coverage of measurements, combined with a vertical distance (~100 km to ground and typically >300 km to LEO satellites) means that smaller scale sizes cannot be detected.  Because of this, our understanding of the spatiotemporal characteristics of the electrojet is incomplete. Recent advances in measurement technology allow us to overcome these limitations by multi-point remote detections of the magnetic field in the mesosphere, very close to the electrojet. We present a theoretical prediction of the magnitude of these disturbances, inferred from the spatiotemporal characteristics of magnetic field-aligned currents. We further discuss how the Electrojet Zeeman Imaging Explorer (EZIE) satellites that will carry Zeeman magnetic field sensors will be used to essentially image the equivalent current at unprecedented spatial resolution.  The electrojet imaging is demonstrated by combining carefully simulated measurements with a spherical elementary current representation using a novel inversion scheme.  This new capability will allow us to finally resolve long-standing controversies such as – what is the substorm current wedge configuration?</p>

scholarly journals Electrojet estimates from mesospheric magnetic field measurements

2020 ◽  
Author(s):  
Karl Laundal ◽  
Jesper Gjerloev ◽  
Sam Yee ◽  
Slava Merkin ◽  
Heikki Vanhamäki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Measurements ◽  
Low Earth Orbit ◽  
Measurement Technology ◽  
Earth Orbit ◽  
Long Distance ◽  
Small Satellites ◽  
Spatiotemporal Characteristics ◽  
Magnetic Field Measurements ◽  
The Magnetic Field

<p>The auroral electrojet is traditionally measured remotely with magnetometers on ground or in low Earth orbit. The long distance, more than 100 km, means that smaller scale sizes are not detected. Because of this, the spatiotemporal characteristics of the electrojet are not known. Recent advances in measurement technology give hope of remote detections of the magnetic field in the mesosphere, very close to the electrojet. We present a prediction of the magnitude of these disturbances, inferred from the spatiotemporal characteristics of magnetic field-aligned currents. We also discuss how a constellation of small satellites carrying the Microwave Electrojet Magnetogram (MEM) instrument (Yee et al., 2020), could be used to essentially image the equivalent current at unprecedented spatial resolution. </p>

scholarly journals The fluxgate magnetometer of the Low Orbit Pearl Satellites (LOPS): overview of in-flight performance and initial results

2021 ◽  
Vol 10 (2) ◽  
pp. 227-243
Author(s):  
Ye Zhu ◽  
Aimin Du ◽  
Hao Luo ◽  
Donghai Qiao ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current System ◽  
Field Measurements ◽  
Stray Field ◽  
Fluxgate Magnetometer ◽  
General Description ◽  
Flight Performance ◽  
Spatial Coverage ◽  
Magnetic Field Measurements ◽  
Initial Results

Abstract. The Low Orbit Pearl Satellite series consists of six constellations, with each constellation consisting of three identical microsatellites that line up just like a string of pearls. The first constellation of three satellites were launched on 29 September 2017, with an inclination of ∼ 35.5∘ and ∼ 600 km altitude. Each satellite is equipped with three identical fluxgate magnetometers that measure the in situ magnetic field and its low-frequency fluctuations in the Earth's low-altitude orbit. The triple sensor configuration enables separation of stray field effects generated by the spacecraft from the ambient magnetic field (e.g., Zhang et al., 2006). This paper gives a general description of the magnetometer including the instrument design, calibration before launch, in-flight calibration, in-flight performance, and initial results. Unprecedented spatial coverage resolution of the magnetic field measurements allow for the investigation of the dynamic processes and electric currents of the ionosphere and magnetosphere, especially for the ring current and equatorial electrojet during both quiet geomagnetic conditions and storms. Magnetic field measurements from LOPS could be important for studying the method to separate their contributions of the Magnetosphere-Ionosphere (M-I) current system.

scholarly journals Development of Space Magnetometers in Austria

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 1104
Author(s):  
Werner Magnes ◽  
Roland Lammegger ◽  
Martin Agú ◽  
Christoph Amtmann ◽  
Özer Aydogar ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Field Measurements ◽  
Fundamental Information ◽  
Magnetic Field Measurements ◽  
The Magnetic Field

With spaceborne magnetic field measurements it is possible to investigate the interior of planets,moons and asteroids which have either an intrinsic or a crustal magnetic field. Furthermore, preciseknowledge of the magnetic field is essential to derive fundamental information about theenvironment surrounding different bodies in the solar system as well as to explore the interplanetaryspace. [...]

scholarly journals Measurements of the magnetic field in WD 1658+441

2013 ◽  
Vol 9 (S302) ◽  
pp. 402-403
Author(s):  
J. Ramírez Vélez ◽  
D. Hiriart ◽  
G. Valyavin ◽  
J. Valdez ◽  
F. Quiroz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
White Dwarf ◽  
Longitudinal Magnetic Field ◽  
Field Measurements ◽  
Measured Variable ◽  
Preliminary Results ◽  
San Pedro ◽  
Magnetic Field Measurements ◽  
Object Of Study ◽  
The Magnetic Field

AbstractWe present the preliminary results of the measurements of longitudinal magnetic field of the massive white dwarf 1658+441. This star have an hydrogen pure atmosphere (e.g. Dupuis & Chayer, 2003). We have observed the target in a total of 18 hrs during 3 consecutive nights in June 2010 and one more in May 2011. The data was acquired with a prototypical spectropolarimeter at the San Pedro Martir Telescope in Mexico. We have tested the magnetic field measurements with our instrument using the famous Babcock's star obtaining consistent results with previous studies. For our object of study, the WD 1658+441, we have measured variable intensities of the longitudinal magnetic field of Blong = 720 kG that oscillates with an amplitude of 130 kG.

scholarly journals How many solar wind data are sufficient for accurate fluxgate magnetometer offset determinations?

2019 ◽  
Vol 8 (2) ◽  
pp. 285-291 ◽  
Author(s):  
Ferdinand Plaschke
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Wind Data ◽  
Fluxgate Magnetometer ◽  
Time Intervals ◽  
Sensor Position ◽  
Magnetic Field Measurements ◽  
Wind Measurements ◽  
The Magnetic Field

Abstract. Accurate magnetic field measurements by fluxgate magnetometers onboard spacecraft require ground and regular in-flight calibration activities. Therewith, the parameters of a coupling matrix and an offset vector are adjusted; they are needed to transform raw magnetometer outputs into calibrated magnetic field measurements. The components of the offset vector are typically determined by analyzing Alfvénic fluctuations in the solar wind if solar wind measurements are available. These are characterized by changes in the field components, while the magnetic field modulus stays constant. In this paper, the following question is answered: how many solar wind data are sufficient for accurate fluxgate magnetometer offset determinations? It is found that approximately 40 h of solar wind data are sufficient to achieve offset accuracies of 0.2 nT, and about 20 h suffice for accuracies of 0.3 nT or better if the magnetometer offsets do not drift within these time intervals and if the spacecraft fields do not vary at the sensor position. Offset determinations with uncertainties lower than 0.1 nT, however, would require at least hundreds of hours of solar wind data.

scholarly journals Magnetohydrostatic modeling of AR11768 based on a SUNRISE/IMaX vector magnetogram

2020 ◽  
Vol 640 ◽  
pp. A103 ◽  
Author(s):  
X. Zhu ◽  
T. Wiegelmann ◽  
S K. Solanki
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Field Measurements ◽  
Plasma Pressure ◽  
Photospheric Magnetic Field ◽  
Solar Photosphere ◽  
Free Layer ◽  
Lower Boundary Condition ◽  
Magnetic Field Measurements ◽  
The Magnetic Field

Context. High-resolution magnetic field measurements are routinely only done in the solar photosphere. Higher layers, such as the chromosphere and corona, can be modeled by extrapolating these photospheric magnetic field vectors upward. In the solar corona, plasma forces can be neglected and the Lorentz force vanishes. This is not the case in the upper photosphere and chromosphere where magnetic and nonmagnetic forces are equally important. One way to deal with this problem is to compute the plasma and magnetic field self-consistently, in lowest order with a magnetohydrostatic (MHS) model. The non-force-free layer is rather thin and MHS models require high-resolution photospheric magnetic field measurements as the lower boundary condition. Aims. We aim to derive the magnetic field, plasma pressure, and density of AR11768 by applying the newly developed extrapolation technique to the SUNRISE/IMaX data embedded in SDO/HMI magnetogram. Methods. We used an optimization method for the MHS modeling. The initial conditions consist of a nonlinear force-free field (NLFFF) and a gravity-stratified atmosphere. During the optimization procedure, the magnetic field, plasma pressure, and density are computed self-consistently. Results. In the non-force-free layer, which is spatially resolved by the new code, Lorentz forces are effectively balanced by the gas pressure gradient force and gravity force. The pressure and density are depleted in strong field regions, which is consistent with observations. Denser plasma, however, is also observed at some parts of the active region edges. In the chromosphere, the fibril-like plasma structures trace the magnetic field nicely. Bright points in SUNRISE/SuFI 3000 Å images are often accompanied by the plasma pressure and electric current concentrations. In addition, the average of angle between MHS field lines and the selected chromospheric fibrils is 11.8°, which is smaller than those computed from the NLFFF model (15.7°) and linear MHS model (20.9°). This indicates that the MHS solution provides a better representation of the magnetic field in the chromosphere.

scholarly journals High Resolution Magnetic Field Measurements in the Sunspot Photosphere

1993 ◽  
Vol 141 ◽  
pp. 11-19
Author(s):  
Axel Hofmann ◽  
Wolfgang Schmidt ◽  
Horst Balthasar ◽  
Theodore T. Tarbell ◽  
Zoe A. Frank
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Field Strength ◽  
Spectral Resolution ◽  
Field Measurements ◽  
Brightness Variation ◽  
Longitudinal Component ◽  
Azimuthal Variation ◽  
Magnetic Field Measurements ◽  
The Magnetic Field

AbstractWe analysed calibrated Stokes V magnetograms and simultaneously measured Stokes I spectra of high spatial and spectral resolution taken in a medium sized sunspot. We found a clear (anti-) correlation between the brightness variation of penumbral structures and the longitudinal component (B*cosγ) of the magnetic field. No azimuthal variation of the amount of the magnetic field strength (B) was observed across dark and bright structures. There the field is more vertical in bright filaments compared to dark ones.

Strong magnetic field of the peculiar red supergiant VY Canis Majoris

2017 ◽  
Vol 13 (S336) ◽  
pp. 391-392
Author(s):  
Hiroko Shinnaga ◽  
Mark J. Claussen ◽  
Satoshi Yamamoto ◽  
Shimojo Masumi
Keyword(s):  
Magnetic Field ◽  
Stellar Evolution ◽  
Field Measurements ◽  
Circumstellar Envelope ◽  
Magnetic Field Measurements ◽  
High Degree ◽  
The Magnetic Field ◽  
Very High ◽  
Measured Magnetic Field ◽  
Field Strengths

AbstractWe report on magnetic field measurements associated with the well-known extreme red supergiant (RSG), VY Canis Majoris (VY CMa). We measured both linear and circular polarization of the SiO v = 0, J = 1 − 0 transition using a sensitive radio interferometer. The measured magnetic field strengths are surprisingly high. A lower limit for the field strength is expected to be at least ~ 10 Gauss based on the high degree of linear polarization. Since the field strengths are very high, the magnetic field must be a key element in understanding the stellar evolution of VY CMa as well as the dynamical and chemical evolution of the complex circumstellar envelope of the star.

Sign in / Sign up

Export Citation Format

Share Document