Magneto Tail Research Articles

Magnetic field dynamics and noise analysis for space-based GW detector in far-earth orbits: A hybrid modeling approach

TianQin (TQ) mission, the sole proposed gravitational wave detection project in geocentric orbit at an altitude of approximately 105 km, traverses diverse geomagnetic regions. This paper employs a hybrid model to simulate the ambient magnetic field along the TQ orbit, investigating magnetically-induced acceleration noise under varying satellite-sun angles (SSA) and solar activity levels. The highest noise level, approximately 10−16ms−2Hz−1/2, occurs during transregional periods between the magnetosheath (MSH) and magnetotail (MTL). Noise within the MSH region is an order of magnitude lower than the former, with the MTL region exhibiting the lowest levels, although geomagnetic storms can equalize noise in both regions. Statistical analysis indicates that noise in the MTL region correlates with SSA and solar wind dynamic pressure, displaying a spectral characteristic of f−1.03±0.075, while the MSH region shows a Kolmogorov turbulence spectrum near the flank and f−0.5 at the subsolar region.

Selection index for Duroc pigs based on average daily gain, feed conversion ratio, and intramuscular fat content

This study was conducted to compare the genetic gain per sow per year of Duroc pigs in twelve scenarios. These scenarios were based on the number of traits used such as average daily gain (ADG), feed conversion ratio (FCR), intramuscular fat content (IMF) and were also based on the number of records of phenotype for these traits from the individual animal and its relatives. The values of all relevant genetic and economic parameters were selected from the literature and applied to the magnetotail (MT) index model to calculate the index selection accuracy and response per trait. Genetic gain per sow per year was calculated based on a farm with 400 Duroc sows. The results showed that the economic value of FCR was much larger than the economic value of ADG and IMF. The selection response in units of ADG was higher when using phenotypes measured using ADG and FCR only while selection response per unit of IMF was the opposite. The economic weight of the response for IMF using three traits (ADG, FCR, and IMF) information was doubled when using ADG and FCR trait information. The standard deviation (SD) index and genetic gain per year when using information from the three traits were higher than those when using information from ADG and FCR. Within the same number of traits measured, the genetic gain per sow per year was highest at $568.05 when using information of the three traits from the individual animal’s phenotype and their progeny. It was the lowest at $473.06 when using ADG and FCR information from only the animal itself.

Investigating Time Volatility Magnetic Field of the Jovian Moon: Callisto Using Magnetometer Sensor

The dynamic structure of the magnetosphere present in the Jovian environment can be explored by detecting magnetic field of the Jovian moon. The present study provides the evidence of magnetic field variation in the Jovian moon (Callisto). The raw data of magnetic field (.lbl format) obtained from planetary plasma interactions node, at NASA’s portal has been used. Magnetic field vector and time series data were used to determine the magnetic field of the Callisto. Magnetic variation in the moon was assessed using contour plots. MATLAB has been used to generate the time series magnetic graphs of the Callisto moon. Findings revealed that magnetic field varied with changes in time in Callisto. Reverse swept in the magnetic field was observed towards the magneto tail of Jupiter. The methodology adopted in this study can be extended to assess the magnetic field of other Jovian moons also.

Detailed Investigation of a Moving Solar Burst Type IV Radio Emission in on Broadband Frequency

The moving type IV burst component of the solar radio region from 260-380 MHz observed using the CALLISTO spectrometer is discussed in detail. We used the Compound Astronomical Low Cost Low Frequency Spectrometer Transportable Observatory (CALLISTO) system connected to the Log Periodic Dipole Antenna (LPDA) at the National Space Centre, Selangor located (3.0833333°N 101.5333333°E) on 22nd February 2012. It is found that a strong burst that caused by extraordinary solar flares are due to magnetic reconnection effect potentially induced in the near-Earth magneto tail. From our observation the indication of signal potentially drives Coronal Mass Ejections (CMEs). We also compare our results with the Geostationary Operational Environmental Satellites (GOES) data. From our analysis, one possible reason behind the formation of this very complex long duration of this loop is the magnetic reconnection and disruption of the loops which is observed during flare maximum. The Active Region, AR 1429 active region was a site of several intense in several days. From the results, it showed that the burst is formed from the explosion of M-class solar flare which can be observed at 412UT. As a conclusion, a good agreement was reached and we believe that Sun’s activities are more active to pursuit the solar maximum cycle.

Detailed Investigation of a Moving Solar Burst Type IV Radio Emission in on Broadband Frequency

The moving type IV burst component of the solar radio region from 260-380 MHz observed using the CALLISTO spectrometer is discussed in detail. We used the Compound Astronomical Low Cost Low Frequency Spectrometer Transportable Observatory (CALLISTO) system connected to the Log Periodic Dipole Antenna (LPDA) at the National Space Centre, Selangor located (3.0833333°N 101.5333333°E) on 22nd February 2012. It is found that a strong burst that caused by extraordinary solar flares are due to magnetic reconnection effect potentially induced in the near-Earth magneto tail. From our observation the indication of signal potentially drives Coronal Mass Ejections (CMEs). We also compare our results with the Geostationary Operational Environmental Satellites (GOES) data. From our analysis, one possible reason behind the formation of this very complex long duration of this loop is the magnetic reconnection and disruption of the loops which is observed during flare maximum. The Active Region, AR 1429 active region was a site of several intense in several days. From the results, it showed that the burst is formed from the explosion of M-class solar flare which can be observed at 412UT. As a conclusion, a good agreement was reached and we believe that Sun’s activities are more active to pursuit the solar maximum cycle.

Magnetotail current contribution to the Dst Index Using the MT Index and the WINDMI model

In this paper, we have improved the capabilities of a low dimensional nonlinear dynamical model called WINDMI to determine the state of the global magnetosphere by employing the magnetotail (MT) index as a measurement constraint during large geomagnetic storms. The MT index is derived from particle precipitation measurements made by the NOAA/POES satellites. This index indicates the location of the nightside ion isotropic boundary, which is then used as a proxy for the strength of the magnetotail current in the magnetosphere. In Asikainen et al. (2010), the contribution of the tail current to the Dst index is estimated from an empirical relationship based on the MT index. Here the WINDMI model is used as a substitute to arrive at the tail current and ring current contribution to the Dst index, for comparison purposes. We run the WINDMI model on 7 large geomagnetic storms, while optimizing the model state variables against the Dst index, the MT index, and the AL index simultaneously. Our results show that the contribution from the geotail current produced by the WINDMI model and the MT index are strongly correlated, except during some periods when storm time substorms are observed. The inclusion of the MT index as an optimization constraint in turn increases our confidence that the ring current contribution to the Dst index calculated by the WINDMI model is correct during large geomagnetic storms.

The Beginning Impulsive of Solar Burst Type IV Radio Emission Detection Associated with M Type Solar Flare

First light detection of solar burst type IV in Malaysia in the region of 260 MHz till 380 MHz has been successfully detected on 5 th March 2012. This significant solar burst variations is associated with solar flare type M level 2.0 occurred from 0412UT. Due to the effect, strong bursts that caused by extraordinary solar flares due to magnetic reconnection effect potentially induced in the near-Earth magneto tail. One possible reason behind the formation of this very complex long duration of this loop is the magnetic reconnection and disruption of the loops which is observed during flare maximum. Sunspot 1429 active region was a site of several intense in several days. In Malaysia, monitoring solar burst in radio region is just in beginning by involved the project under International Space Weather Initiative (ISWI) since 2011. We also analyzed multi wavelength observation from different sites as continuity of the phenomenon. Observations presented in this paper confirmed that Malaysia can be one of the potential countries to focus on solar monitoring solar radio emission at lowbroadband frequency (45-870) MHz using ground-based telescope due to 12 hours per day throughout a year.

Timing and location of substorm onsets from THEMIS satellite and ground based observations

Abstract. The unprecedented coverage of the THEMIS GBO station network coupled with high temporal and spatial resolution allowed us to determine the various stages of the global scale developments of the optical aurora at substorm onsets. We identified several steps of the substorm onset auroral phenomena and we suggest that the most rapid development is the starting of the Substorm Poleward Expansion (SPE) and it is most useful for accurate timing of the substorm onset. The physical significance of this step is the start of the large scale substorm energy dissipation in the atmosphere due to particle precipitation and auroral electrojet currents. We also recognized several pre-cursor features. We also measured the time of arrival of magnetic impulses associated with the same substorms at the THEMIS satellites. We used these times and a simple model with assumed iono-acoustic speeds in the range of 300–800 km/s to calculate the location and time of the origin of the magnetic impulses propagating from substorm onset. The assumption was made that the substorm occurred between two THEMIS satellites and the impulses propagated away from a singular starting point in and out along the magneto tail GSM-x axis. This technique is only useful in cases where the ground based signature of the substorm is very close in local time (or longitude) to the foot of the field lines of the THEMIS satellites. The x distance of the calculated origins were naturally highly dependent on the assumed propagation velocity model and the associated magneto-sonic speed. The resulting x distances of the starting point for the three events ranged between 11 and 17.6 RE. denoting a starting region that requires highly stretched field lines to map to the auroral onset latitude but which is generally considered to be too close for neutral line formation. The corresponding start times were in the range of 0 to 170 s prior SPE depending strongly on the assumed propagation speed.

Magnetospheric Configuration with Magnetotail Current

Magnetospheric configuration with magneto tail current is studied on a two-dimensional formulation. The planar magnetic field is represented by an analytic function of a complex variable that represents points of the. Noon-midnight plane. In our treatment, which accounts for both-the Chapman-Ferraro magnetopause current and the magnetotail current, the function that describes the ffl3gnetospheric magnetic field is a rational function. Thus, the magnetic neutral points, which characterize the magnetic topology of the field lines, can be simply ascertained by finding the roots of a polynomial function. The function for the magnetic field is the derivative off a complex potential, the real part of which is a flux function and the imaginary part a magnetic potential of the magnetic field. The inverse function of the complex potential describes the position variable in terms of the complex potential. Field lines are described by a parametric equation obtainable from the afore-mentioned inverse function. Thus, no integration off the differential equation for field lines is needed.

On ultralow frequency waves in the lobes of the Earth's magnetotail

Motivated by Thermal Catastrophe Model (TCM) of Goertz and Smith (1989), we turn attention to ultralow frequency (ULF) waves in the lobes, where waves are usually of relatively low amplitude. Remarkably little attention has been paid to characterizing the lobe spectra and the relation of lobe wave power to geophysical processes. In this paper we examine ULF waves (0.26 to 5 mHz or 3.2‐ to 64‐min periods) in the Earth's magneto tail lobe region (−10 ≲ XGSM ≲ −23 RE) using data from the ISEE 2 flux gate magnetometer. The studies used all the tail data from the year 1978. Data from the ISEE 2 Fast Plasma Experiment (FPE) enabled us to exclude from the analysis all intervals not in the tail lobe region. The relation between the substorm activity, characterized by the AE index, and the wave power is also described. We find that the wave amplitudes at periods of ∼3 to 16 min (∼1 to 5 mHz) are below 0.8 nT for the transverse magnetic field components and below 0.6 nT for the compressional components ∼90% of the time. The amplitudes of lower frequency waves are somewhat larger. For waves with periods 16 to 64 min (∼0.26 to 1 mHz) the amplitudes are below 1 nT for both the compressional and transverse components ∼90% of the time. The wave amplitudes and the AE index, which characterizes substorm activity, are weakly correlated, the correlation coefficients being ∼0.55 and ∼0.35, for the compressional and transverse components respectively. The correlation coefficients between the transverse wave amplitudes and the AE index change little when AE is taken for 1 hour prior to or subsequent to the hour in which the wave amplitude is measured. For the compressional component the correlation coefficient remains unchanged when AE is measured for the subsequent or simultaneous hour but decreases when AE is taken for the previous hour. A primarily statistical study of frequency‐weighted power of ULF waves at frequencies of 1 to 5 mHz is provided. The probability is 50% (5%) of observing frequency‐weighted power for the frequency range 1 to 5 mHz in excess of 10−4 nT² Hz (10−3 nT² Hz). Three extended intervals in the lobe were selected for case studies. The largest wave amplitude we observed was about 5 nT which occurred when the AE index was higher than 1500 nT. The period corresponding to the largest wave amplitudes was ∼35 min (∼0.48 mHz). Power spectra from three different substorm intervals are provided as examples of wave activity in the lobes. The power spectral density of all components falls off as ƒ−2 or faster. Statistical study by itself does not provide an appropriate test of the requirement on wave power for the TCM. Additional case studies using ground magnetometers to relate wave power to substorm phases will be needed to test the assumptions of the TCM.

Magnetotail Physics

When a rapidly moving low‐density plasma encounters a massive magnetized object in space, a tail of magnetic field lines typically forms behind the object. Some of the field lines that thread through the central body are stretched out in the downstream direction be cause of frictional processes that act between the body's own field lines and the passing plasma. Such “magnetotails” have been observed repeatedly in our Solar System. Each of the explored planets has a magnetotail, including even Venus. This planet has negligible intrinsic magnetism but its ionosphere traps and holds interplanetary field lines, which are then dragged back into a magneto tail. Comets exhibit their own versions of the magnetotail phenomenon, and there is evidence that analogous structures on a vastly larger scale form downstream of certain radio galaxies that move through the intergalactic medium in clusters of galaxies.

Jovian electron populations in the magnetosphere of Mercury

A mechanism to explain the existence of two distinctly different kinds of energetic electron bursts within the Hermean magnetosphere is presented. The spectrally‐soft, very intense increases of energetic electrons observed in situ by Mariner 10 are ascribed to "substorm‐like" dissipation events due to magnetic reconnection in Mercury's magneto tail. The other type of electron bursts observed in Mercury's magnetosphere, characterized by lower peak intensities and much harder energy spectra, are attributed to Jovian electrons which first enter and are subsequently confined in the Hermean system. This Jovian electron model at Mercury is closely analogous to a similar model of such Jovian electron effects within the terrestrial magnetosphere. Such a model eliminates the need for the Hermean magnetosphere to produce highly relativistic electron bursts by internal generation mechanisms.

Electron energization in the geomagnetic tail current sheet

Electron motion in the distant tail current sheet is evaluated and found to violate the guiding center approximation at energies ≳ 100 eV. Most electrons within the energy range ˜10−1 ‐ 10² keV that enter the current sheet become trapped within the magnetic field reversal region. These electrons then convect earthward and gain energy from the cross‐tail electric field. If the energy spectrum of electrons entering the current sheet is similar to that of electrons from the boundary layer surrounding the magneto tail, the energy gain from the electric field produces electron energy spectra comparable to those observed in the earth's plasma sheet. Thus current sheet interactions can be a significant source of particles and energy for plasma sheet electrons as well as for plasma sheet ions. A small fraction of electrons within the current sheet has its pitch angles scattered so as to be ejected from the current sheet within the atmospheric loss cone. These electrons can account for the electron precipitation near the high‐latitude boundary of energetic electrons, which is approximately isotropic in pitch angle up to at least several hundred keV. Current sheet interaction should cause approximately isotropic auroral precipitation up to several hundred keV energies, which extends to significantly lower latitudes for ions than for electrons in agreement with low‐altitude satellite observations. Electron precipitation associated with diffuse aurora generally has a transition at 1–10 keV to anisotropic pitch angle distributions. Such electron precipitation cannot be explained by current sheet interactions, but it can be explained by pitch angle diffusion driven by plasma turbulence.

Association of plasma sheet thinning with neutral line formation in the magnetotail

Magnetotail electron observations by Vela satellites (at a radial distance of about 18 RE) and tail magnetic field observations by Explorer 34 (when its distance is beyond 25 RE) are combined. They support the belief, advanced earlier, that during substorms a neutral line is formed in the near-tail region, earthward of the Vela orbit, and its formation leads to the rapid (further) thinning of the plasma sheet beyond its distance. The intervals with the neutral line and the associated thin plasma sheet have a duration of 0.5 to 1 hour, and they appear intermittently after intervals of energy storage in the magneto tail. In the ground magnetograms from the auroral zone the formation and the disappearance of the neutral line are reflected most sensitively around the premidnight region and correspond, respectively, to the intensification and the peak (and beginning of recovery) of the negative bay activity.

Geomagnetic storm particles in the high-latitude magnetotail

Nearly monoenergetic positive ions flowing outward along magnetic-field lines in the high-latitude magneto tail at ∼18 RE, outside the plasma sheet, have been observed with Vela satellites. These ions, probably mainly protons, are detected only during geomagnetic storms. The ‘storm particles’ have average energies per charge ranging from about 0.3 to 3 kv, but at any instant the energy distribution is quite narrow, sometimes <10%. Their angular distribution is usually narrow, sometimes ∼6°. Particles with storm-particle characteristics are not observed in the plasma sheet. Storm-particle fluxes cannot be determined with high accuracy because of their narrow energy distribution, but they are estimated to reach 105 particles cm−2 sec−1 or more. Possible sources of the storm particles are considered, including the solar wind, magnetosheath, polar cusps, polar wind or ionosphere, plasma sheet, solar neutral hydrogen streams, reconnection transfer of plasma into the magneto tail from the polar cusps, polar wind, or polar ionosphere, and parallel electric-field acceleration of the polar wind or ionosphere ions along polar-cap magnetic-field lines. Of these possibilities, the electric-field acceleration is favored. No matter what their source, storm particles appear to be a new feature of geomagnetic storms.