Global Survey and Empirical Model of Fast Magnetosonic Waves Over Their Full Frequency Range in Earth's Inner Magnetosphere

2019 ◽  
Vol 124 (12) ◽  
pp. 10270-10282 ◽  
Author(s):  
Q. Ma ◽  
W. Li ◽  
J. Bortnik ◽  
C. A. Kletzing ◽  
W. S. Kurth ◽  
...  
Keyword(s):  
Empirical Model ◽  
Frequency Range ◽  
Inner Magnetosphere ◽  
Global Survey

scholarly journals Empirical model of proton fluxes in the equatorial inner magnetosphere: Development

2001 ◽  
Vol 106 (A11) ◽  
pp. 25713-25729 ◽  
Author(s):  
A. Milillo ◽  
S. Orsini ◽  
I. A. Daglis
Keyword(s):  
Empirical Model ◽  
Inner Magnetosphere ◽  
Proton Fluxes

scholarly journals Observations of lower hybrid cavities in the inner magnetosphere by the Cluster and Viking satellites

2004 ◽  
Vol 22 (8) ◽  
pp. 2961-2972 ◽  
Author(s):  
A. Tjulin ◽  
M. André ◽  
A. I. Eriksson ◽  
M. Maksimovic
Keyword(s):  
Time Scales ◽  
Sounding Rocket ◽  
Lower Hybrid ◽  
High Altitudes ◽  
Frequency Range ◽  
General Shape ◽  
Lower Altitude ◽  
Inner Magnetosphere ◽  
Hybrid Frequency ◽  
The Individual

Abstract. Observations by the Viking and Cluster satellites at altitudes up to 35000km show that Lower Hybrid Cavities (LHCs) are common in the inner magnetosphere. LHCs are density depletions filled with waves in the lower hybrid frequency range. The LHCs have, until recently, only been found at altitudes up to 2000km. Statistics of the locations and general shape of the LHCs is performed to obtain an overview of some of their properties. In total, we have observed 166 LHCs on Viking during 27h of data, and 535 LHCs on Cluster during 87h of data. These LHCs are found at invariant latitudes from the auroral region to the plasmapause. A comparison with lower altitude observations shows that the LHC occurrence frequency does not scale with the flux tube radius, so that the LHCs are moderately rarer at high altitudes. This indicates that the individual LHCs do not reach from the ionosphere to 35000km altitude, which gives an upper bound for their length. The width of the LHCs perpendicular to the geomagnetic field at high altitudes is a few times the ion gyroradius, consistent with observations at low altitudes. The estimated depth of the density depletions vary with altitude, being larger at altitudes of 20000-35000km (Cluster, 10-20%), smaller around 1500-13000km (Viking and previous Freja results, a few percent) and again larger around 1000km (previous sounding rocket observations, 10-20%). The LHCs in the inner magnetosphere are situated in regions with background electrostatic hiss in the lower hybrid frequency range, consistent with investigations at low altitudes. Individual LHCs observed at high altitudes are stable at least on time scales of 0.2s (about the ion gyro period), which is consistent with previous results at lower altitudes, and observations by the four Cluster satellites show that the occurrence of LHCs in a region in space is a stable phenomenon, at least on time scales of an hour.

Empirical model of proton fluxes in the equatorial inner magnetosphere: 2. Properties and applications

2003 ◽  
Vol 108 (A5) ◽  
Author(s):  
A. Milillo ◽  
S. Orsini ◽  
D. C. Delcourt ◽  
A. Mura ◽  
S. Massetti ◽  
...  
Keyword(s):  
Empirical Model ◽  
Inner Magnetosphere ◽  
Proton Fluxes

Empirical model of the inner magnetosphere H+ pitch angle distributions

2005 ◽  
pp. 283-291 ◽  
Author(s):  
Jacopo De Benedetti ◽  
Anna Milillo ◽  
Stefano Orsini ◽  
Alessandro Mura ◽  
Elisabetta De Angelis ◽  
...  
Keyword(s):  
Empirical Model ◽  
Pitch Angle ◽  
Inner Magnetosphere

scholarly journals Variations in cosmic ray cutoff rigidities during the greatgeomagnetic storm of November 2004

10.12737/7890 ◽  
2015 ◽  
Vol 1 (2) ◽  
pp. 97-105 ◽  
Author(s):  
Марта Тясто ◽  
Marta Tyasto ◽  
Ольга Данилова ◽  
Olga Danilova ◽  
Наталия Птицына ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Correlation Coefficients ◽  
Cosmic Ray ◽  
Survey Method ◽  
Cutoff Rigidity ◽  
Low Latitude ◽  
Inner Magnetosphere ◽  
Global Survey ◽  
Dst Index ◽  
Tracing Method

Very strong interplanetary and magnetospheric disturbance observed on 7–13 November 2004 can be regarded as one of the strongest events during the entire period of space observations. In this paper, we report on the studies of cosmic ray cutoff rigidity variations during 7–13 November 2004 showing how storm conditions can affect the direct cosmic ray access to the inner magnetosphere. Effective cutoff rigidities have been calculated for selected points on the ground by tracing trajectories of cosmic ray particles through the magnetospheric magnetic field of the “storm-oriented” Tsyganenko 2003 model [Tsyganenko, 2002a, b; Tsyganenko et al., 2003]. Cutoff rigidity variations have also been determined by the spectrographic global survey method on the basis of experimental data of the neutron monitor network. Correlations between the calculated and experimental cutoff rigidities, as well as between geomagnetic Dst index and interplanetary parameters have been investigated. Correlation coefficients between the cutoff rigidities obtained by the trajectory tracing method and the spectrographic global survey method have been found to be in the limits of 0.76–0.89 for all stations except the low-latitude station Tokyo (0.35). The most pronounced correlation has been revealed between the cutoff rigidities that exhibited a very large variation of 1–1.5 GV during the magnetic storm, and the Dst index.

Energy-dependent Boundaries of Earth's Radiation Belt Electron Slot Region

2021 ◽  
Vol 922 (2) ◽  
pp. 246
Author(s):  
Yang Mei ◽  
Yasong Ge ◽  
Aimin Du ◽  
Xudong Gu ◽  
Danny Summers ◽  
...  
Keyword(s):  
Empirical Model ◽  
Radiation Belt ◽  
Lower Boundary ◽  
Recovery Process ◽  
Compression Process ◽  
Inner Magnetosphere ◽  
P Index ◽  
Energy Dependent ◽  
Geomagnetic Activities ◽  
Dependent Processes

Abstract The variations in radiation belt boundaries reflect competition between acceleration and loss physical processes of energetic electrons, which is an important issue for radiation belts of planets with an internal magnetic field (e.g., Earth, Jupiter, and Saturn). Based on high-quality measurements from Van Allen Probes spanning the years 2014–2018, we develop an empirical model of the energy-dependent boundaries of Earth's electron radiation belt slot region, showing that the lower boundary follows a logarithmic function of the electron energy while the upper boundary is controlled by two competing energy-dependent processes, namely compression and recovery. The compression process relates linearly to a 15 hr averaged Kp index, while the recovery process is found to be approximately proportional to time. Detailed data-model comparisons demonstrate that our model, using only the Kp index and time epoch as inputs, reconstructs the slot region boundaries in real time for 200 keV to 2 MeV electrons under varying geomagnetic conditions. Such a data-driven empirical model is prerequisite to understanding the dynamic changes of the slot region in response to both solar and geomagnetic activities. The model can be readily incorporated into future global simulations of radiation belt electron dynamics in Earth's inner magnetosphere and provide new insights into the study of Saturn's and Jupiter's radiation belt variability.

An empirical model of ion plasma in the inner magnetosphere derived from CRRES/MICS measurements

2016 ◽  
Vol 121 (12) ◽  
pp. 11,780-11,797 ◽  
Author(s):  
S. G. Claudepierre ◽  
M. W. Chen ◽  
J. L. Roeder ◽  
J. F. Fennell
Keyword(s):  
Empirical Model ◽  
Inner Magnetosphere ◽  
Ion Plasma

Density-based discrimination of protein and RNA in the ribosome

1992 ◽  
Vol 50 (1) ◽  
pp. 464-465
Author(s):  
Joachim Frank
Keyword(s):  
Transfer Function ◽  
Spatial Frequency ◽  
Three Dimensional ◽  
Wiener Filter ◽  
Dark Field Image ◽  
Dark Field ◽  
Frequency Range ◽  
Bright Field ◽  
Contrast Transfer Function ◽  
Pass Filter

Cryo-electron microscopy combined with single-particle reconstruction techniques has allowed us to form a three-dimensional image of the Escherichia coli ribosome.In the interior, we observe strong density variations which may be attributed to the difference in scattering density between ribosomal RNA (rRNA) and protein. This identification can only be tentative, and lacks quantitation at this stage, because of the nature of image formation by bright field phase contrast. Apart from limiting the resolution, the contrast transfer function acts as a high-pass filter which produces edge enhancement effects that can explain at least part of the observed variations. As a step toward a more quantitative analysis, it is necessary to correct the transfer function in the low-spatial-frequency range. Unfortunately, it is in that range where Fourier components unrelated to elastic bright-field imaging are found, and a Wiener-filter type restoration would lead to incorrect results. Depending upon the thickness of the ice layer, a varying contribution to the Fourier components in the low-spatial-frequency range originates from an “inelastic dark field” image. The only prospect to obtain quantitatively interpretable images (i.e., which would allow discrimination between rRNA and protein by application of a density threshold set to the average RNA scattering density may therefore lie in the use of energy-filtering microscopes.

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