Low Frequency ULF Waves in the Earth’s Inner Magnetosphere: Statistics During Coronal Mass Ejections and Seeding of EMIC Waves

2021 ◽  
Author(s):  
Konstantin V. Gamayunov ◽  
Mark J. Engebretson
Keyword(s):  
Coronal Mass Ejections ◽  
Low Frequency ◽  
Ulf Waves ◽  
Inner Magnetosphere ◽  
Emic Waves

scholarly journals Modulation of chorus intensity by ULF waves deep in the inner magnetosphere

2016 ◽  
Vol 43 (18) ◽  
pp. 9444-9452 ◽  
Author(s):  
Zhiyang Xia ◽  
Lunjin Chen ◽  
Lei Dai ◽  
Seth G. Claudepierre ◽  
Anthony A. Chan ◽  
...  
Keyword(s):  
Ulf Waves ◽  
Inner Magnetosphere

Direct measurements of cold and hot plasma composition and EMIC waves in the outer magnetosphere: Implications for inner magnetosphere wave-particle interactions

2021 ◽  
Author(s):  
Justin Lee ◽  
Drew Turner ◽  
Sarah Vines ◽  
Robert Allen ◽  
Sergio Toledo-Redondo
Keyword(s):  
Unstable Wave ◽  
Linear Wave ◽  
Plasma Composition ◽  
Inner Magnetosphere ◽  
Hot Plasma ◽  
Emic Wave ◽  
Direct Measurements ◽  
Wave Numbers ◽  
Emic Waves

<p>Although thorough characterization of magnetospheric ion composition is rare for EMIC wave studies, convective processes that occur more frequently in Earth’s outer magnetosphere have allowed the Magnetospheric Multiscale (MMS) satellites to make direct measurements of the cold and hot plasma composition during EMIC wave activity. We will present an observation and linear wave modeling case study conducted on EMIC waves observed during a perturbed activity period in the outer dusk-side magnetosphere. During the two intervals investigated for the case study, the MMS satellites made direct measurements of cold plasmaspheric plasma in addition to multiple hot ion components at the same time as EMIC wave emissions were observed. Applying the in-situ plasma composition data to wave modeling, we find that wave growth rate is impacted by the complex interactions between the cold as well as the hot ion components and ambient plasma conditions. In addition, we observe that linear wave properties (unstable wave numbers and band structure) can significantly evolve with changes in cold and hot ion composition. Although the modeling showed the presence of dense cold ions can broaden the range of unstable wave numbers, consistent with previous work, the hot heavy ions that were more abundant nearer storm main phase could limit the growth of EMIC waves to smaller wave numbers. In the inner magnetosphere, where higher cold ion density is expected, the ring current heavy ions could also be more intense near storm-time, possibly resulting in conditions that limit the interactions of EMIC waves with trapped radiation belt electrons to multi-MeV energies. Additional investigation when direct measurements of cold and hot plasma composition are available could improve understanding of EMIC waves and their interactions with trapped energetic particles in the inner magnetosphere.</p>

Foreshock ULF fluctuations near the Moon: THEMIS observations

2021 ◽  
Author(s):  
Anna Salohub ◽  
Jana Šafránková ◽  
Zdeněk Němeček
Keyword(s):  
Solar Wind ◽  
Rest Frame ◽  
Low Frequency ◽  
Solar Wind Plasma ◽  
Turbulent Plasma ◽  
Bow Shock ◽  
Ulf Waves ◽  
The Moon ◽  
Shock Surface ◽  
The Earth

<p>The foreshock is a region filled with a turbulent plasma located upstream the Earth’s bow shock where interplanetary magnetic field (IMF) lines are connected to the bow shock surface. In this region, ultra-low frequency (ULF) waves are generated due to the interaction of the solar wind plasma with particles reflected from the bow shock back into the solar wind. It is assumed that excited waves grow and they are convected through the solar wind/foreshock, thus the inner spacecraft (close to the bow shock) would observe larger wave amplitudes than the outer (far from the bow shock) spacecraft. The paper presents a statistical analysis of excited ULF fluctuations observed simultaneously by two closely separated THEMIS spacecraft orbiting the Moon under a nearly radial IMF. We found that ULF fluctuations (in the plasma rest frame) can be characterized as a mixture of transverse and compressional modes with different properties at both locations. We discuss the growth and/or damping of ULF waves during their propagation.</p>

scholarly journals Low Frequency Radio Astronomy from Above the Ionosphere

2002 ◽  
Vol 199 ◽  
pp. 488-489
Author(s):  
D. L. Jones
Keyword(s):  
High Resolution ◽  
Radio Astronomy ◽  
Coronal Mass Ejections ◽  
Solar Radio ◽  
Low Frequency ◽  
Dramatic Improvement ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Low Frequencies ◽  
High Resolution Images

The GMRT represents a dramatic improvement in ground-based observing capabilities for low frequency radio astronomy. At sufficiently low frequencies, however, no ground-based facility will be able to produce high resolution images while looking through the ionosphere. A space-based array will be needed to explore the objects and processes which dominate the sky at the lowest radio frequencies. An imaging radio interferometer based on a large number of small, inexpensive satellites would be able to track solar radio bursts associated with coronal mass ejections out to the distance of Earth, determine the frequency and duration of early epochs of nonthermal activity in galaxies, and provide unique information about the interstellar medium.

scholarly journals How Do Ultra‐Low Frequency Waves Access the Inner Magnetosphere During Geomagnetic Storms?

2019 ◽  
Vol 46 (19) ◽  
pp. 10699-10709 ◽  
Author(s):  
I. Jonathan Rae ◽  
Kyle R. Murphy ◽  
Clare E.J. Watt ◽  
Jasmine K. Sandhu ◽  
Marina Georgiou ◽  
...  
Keyword(s):  
Geomagnetic Storms ◽  
Low Frequency ◽  
Inner Magnetosphere ◽  
Low Frequency Waves

scholarly journals Geomagnetic activity and local time dependence of the distribution of ultra low-frequency wave power in azimuthal wavenumbers, <i>m</i>

2017 ◽  
Vol 35 (3) ◽  
pp. 629-638 ◽  
Author(s):  
Theodore E. Sarris ◽  
Xinlin Li
Keyword(s):  
Phase Difference ◽  
Low Frequency ◽  
Field Measurements ◽  
Resonant Interaction ◽  
Total Power ◽  
Ulf Waves ◽  
Quiet Time ◽  
Frequency Wave ◽  
Drift Frequency ◽  
Diffusion Rates

Abstract. The azimuthal wavenumber m of ultra low-frequency (ULF) waves in the magnetosphere is a required parameter in the calculations of the diffusion rates of energetic electrons and protons in the magnetosphere, as electrons and protons of drift frequency ωd have been shown to radially diffuse due to resonant interaction with ULF waves of frequency ω = mωd. However, there are difficulties in estimating m, due to lack of multipoint measurements. In this paper we use magnetic field measurements at geosynchronous orbit to calculate the cross-spectrogram power and phase differences between time series from magnetometer pairs. Subsequently, assuming that ULF waves of a certain frequency and m would be observed with a certain phase difference between two azimuthally aligned magnetometers, the fraction of the total power in each phase difference range is calculated. As part of the analysis, both quiet-time and storm-time distributions of power per m number are calculated, and it is shown that during active times, a smaller fraction of total power is confined to lower m than during quiet times. It is also shown that in the dayside region, power is distributed mostly to the lowest azimuthal wavenumbers m = 1 and 2, whereas on the nightside it is more equally distributed to all m that can be resolved by the azimuthal separation between two spacecraft.

Nonlinear Landau resonance between EMIC waves and cold electrons in the inner magnetosphere

2019 ◽  
Vol 26 (4) ◽  
pp. 042903 ◽  
Author(s):  
Bin Wang ◽  
Pengyuan Li ◽  
Jian Huang ◽  
Bing Zhang
Keyword(s):  
Inner Magnetosphere ◽  
Cold Electrons ◽  
Emic Waves

ULF waves and their influence on radiation belt dynamics in Earth's magnetosphere

2020 ◽  
Author(s):  
Robert Rankin ◽  
Alexander Degeling
Keyword(s):  
Radiation Belt ◽  
Geomagnetic Storms ◽  
Low Frequency ◽  
Recovery Phase ◽  
Ulf Waves ◽  
Wave Source ◽  
Initial Plasma ◽  
Plasma State ◽  
Van Allen Probes ◽  
Geomagnetic Fields

&lt;p&gt;Recent observations from the Van Allen Probes mission have established that Pc3-5 ultra-low-frequency (ULF) waves can energize ions and electrons via drift-resonance and drift-bounce resonance. The extent to which these waves contribute to the space weather of the belts is relatively poorly understood and requires sophisticated modelling and characterization of the dominant wave modes that arise in the development and recovery phase of geomagnetic storms. Despite more than four decades of observations and theoretical analysis of ULF waves, there is no framework for accurately assessing the global distribution of ULF waves and their influence on the ring current.&amp;#160;&lt;br&gt;In this presentation, we describe a new global model of ULF waves that incorporates non-dipolar geomagnetic fields. The model is constrained using the GCPM of cold plasma density model and a specification of the ionosphere using the IRI and MSIS models. An algorithm is applied to adjust the initial plasma state to a quasi-static equilibrium that is then driven by a global convection electric field and ULF wave source. For specific observations by the Van Allen Probes and ARASE mission, the effect of these ULF waves on radiation belt ions and electrons is evaluated utilizing test-particle methodology and Liouville's theorem, which enables the phase space density to be followed and compared one-for-one with the satellite observations. &amp;#160;&lt;/p&gt;

New remote radio observations of Jupiter by Parker Solar Probe

2020 ◽  
Author(s):  
Alain Lecacheux ◽  
Stuart D. Bale ◽  
Milan Maksimovic ◽  
Marc Pulupa
Keyword(s):  
Low Frequency ◽  
Dynamic Spectrum ◽  
Plasma Structure ◽  
The Sun ◽  
Radio Observations ◽  
Inner Magnetosphere ◽  
Radio Emissions

&lt;p&gt;The FIELDS/RFS experiment aboard the Parker Solar Probe spacecraft, in orbit around the Sun, is able to detect and remotely study low frequency radio emissions from Jupiter. Accurate measurements of the intensity and polarisation of those emissions (mainly the HOM/DAM components) were obtained throughout years 2018 and 2019. They are compared to similar ones, obtained 20 years ago, during Cassini&amp;#8217;s remote flyby of Jupiter. A particular emphasis is brought on the so-called &amp;#8220;attenuation bands&amp;#8221; phenomenon, - a well-defined intensity extinction/enhancement feature modulating the HOM dynamic spectrum -, which likely results from the radiation propagating to the observer through some permanent or long lived plasma structure (not firmly identified so far) lying in the rotating Jovian inner magnetosphere.&lt;/p&gt;

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