Storm time occurrence and spatial distribution of Pc4 poloidal ULF waves in the inner magnetosphere: A Van Allen Probes statistical study

Abstract. Spatial distribution and source region size of chorus waves are important parameters in understanding their generation.In this work, we analyze over 3 years of continuous wave burst mode data from Van Allen Probes and build a data set of rising and falling tone chorus. For the L shell range covered by Van Allen Probes data (3.5 ≤ L ≤ 7), statistical results demonstrate that the sector where rising tones are most likely to be observed is the dayside during geomagnetically quiet and moderate times and the dawnside during active times. Moreover, rising tone chorus waves have a higher occurrence rate near the equatorial plane, while the falling tone chorus waves have a higher possibility to be observed at lower L-shell and higher magnetic latitude. By analyzing the direction of Poynting wave vector, we statistically investigate the chorus source region size along a field line, and compare the results with previous theoretical estimates. Our analysis confirms previous conclusions that both rising tone and falling tone chorus waves are generated near the equatorial plane, and shows that previous theoretical estimates roughly agree with the observation within a factor of two. Our results provide important insights into further understanding of chorus generation.

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A statistical study of the spatial distribution and source-region size of chorus waves using Van Allen Probes data

Annales Geophysicae ◽

10.5194/angeo-36-867-2018 ◽

2018 ◽

Vol 36 (3) ◽

pp. 867-878 ◽

Cited By ~ 4

Author(s):

Shangchun Teng ◽

Xin Tao ◽

Wen Li ◽

Yi Qi ◽

Xinliang Gao ◽

...

Keyword(s):

Spatial Distribution ◽

Equatorial Plane ◽

Statistical Study ◽

Continuous Wave ◽

Source Region ◽

Occurrence Rate ◽

Data Set ◽

Chorus Waves ◽

Van Allen Probes ◽

Region Size

Abstract. The spatial distribution and source-region size of chorus waves are important parameters for understanding their generation. In this work, we analyze over 3 years of continuous wave burst-mode data from the Van Allen Probes mission and build a data set of rising-tone and falling-tone chorus waves. For the L shell range covered by Van Allen Probes data (3.5≤L≤7), statistical results demonstrate that the sector where rising tones are most likely to be observed is the dayside during geomagnetically quiet and moderate times and the dawn side during active times. Moreover, rising-tone chorus waves have a higher occurrence rate near the equatorial plane, while the falling-tone chorus waves have a higher possibility to be observed at lower L shell and higher magnetic latitudes. By analyzing the direction of the Poynting wave vector, we statistically investigate the chorus source-region size along a field line, and compare the results with previous theoretical estimates. Our analysis confirms previous conclusions that both rising-tone and falling-tone chorus waves are generated near the equatorial plane, and shows that previous theoretical estimates roughly agree with the observation within a factor of 2. Our results provide important insights into further understanding of chorus generation.

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Statistical study of the storm time radiation belt evolution during Van Allen Probes era: CME- versus CIR-driven storms

Journal of Geophysical Research Space Physics ◽

10.1002/2017ja024100 ◽

2017 ◽

Vol 122 (8) ◽

pp. 8327-8339 ◽

Cited By ~ 21

Author(s):

Xiao-Chen Shen ◽

Mary K. Hudson ◽

Allison N. Jaynes ◽

Quanqi Shi ◽

Anmin Tian ◽

...

Keyword(s):

Radiation Belt ◽

Statistical Study ◽

Van Allen Probes

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

Geophysical Research Letters ◽

10.1002/2016gl070280 ◽

2016 ◽

Vol 43 (18) ◽

pp. 9444-9452 ◽

Cited By ~ 15

Author(s):

Zhiyang Xia ◽

Lunjin Chen ◽

Lei Dai ◽

Seth G. Claudepierre ◽

Anthony A. Chan ◽

...

Keyword(s):

Ulf Waves ◽

Inner Magnetosphere

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Foreshock cavitons and spontaneous hot flow anomalies: A statistical study with a global hybrid-Vlasov simulation

10.5194/angeo-2020-87 ◽

2021 ◽

Author(s):

Vertti Tarvus ◽

Lucile Turc ◽

Markus Battarbee ◽

Jonas Suni ◽

Xóchitl Blanco-Cano ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Rest Frame ◽

Statistical Study ◽

Plasma Temperature ◽

Propagation Speed ◽

Bow Shock ◽

Ulf Waves ◽

Subsequent Formation ◽

Comparable Amount

Abstract. The foreshock located upstream of Earth's bow shock hosts a wide variety of phenomena related to the reflection of solar wind particles from the bow shock and the subsequent formation of ultra-low frequency (ULF) waves. In this work, we investigate foreshock cavitons, which are transient structures resulting from the non-linear evolution of ULF waves, and spontaneous hot flow anomalies (SHFAs), which evolve from cavitons as they accumulate suprathermal ions while being carried to the bow shock by the solar wind. Using the global hybrid-Vlasov simulation model Vlasiator, we have conducted a statistical study in which we track the motion of individual cavitons and SHFAs in order to examine their properties and evolution. In our simulation run where the interplanetary magnetic field (IMF) is directed at a sunward-southward angle of 45 degrees, continuous formation of cavitons is found up to ~ 11 Earth radii (RE) from the bow shock (along the IMF direction), and caviton-to-SHFA evolution takes place within ~ 2 RE from the shock. A third of the cavitons in our run evolve into SHFAs, and we find a comparable amount of SHFAs forming independently near the bow shock. We compare the properties of cavitons and SHFAs to prior spacecraft observations and simulations, finding good agreement. We also investigate the variation of the properties as a function of position in the foreshock, showing that the transients close to the bow shock are associated with larger depletions in the plasma density and magnetic field magnitude, along with larger increases in the plasma temperature and the level of bulk flow deflection. Our measurements of the propagation velocities of cavitons and SHFAs agree with earlier studies, showing that the transients propagate sunward in the solar wind rest frame. We show that SHFAs have a greater solar wind rest frame propagation speed than cavitons, which is related to an increase in the magnetosonic speed near the bow shock.

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Foreshock cavitons and spontaneous hot flow anomalies: a statistical study with a global hybrid-Vlasov simulation

Annales Geophysicae ◽

10.5194/angeo-39-911-2021 ◽

2021 ◽

Vol 39 (5) ◽

pp. 911-928

Author(s):

Vertti Tarvus ◽

Lucile Turc ◽

Markus Battarbee ◽

Jonas Suni ◽

Xóchitl Blanco-Cano ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Rest Frame ◽

Statistical Study ◽

Plasma Temperature ◽

Propagation Speed ◽

Bow Shock ◽

Ulf Waves ◽

Subsequent Formation ◽

Comparable Amount

Abstract. The foreshock located upstream of Earth's bow shock hosts a wide variety of phenomena related to the reflection of solar wind particles from the bow shock and the subsequent formation of ultra-low-frequency (ULF) waves. In this work, we investigate foreshock cavitons, which are transient structures resulting from the non-linear evolution of ULF waves, and spontaneous hot flow anomalies (SHFAs), which are thought to evolve from cavitons as they accumulate suprathermal ions while being carried to the bow shock by the solar wind. Using the global hybrid-Vlasov simulation model Vlasiator, we have conducted a statistical study in which we track the motion of individual cavitons and SHFAs in order to examine their properties and evolution. In our simulation run where the interplanetary magnetic field (IMF) is directed at a sunward–southward angle of 45∘, continuous formation of cavitons is found up to ∼11 Earth radii (RE) from the bow shock (along the IMF direction), and caviton-to-SHFA evolution takes place within ∼2 RE from the shock. A third of the cavitons in our run evolve into SHFAs, and we find a comparable amount of SHFAs forming independently near the bow shock. We compare the properties of cavitons and SHFAs to prior spacecraft observations and simulations, finding good agreement. We also investigate the variation of the properties as a function of position in the foreshock, showing that transients close to the bow shock are associated with larger depletions in the plasma density and magnetic field magnitude, along with larger increases in the plasma temperature and the level of bulk flow deflection. Our measurements of the propagation velocities of cavitons and SHFAs agree with earlier studies, showing that the transients propagate sunward in the solar wind rest frame. We show that SHFAs have a greater solar wind rest frame propagation speed than cavitons, which is related to an increase in the magnetosonic speed near the bow shock.

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A statistical study into the spatial distribution and dawn-dusk asymmetry of dayside magnetosheath ion temperatures as a function of upstream solar wind conditions

Journal of Geophysical Research Space Physics ◽

10.1002/2014ja020734 ◽

2015 ◽

Vol 120 (4) ◽

pp. 2767-2782 ◽

Cited By ~ 24

Author(s):

A. P. Dimmock ◽

K. Nykyri ◽

H. Karimabadi ◽

A. Osmane ◽

T. I. Pulkkinen

Keyword(s):

Solar Wind ◽

Spatial Distribution ◽

Statistical Study ◽

Upstream Solar Wind

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Void structure of O+ ions in the inner magnetosphere observed by the Van Allen Probes

Journal of Geophysical Research Space Physics ◽

10.1002/2016ja023013 ◽

2016 ◽

Vol 121 (12) ◽

pp. 11,698-11,713 ◽

Cited By ~ 2

Author(s):

Y. Nakayama ◽

Y. Ebihara ◽

S. Ohtani ◽

M. Gkioulidou ◽

K. Takahashi ◽

...

Keyword(s):

Inner Magnetosphere ◽

Van Allen Probes ◽

Void Structure

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

10.5194/egusphere-egu2020-13703 ◽

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

<p>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.&#160;<br>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. &#160;</p>

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