Interplanetary Shock Impact Angles Control Magnetospheric ULF Wave Activity: Wave Amplitude, Frequency, and Power Spectra

2020 ◽  
Vol 47 (24) ◽  
Author(s):  
Denny M. Oliveira ◽  
Michael D. Hartinger ◽  
Zhonghua Xu ◽  
Eftyhia Zesta ◽  
Vyacheslav A. Pilipenko ◽  
...  
Keyword(s):  
Wave Amplitude ◽  
Power Spectra ◽  
Interplanetary Shock ◽  
Wave Activity ◽  
Ulf Wave ◽  
Shock Impact ◽  
Impact Angles ◽  
Activity Wave

scholarly journals How do interplanetary shock impact angles control the size of the geoeffective magnetosphere?

2019 ◽  
Vol 63 (1) ◽  
pp. 317-326 ◽  
Author(s):  
J.T. Rudd ◽  
D.M. Oliveira ◽  
A. Bhaskar ◽  
A.J. Halford
Keyword(s):  
Interplanetary Shock ◽  
Shock Impact ◽  
Impact Angles

scholarly journals Impact of interplanetary shock on the ULF wave activity: A case study of the storm sudden commencement on September 22, 1999

2001 ◽  
Vol 53 (12) ◽  
pp. 1177-1182 ◽  
Author(s):  
J. Kangas ◽  
J. Kultima ◽  
A. Guglielmi ◽  
A. Potapov ◽  
K. Hayashi
Keyword(s):  
Interplanetary Shock ◽  
Wave Activity ◽  
Sudden Commencement ◽  
Ulf Wave ◽  
Storm Sudden Commencement

scholarly journals Intermediate-<I>m</I> ULF waves generated by substorm injection: a case study

2010 ◽  
Vol 28 (8) ◽  
pp. 1499-1509 ◽  
Author(s):  
T. K. Yeoman ◽  
D. Yu. Klimushkin ◽  
P. N. Mager
Keyword(s):  
Phase Variation ◽  
Wave Activity ◽  
Wave Number ◽  
Ulf Wave ◽  
Azimuthal Wave ◽  
Azimuthal Wave Number ◽  
Source Particle ◽  
Phase Propagation ◽  
Field Lines

Abstract. A case study of SuperDARN observations of Pc5 Alfvén ULF wave activity generated in the immediate aftermath of a modest-intensity substorm expansion phase onset is presented. Observations from the Hankasalmi radar reveal that the wave had a period of 580 s and was characterized by an intermediate azimuthal wave number (m=13), with an eastwards phase propagation. It had a significant poloidal component and a rapid equatorward phase propagation (~62° per degree of latitude). The total equatorward phase variation over the wave signatures visible in the radar field-of-view exceeded the 180° associated with field line resonances. The wave activity is interpreted as being stimulated by recently-injected energetic particles. Specifically the wave is thought to arise from an eastward drifting cloud of energetic electrons in a similar fashion to recent theoretical suggestions (Mager and Klimushkin, 2008; Zolotukhina et al., 2008; Mager et al., 2009). The azimuthal wave number m is determined by the wave eigenfrequency and the drift velocity of the source particle population. To create such an intermediate-m wave, the injected particles must have rather high energies for a given L-shell, in comparison to previous observations of wave events with equatorward polarization. The wave period is somewhat longer than previous observations of equatorward-propagating events. This may well be a consequence of the wave occurring very shortly after the substorm expansion, on stretched near-midnight field lines characterised by longer eigenfrequencies than those involved in previous observations.

Electroencephalogram analysis of non-rapid eye movement sleep in rats

1988 ◽  
Vol 255 (1) ◽  
pp. R27-R37 ◽  
Author(s):  
L. Trachsel ◽  
I. Tobler ◽  
A. A. Borbely
Keyword(s):  
Eye Movement ◽  
Slow Wave ◽  
Power Spectra ◽  
Low Frequency ◽  
Wave Activity ◽  
Slow Wave Activity ◽  
Rapid Eye Movement ◽  
Rapid Eye Movement Sleep ◽  
Episode Duration ◽  
High Frequency Activity

Sleep states and power spectra of the electroencephalogram were determined for consecutive 4-s epochs during 24 h in rats that had been implanted with electrodes under deep pentobarbital anesthesia. The power spectra in non-rapid eye movement sleep (NREMS) showed marked trends: low-frequency activity (0.75-7.0 Hz) declined progressively throughout the 12-h light period (L) and remained low during most of the 12-h dark period (D); high-frequency activity (10.25-25.0 Hz) rose toward the end of L and reached a maximum at the beginning of D. Within a single NREMS episode (duration 0.5-5.0 min), slow-wave activity (0.75-4.0 Hz) increased progressively to a plateau level. The rise was approximated by a saturating exponential function: although the asymptote level of the function showed a prominent 24-h rhythm, the time constant remained relatively stable (approximately 40 s). After short interruptions of NREMS episodes, slow-wave activity rose more steeply than after long interruptions. The marked 24-h variation of maximum slow-wave activity within NREMS episodes may reflect the level of a homeostatic sleep process.

scholarly journals Solar wind influence on Pc4 and Pc5 ULF wave activity in the inner magnetosphere

2010 ◽  
Vol 115 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
W. Liu ◽  
T. E. Sarris ◽  
X. Li ◽  
R. Ergun ◽  
V. Angelopoulos ◽  
...  
Keyword(s):  
Solar Wind ◽  
Wave Activity ◽  
Inner Magnetosphere ◽  
Ulf Wave ◽  
Wind Influence

scholarly journals The Pulsating Magnetosphere at Jupiter

2020 ◽  
Author(s):  
Harry Manners ◽  
Adam Masters
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Dynamic Pressure ◽  
Wave Spectrum ◽  
Low Frequency ◽  
Global Scale ◽  
Wave Activity ◽  
Ulf Waves ◽  
Ulf Wave ◽  
Wide Range

&lt;p&gt;The magnetosphere of Jupiter is the largest planetary magnetosphere in the solar system, and plays host to internal dynamics that remain, in many ways, mysterious. Prominent among these mysteries are the ultra-low-frequency (&lt;strong&gt;ULF&lt;/strong&gt;) pulses ubiquitous in this system. Pulsations in the electromagnetic emissions, magnetic field and flux of energetic particles have been observed for decades, with little to indicate the source mechanism. While ULF waves have been observed in the magnetospheres of all the magnetized planets, the magnetospheric environment at Jupiter seems particularly conducive to the emergence of ULF waves over a wide range of periods (1-100+ minutes). This is mainly due to the high variability of the system on a global scale: internal plasma sources and a powerful intrinsic magnetic field produce a highly-compressible magnetospheric cavity, which can be reduced to a size significantly smaller than its nominal expanded state by variations in the dynamic pressure of the solar wind. Compressive fronts in the solar wind, turbulent surface interactions on the magnetopause and internal plasma processes can also all lead to ULF wave activity inside the magnetosphere.&lt;/p&gt;&lt;p&gt;To gain the first comprehensive view of ULF waves in the Jovian system, we have performed a heritage survey of magnetic field data measured by six spacecraft that visited the magnetosphere (Galileo, Ulysses, Voyager 1 &amp; 2 and Pioneer 10 &amp; 11). We found several-hundred wave events consisting of wave packets parallel or transverse to the mean magnetic field, interpreted as fast-mode or Alfv&amp;#233;nic MHD wave activity, respectively. Parallel and transverse events were often coincident in space and time, which may be evidence of global Alfv&amp;#233;nic resonances of the magnetic field known as field-line-resonances. We found that 15-, 30- and 40-minute periods dominate the Jovian ULF wave spectrum, in agreement with the dominant &amp;#8220;magic frequencies&amp;#8221; often reported in existing literature.&lt;/p&gt;&lt;p&gt;We will discuss potential driving mechanisms as informed by the results of the heritage survey, how this in turn affects our understanding of energy transfer in the magnetosphere, and potential investigations to be made using data from the JUNO spacecraft. We will also discuss the potential for multiple resonant cavities, and how the resonance modes of the Jovian magnetosphere may differ from those of the other magnetized planets.&lt;/p&gt;

scholarly journals The ionospheric response during an interval of Pc5 ULF wave activity

2000 ◽  
Vol 18 (2) ◽  
pp. 0257-0261
Author(s):  
M. Lester ◽  
J. A. Davies ◽  
T. K. Yeoman
Keyword(s):  
Wave Activity ◽  
Ionospheric Response ◽  
Ulf Wave

scholarly journals Features of Nightside ULF Wave Activity in the Ionosphere

2019 ◽  
Vol 124 (11) ◽  
pp. 9203-9213 ◽  
Author(s):  
X.Y. Ouyang ◽  
J. Bortnik ◽  
J. Ren ◽  
J.J. Berthelier
Keyword(s):  
Wave Activity ◽  
Ulf Wave

scholarly journals The 8 June 2000 ULF wave activity: A case study

2012 ◽  
Vol 117 (A2) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. Piersanti ◽  
U. Villante ◽  
C. Waters ◽  
I. Coco
Keyword(s):  
Wave Activity ◽  
Ulf Wave

Long periods of the ULF wave activity in the Earth's magnetotail lobes

1996 ◽  
Vol 18 (8) ◽  
pp. 55-58 ◽  
Author(s):  
B Nikutowski ◽  
J Büchner ◽  
S Klimov ◽  
S Romanov ◽  
A Petrukovich ◽  
...  
Keyword(s):  
Wave Activity ◽  
Ulf Wave
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