scholarly journals Electromagnetic power of lightning superbolts from Earth to space

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J.-F. Ripoll ◽  
T. Farges ◽  
D. M. Malaspina ◽  
G. S. Cunningham ◽  
E. H. Lay ◽  
...  
Keyword(s):  
Low Frequency ◽  
Optical Emission ◽  
High Energy ◽  
Very Low Frequency ◽  
Electromagnetic Power ◽  
Power Spectral ◽  
High Energy Tail ◽  
Van Allen Probes ◽  
Long Time ◽  
Low Frequency Waves

AbstractLightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space. Superbolt events occurred in 2010-2018 could be localized by extracting the high energy tail of the lightning stroke signals measured by the very low frequency ground stations of the World-Wide Lightning Location Network. Here, we report electromagnetic observations of superbolts from space using Van Allen Probes satellite measurements, and ground measurements, and with two events measured both from ground and space. From burst-triggered measurements, we compute electric and magnetic power spectral density for very low frequency waves driven by superbolts, both on Earth and transmitted into space, demonstrating that superbolts transmit 10-1000 times more powerful very low frequency waves into space than typical strokes and revealing that their extreme nature is observed in space. We find several properties of superbolts that notably differ from most lightning flashes; a more symmetric first ground-wave peak due to a longer rise time, larger peak current, weaker decay of electromagnetic power density in space with distance, and a power mostly confined in the very low frequency range. Their signal is absent in space during day times and is received with a long-time delay on the Van Allen Probes. These results have implications for our understanding of lightning and superbolts, for ionosphere-magnetosphere wave transmission, wave propagation in space, and remote sensing of extreme events.

scholarly journals Very low frequency waves in the heliosphere: Ulysses observations

1998 ◽  
Vol 103 (A6) ◽  
pp. 12023-12035 ◽  
Author(s):  
Naiguo Lin ◽  
P. J. Kellogg ◽  
R. J. MacDowall ◽  
E. E. Scime ◽  
A. Balogh ◽  
...  
Keyword(s):  
Low Frequency ◽  
Very Low Frequency ◽  
Low Frequency Waves

scholarly journals Van Allen Probes observation of localized drift resonance between poloidal mode ultra‐low frequency waves and 60 keV electrons

2013 ◽  
Vol 40 (17) ◽  
pp. 4491-4497 ◽  
Author(s):  
S. G. Claudepierre ◽  
I. R. Mann ◽  
K. Takahashi ◽  
J. F. Fennell ◽  
M. K. Hudson ◽  
...  
Keyword(s):  
Low Frequency ◽  
Van Allen Probes ◽  
Low Frequency Waves

scholarly journals Cooling-Evoked Hemodynamic Perturbations Facilitate Sympathetic Activity with Subsequent Myogenic Vascular Oscillations via Alpha2-Adrenergic Receptors

2017 ◽  
pp. 449-457 ◽  
Author(s):  
Y.-H. LIN ◽  
Y.-P. LIU ◽  
Y.-C. LIN ◽  
P.-L. LEE ◽  
C.-S. TUNG
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pressor Response ◽  
Low Frequency ◽  
Power Spectral Analysis ◽  
Sprague Dawley ◽  
Cold Stimulation ◽  
Very Low Frequency ◽  
Power Spectral ◽  
Sprague Dawley Rats

This study extends our previous work by examining the effects of alpha2-adrenoceptors under cold stimulation involving the increase of myogenic vascular oscillations as increases of very-low-frequency and low-frequency of the blood pressure variability. Forty-eight adult male Sprague-Dawley rats were randomly divided into four groups: vehicle; yohimbine; hexamethonium+yohimbine; guanethidine+yohimbine. Systolic blood pressure, heart rate, power spectral analysis of spontaneous blood pressure and heart rate variability and spectral coherence at very-low-frequency (0.02 to 0.2 Hz), low-frequency (0.2 to 0.6 Hz), and high-frequency (0.6 to 3.0 Hz) regions were monitored using telemetry. Key findings are as follows: 1) Cooling-induced pressor response was attenuated by yohimbine and further attenuated by hexamethonium+yohimbine and guanethidine+yohimbine, 2) Cooling-induced tachycardia response of yohimbine was attenuated by hexame-thonium+yohimbine and guanethidine+yohimbine, 3) Different patterns of power spectrum reaction and coherence value compared hexamethonium+yohimbine and guanethi-dine+yohimbine to yohimbine alone under cold stimulation. The results suggest that sympathetic activation of the postsynaptic alpha2-adrenoceptors causes vasoconstriction and heightening myogenic vascular oscillations, in turn, may increase blood flow to prevent tissue damage under stressful cooling challenge.

Investigation of the Dynamics of Copper Plasma Generated from a Laser-Ablated Target Using Optical Emission Analysis

1997 ◽  
Vol 51 (6) ◽  
pp. 883-888 ◽  
Author(s):  
J. D. Wu ◽  
Q. Pan ◽  
S. C. Chen
Keyword(s):  
Laser Ablation ◽  
Optical Emission ◽  
High Energy ◽  
Emission Analysis ◽  
Spatially Resolved ◽  
Initial Stage ◽  
Long Time ◽  
Higher Temperature ◽  
Spatial Behaviors ◽  
Copper Plasma

Spatially resolved and integrated spectroscopies, especially temporal emission profile measurements, were used to examine the plume emissions associated with copper plasma generated by 308-nm excimer laser ablation at reduced pressures (< 1.0 × 10−1 Pa), by which the composition and dynamics of the plasma were investigated. It is found that, even for the same emitting species, the temporal and spatial behaviors of the emissions originating from different transitions can be very different. Three types of emission lines are clearly evident, which reveal the characteristics of the plasma. The plasma forms as a result of laser ablation and evolves from breakdown of the ablation-created copper vapor to electron-collisional expansion dynamics. At the initial stage, the plasma involves a large amount of Cu(II) and high energy-excited Cu(I) species, and then evolves to consist mainly of low energy-excited Cu(I) species. The results also show that the plasma maintains higher temperature for a quite a long time, and cool electron-impacting excitations determine the plasma behavior while it expands far away from the target.

scholarly journals The electron energy distribution during HF pumping, a picture painted with all colors

2005 ◽  
Vol 23 (5) ◽  
pp. 1747-1754 ◽  
Author(s):  
B. Gustavsson ◽  
T. Sergienko ◽  
M. J. Kosch ◽  
M. T. Rietveld ◽  
B. U. E. Brändström ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Electron Temperature ◽  
Electron Energy ◽  
Optical Emission ◽  
Electron Excitation ◽  
High Energy ◽  
Electron Energy Distribution ◽  
Ion Temperature ◽  
Ionospheric Physics ◽  
High Energy Tail

Abstract. The shape of the electron energy distribution has long been a central question in the field of high-frequency radio-induced optical emission experiments. This report presents estimates of the electron energy distribution function, fe(E), from 0 to 60 eV, based on optical multi-wavelength (6300, 5577, 8446, 4278Å) data and 930-MHz incoherent scatter radar measurements of ion temperature, electron temperature and electron concentration. According to our estimate, the electron energy distribution has a depression at around 2 eV, probably caused by electron excitation of vibrational states in N2, and a high energy tail that is clearly supra-thermal. The temporal evolution of the emissions indicates that the electron temperature still plays an important role in providing electrons with energies close to 2 eV. At the higher energies the electron energy distribution has a non-thermal tail. Keywords. Active experiments; Ionosphere atmosphere interaction; Ionospheric physics

scholarly journals Identification and classification of very low frequency waves on a coral reef flat

2016 ◽  
Vol 121 (10) ◽  
pp. 7560-7574 ◽  
Author(s):  
Matthijs Gawehn ◽  
Ap van Dongeren ◽  
Arnold van Rooijen ◽  
Curt D. Storlazzi ◽  
Olivia M. Cheriton ◽  
...  
Keyword(s):  
Coral Reef ◽  
Reef Flat ◽  
Low Frequency ◽  
Very Low Frequency ◽  
Low Frequency Waves
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