Found 17 entries in the Bibliography.

Showing entries from 1 through 17


Whistler Mode Quasiperiodic Emissions: Contrasting Van Allen Probes and DEMETER Occurrence Rates

Abstract Quasiperiodic emissions are magnetospheric whistler mode waves at frequencies between about 0.5 and 4 kHz which exhibit a nearly periodic time modulation of the wave intensity. We use large data sets of events observed by the Van Allen Probes in the equatorial region at larger radial distances and by the low-altitude DEMETER spacecraft. While Van Allen Probes observe the events at all local times and longitudes, DEMETER observations are limited nearly exclusively to the daytime and significantly less frequent at the ...

Němec, F.; Santolik, O.; Hospodarsky, G.; Hajoš, M.; Demekhov, A.; Kurth, W.; Parrot, M.; Hartley, D.;

YEAR: 2020     DOI: 10.1029/2020JA027918

quasiperiodic emissions; QP emissions; DEMETER; RBSP; Van Allen Probes

Localization of the Source of Quasiperiodic VLF Emissions in the Magnetosphere by Using Simultaneous Ground and Space Observations: A Case Study

Abstract We study quasiperiodic very low frequency (VLF) emissions observed simultaneously by Van Allen Probes spacecraft and Kannuslehto and Lovozero ground-based stations on 25 December 2015. Both Van Allen Probes A and B detected quasiperiodic emissions, probably originated from a common source, and observed on the ground. In order to locate possible regions of wave generation, we analyze wave-normal angles with respect to the geomagnetic field, Poynting flux direction, and cyclotron instability growth rate calculated by ...

Demekhov, A.; Titova, E.; Maninnen, J.; Pasmanik, D.; Lubchich, A.; Santolik, O.; Larchenko, A.; Nikitenko, A.; Turunen, T.;

YEAR: 2020     DOI: 10.1029/2020JA027776

quasiperiodic VLF emissions; Cyclotron instability; wave propagation; Magnetosphere; whistler mode waves; Van Allen Probes

A Multi-Instrument Approach to Determining the Source-Region Extent of EEP-Driving EMIC Waves

Abstract Recent years have seen debate regarding the ability of electromagnetic ion cyclotron (EMIC) waves to drive EEP (energetic electron precipitation) into the Earth s atmosphere. Questions still remain regarding the energies and rates at which these waves are able to interact with electrons. Many studies have attempted to characterize these interactions using simulations; however, these are limited by a lack of precise information regarding the spatial scale size of EMIC activity regions. In this study we examine a fort ...

Hendry, A.; Santolik, O.; Miyoshi, Y.; Matsuoka, A.; Rodger, C.; Clilverd, M.; Kletzing, C.; Shoji, M.; Shinohara, I.;

YEAR: 2020     DOI: 10.1029/2019GL086599

EMIC waves; electron precipitation; subionospheric VLF; Van Allen Probes; AARDDVARK; Arase

Fine Harmonic Structure of Equatorial Noise with a Quasiperiodic Modulation

Abstract Equatorial noise emissions (fast magnetosonic waves) are electromagnetic waves observed routinely in the equatorial region of the inner magnetosphere. They propagate with wave vectors nearly perpendicular to the ambient magnetic field; that is, they are limited to frequencies below the lower hybrid frequency. The waves are generated by instabilities of ring-like proton distribution functions, which result in their fine harmonic structure with intensity maxima close to harmonics of the proton cyclotron frequency in t ...

Němec, F.; Tomori, A.; Santolik, O.; Boardsen, S.; Hospodarsky, G.; Kurth, W.; Pickett, J.; Kletzing, C.;

YEAR: 2020     DOI: 10.1029/2019JA027509

equatorial noise; Fast Magnetosonic Waves; quasiperiodic modulation; Van Allen Probes


Lightning Contribution to Overall Whistler Mode Wave Intensities in the Plasmasphere

Electromagnetic waves generated by lightning propagate into the plasmasphere as dispersed whistlers. They can therefore influence the overall wave intensity in space, which, in turn, is important for dynamics of the Van Allen radiation belts. We analyze spacecraft measurements in low-Earth orbit as well as in high-altitude equatorial region, together with a ground-based estimate of lightning activity. We accumulate wave intensities when the spacecraft are magnetically connected to thunderstorms and compare them with measurem ...

ahlava, J.; emec, F.; Santolik, O.; a, Kolma\v; Hospodarsky, G.; Parrot, M.; Kurth, W.; Kletzing, C.;

YEAR: 2019     DOI: 10.1029/2019GL083918

DEMETER; Lightning; Van Allen Probes; whistler mode; WWLLN

EMIC waves converted from equatorial noise due to M/Q=2 ions in the plasmasphere: Observations from Van Allen Probes and Arase

Equatorial noise (EN) emissions are observed inside and outside the plasmapause. EN emissions are referred to as magnetosonic mode waves. Using data from Van Allen Probes and Arase, we found conversion from EN emissions to electromagnetic ion cyclotron (EMIC) waves in the plasmasphere and in the topside ionosphere. A low frequency part of EN emissions becomes EMIC waves through branch splitting of EN emissions, and the mode conversion from EN to EMIC waves occurs around the frequency of M/Q=2 (deuteron and/or alpha particles ...

Miyoshi, Y.; Matsuda, S.; Kurita, S.; Nomura, K.; Keika, K.; Shoji, M.; Kitamura, N.; Kasahara, Y.; Matsuoka, A.; Shinohara, I.; Shiokawa, K.; Machida, S.; Santolik, O.; Boardsen, S.A.; Horne, R.B.; Wygant, J.F.;

YEAR: 2019     DOI: 10.1029/2019GL083024

Arase; EMIC; M/Q=2 ions; Magnetsonic waves; plasmasphere; Van Allen Probes


Observations Directly Linking Relativistic Electron Microbursts to Whistler Mode Chorus: Van Allen Probes and FIREBIRD II

We present observations that provide the strongest evidence yet that discrete whistler mode chorus packets cause relativistic electron microbursts. On 20 January 2016 near 1944 UT the low Earth orbiting CubeSat Focused Investigations of Relativistic Electron Bursts: Intensity, Range, and Dynamics (FIREBIRD II) observed energetic microbursts (near L = 5.6 and MLT = 10.5) from its lower limit of 220 keV, to 1 MeV. In the outer radiation belt and magnetically conjugate, Van Allen Probe A observed rising-tone, lower band chorus ...

Breneman, A.; Crew, A.; Sample, J.; Klumpar, D.; Johnson, A.; Agapitov, O.; Shumko, M.; Turner, D.; Santolik, O.; Wygant, J.; Cattell, C.; Thaller, S.; Blake, B.; Spence, H.; Kletzing, C.;

YEAR: 2017     DOI: 10.1002/2017GL075001

Chorus; conjunction; FIREBIRD; microburst; Van Allen Probes

Examining coherency scales, substructure, and propagation of whistler-mode chorus elements with Magnetospheric Multiscale (MMS)

Whistler-mode chorus waves are a naturally occurring electromagnetic emission observed in Earth\textquoterights magnetosphere. Here, for the first time, data from NASA\textquoterights Magnetospheric Multiscale (MMS) mission were used to analyze chorus waves in detail, including the calculation of chorus wave normal vectors, k. A case study was examined from a period of substorm activity around the time of a conjunction between the MMS constellation and NASA\textquoterights Van Allen Probes mission on 07 April 2016. Chorus wa ...

Turner, D.; Lee, J.; Claudepierre, S.; Fennell, J.; Blake, J.; Jaynes, A.; Leonard, T.; Wilder, F.; Ergun, R.; Baker, D.; Cohen, I.; Mauk, B.; Strangeway, R.; Hartley, D.; Kletzing, C.; Breuillard, H.; Le Contel, O.; Khotyaintsev, Yu; Torbert, R.; Allen, R.; Burch, J.; Santolik, O.;

YEAR: 2017     DOI: 10.1002/2017JA024474

chorus waves; inner magnetosphere; Magnetospheric multiscale; MMS; Radiation belts; Van Allen Probes


New Chorus Wave Properties Near the Equator from Van Allen Probes Wave Observations

The chorus wave properties are evaluated using Van Allen Probes data in the Earth\textquoterights equatorial magnetosphere. Two distinct modes of lower band chorus are identified: a quasi-parallel mode and a quasi-electrostatic mode, whose wave normal direction is close to the resonance cone. Statistical results indicate that the quasi-electrostatic (quasi-parallel) mode preferentially occurs during relatively quiet (disturbed) geomagnetic activity at lower (higher) L shells. Although the magnetic intensity of the quasi-elec ...

Li, W.; Santolik, O.; Bortnik, J.; Thorne, R.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2016     DOI: 10.1002/2016GL068780

Chorus wave; oblique; quasi-electrostatic; quasi-parallel; Van Allen Probes; wave normal angles


Identification of the source of quasiperiodic VLF emissions using ground-based and Van Allen Probes satellite observations

We report on simultaneous spacecraft and ground-based observations of quasiperiodic VLF emissions and related energetic-electron dynamics. Quasiperiodic emissions in the frequency range 2\textendash6 kHz were observed during a substorm on 25 January 2013 by Van Allen Probe-A and a ground-based station in the Northern Finland. The spacecraft detected the VLF signals near the geomagnetic equator in the night sector at L = 3.0\textendash4.2 when it was inside the plasmasphere. During the satellite motion toward higher latitudes ...

Titova, E.; Kozelov, B.; Demekhov, A.; Manninen, J.; Santolik, O.; Kletzing, C.; Reeves, G.;

YEAR: 2015     DOI: 10.1002/grl.v42.1510.1002/2015GL064911

energetic electrons; quasiperiodic emissions; Van Allen Probes; VLF waves

Equatorial noise emissions with quasiperiodic modulation of wave intensity

Equatorial noise (EN) emissions are electromagnetic wave events at frequencies between the proton cyclotron frequency and the lower hybrid frequency observed in the equatorial region of the inner magnetosphere. They propagate nearly perpendicular to the ambient magnetic field, and they exhibit a harmonic line structure characteristic of the proton cyclotron frequency in the source region. However, they were generally believed to be continuous in time. We investigate more than 2000 EN events observed by the Spatio-Temporal An ...

emec, F.; Santolik, O.; a, Hrb\; Pickett, J.; Cornilleau-Wehrlin, N.;

YEAR: 2015     DOI: 10.1002/2014JA020816

equatorial noise; magnetosonic waves; quasiperiodic modulation

Intensities and spatiotemporal variability of equatorial noise emissions observed by the Cluster spacecraft

Equatorial noise (EN) emissions are electromagnetic waves observed in the equatorial region of the inner magnetosphere at frequencies between the proton cyclotron frequency and the lower hybrid frequency. We present the analysis of 2229 EN events identified in the Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment data of the Cluster spacecraft during the years 2001\textendash2010. EN emissions are distinguished using the polarization analysis, and their intensity is determined based on the evaluation of the P ...

emec, F.; Santolik, O.; a, Hrb\; Cornilleau-Wehrlin, N.;

YEAR: 2015     DOI: 10.1002/2014JA020814

equatorial noise; magnetosonic waves

Energetic electron precipitation associated with pulsating aurora: EISCAT and Van Allen Probe observations

Pulsating auroras show quasi-periodic intensity modulations caused by the precipitation of energetic electrons of the order of tens of keV. It is expected theoretically that not only these electrons but also sub-relativistic/relativistic electrons precipitate simultaneously into the ionosphere owing to whistler-mode wave\textendashparticle interactions. The height-resolved electron density profile was observed with the European Incoherent Scatter (EISCAT) Troms\o VHF radar on 17 November 2012. Electron density enhancements w ...

Miyoshi, Y.; Oyama, S.; Saito, S.; Kurita, S.; Fujiwara, H.; Kataoka, R.; Ebihara, Y.; Kletzing, C.; Reeves, G.; Santolik, O.; Clilverd, M.; Rodger, C.; Turunen, E.; Tsuchiya, F.;

YEAR: 2015     DOI: 10.1002/2014JA020690

EISCAT; pitch angle scattering; pulsating aurora; Van Allen Probes

Systematic analysis of occurrence of equatorial noise emissions using 10 years of data from the Cluster mission

We report results of a systematic analysis of equatorial noise (EN) emissions which are also known as fast magnetosonic waves. EN occurs in the vicinity of the geomagnetic equator at frequencies between the local proton cyclotron frequency and the lower hybrid frequency. Our analysis is based on the data collected by the Spatio-Temporal Analysis of Field Fluctuations\textendashSpectrum Analyzer instruments on board the four Cluster spacecraft. The data set covers the period from January 2001 to December 2010. We have develop ...

a, Hrb\; Santolik, O.; emec, F.; a, Mac\; Cornilleau-Wehrlin, N.;

YEAR: 2015     DOI: 10.1002/2014JA020268

equatorial noise; magnetosonic waves; plasmasphere; Radiation belts


Statistical properties of wave vector directions of whistler-mode waves in the radiation belts based on measurements of the Van Allen probes and Cluster missions

Wave-particle interactions in the Earth\textquoterights Van Allen radiation belts are known to be an efficient process of the exchange of energy between different particle populations, including the energetic radiation belt particles. The whistler mode waves, especially chorus, can control the radiation belt dynamics via linear or nonlinear interactions with both the energetic radiation belt electrons and lower energy electron populations. Wave vector directions are a very important parameter of these wave-particle interacti ...

Santolik, O.; Hospodarsky, G.; Kurth, W.; Averkamp, T.; Kletzing, C.; Cornilleau-Wehrlin, N.;

YEAR: 2014     DOI: 10.1109/URSIGASS.2014.6929880

Atmospheric measurements; Magnetic field measurement; Van Allen Probes

Fine structure of large-amplitude chorus wave packets

Whistler mode chorus waves in the outer Van Allen belt can have consequences for acceleration of relativistic electrons through wave-particle interactions. New multicomponent waveform measurements have been collected by the Van Allen Probes Electric and Magnetic Field Instrument Suite and Integrated Science\textquoterights Waves instrument. We detect fine structure of chorus elements with peak instantaneous amplitudes of a few hundred picotesla but exceptionally reaching up to 3 nT, i.e., more than 1\% of the background magn ...

Santolik, O.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Bounds, S.;

YEAR: 2014     DOI: 10.1002/2013GL058889

Van Allen Probes


The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on RBSP

The Electric and Magnetic Field Instrument and Integrated Science (EMFISIS) investigation on the NASA Radiation Belt Storm Probes (now named the Van Allen Probes) mission provides key wave and very low frequency magnetic field measurements to understand radiation belt acceleration, loss, and transport. The key science objectives and the contribution that EMFISIS makes to providing measurements as well as theory and modeling are described. The key components of the instruments suite, both electronics and sensors, including ke ...

Kletzing, C.; Kurth, W.; Acuna, M.; MacDowall, R.; Torbert, R.; Averkamp, T.; Bodet, D.; Bounds, S.; Chutter, M.; Connerney, J.; Crawford, D.; Dolan, J.; Dvorsky, R.; Hospodarsky, G.; Howard, J.; Jordanova, V.; Johnson, R.; Kirchner, D.; Mokrzycki, B.; Needell, G.; Odom, J.; Mark, D.; Pfaff, R.; Phillips, J.; Piker, C.; Remington, S.; Rowland, D.; Santolik, O.; Schnurr, R.; Sheppard, D.; Smith, C.; Thorne, R.; Tyler, J.;

YEAR: 2013     DOI: 10.1007/s11214-013-9993-6

RBSP; Van Allen Probes