Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study

C. A Cattell; A. W Breneman; S. A Thaller; J. R Wygant; C. A Kletzing; W. S Kurth

doi:10.1002/2015GL065565

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Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study

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Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study

C. A Cattell, A. W Breneman, S. A Thaller, J. R Wygant, C. A Kletzing and W. S Kurth

Geophysical research letters, Vol.42(18), pp.7273-7281

09/28/2015

DOI: 10.1002/2015GL065565

PMCID: PMC5014236

PMID: 27667871

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Abstract

We show the first evidence for locally excited chorus at frequencies below 0.1 f ce (electron cyclotron frequency) in the outer radiation belt. A statistical study of chorus during geomagnetic storms observed by the Van Allen Probes found that frequencies are often dramatically lower than expected. The frequency at peak power suddenly stops tracking the equatorial 0.5 f ce and f / f ce decreases rapidly, often to frequencies well below 0.1 f ce (in situ and mapped to equator). These very low frequency waves are observed both when the satellites are close to the equatorial plane and at higher magnetic latitudes. Poynting flux is consistent with generation at the equator. Wave amplitudes can be up to 20 to 40 mV/m and 2 to 4 nT. We conclude that conditions during moderate to large storms can excite unusually low frequency chorus, which is resonant with more energetic electrons than typical chorus, with critical implications for understanding radiation belt evolution. Chorus can be locally excited below 0.1 fce down to flh in outer radiation belt Frequency rapidly decreases below usual values, thus resonating with more energetic electrons Usually seen near minimum in Dst with implications for radiation belt evolution

chorus

Ionosphere

Kinetic Waves and Instabilities

Magnetic Storms

Magnetic Storms and Substorms

Magnetospheric Physics

Natural Hazards

outer radiation belt

Plasma Waves and Instabilities

Radiation Belts

Research Letter

Research Letters

Space Plasma Physics

Space Weather

Details

Title: Subtitle: Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study
Creators: C. A Cattell - University of Minnesota
A. W Breneman - University of Minnesota
S. A Thaller - University of Minnesota
J. R Wygant - University of Minnesota
C. A Kletzing - University of Iowa
W. S Kurth - University of Iowa
Resource Type: Journal article
Publication Details: Geophysical research letters, Vol.42(18), pp.7273-7281
DOI: 10.1002/2015GL065565
PMID: 27667871
PMCID: PMC5014236
NLM abbreviation: Geophys Res Lett
ISSN: 0094-8276
eISSN: 1944-8007
Publisher: John Wiley and Sons Inc
Grant note: NAS5‐01072 / NASA Prime APL NAS5‐01072 / NASA 921647 / JHU/APL
Alternative title: UNUSUALLY LOW FREQUENCY CHORUS AT RBSP
Language: English
Date published: 09/28/2015
Academic Unit: Physics and Astronomy
Record Identifier: 9984199799202771

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