NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Cluster Observations of Non-Time Continuous Magnetosonic WavesEquatorial magnetosonic waves are normally observed as temporally continuous sets of emissions lasting from minutes to hours. Recent observations, however, have shown that this is not always the case. Using Cluster data, this study identifies two distinct forms of these non temporally continuous use missions. The first, referred to as rising tone emissions, are characterized by the systematic onset of wave activity at increasing proton gyroharmonic frequencies. Sets of harmonic emissions (emission elements)are observed to occur periodically in the region +/- 10 off the geomagnetic equator. The sweep rate of these emissions maximizes at the geomagnetic equator. In addition, the ellipticity and propagation direction also change systematically as Cluster crosses the geomagnetic equator. It is shown that the observed frequency sweep rate is unlikely to result from the sideband instability related to nonlinear trapping of suprathermal protons in the wave field. The second form of emissions is characterized by the simultaneous onset of activity across a range of harmonic frequencies. These waves are observed at irregular intervals. Their occurrence correlates with changes in the spacecraft potential, a measurement that is used as a proxy for electron density. Thus, these waves appear to be trapped within regions of localized enhancement of the electron density.
Document ID
20170003122
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Walker, Simon N.
(Sheffield Univ. United Kingdom)
Demekhov, Andrei G.
(Academy of Sciences (USSR) Murmansk, Russian Federation)
Boardsen, Scott A.
(Maryland Univ. Baltimore County Baltimore, MD, United States)
Ganushkina, Natalia Y.
(Finnish Meteorological Inst. Helsinki, Finland)
Sibeck, David G.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Balikhin, Michael A.
(Sheffield Univ. United Kingdom)
Date Acquired
April 6, 2017
Publication Date
October 18, 2016
Publication Information
Publication: Journal of Geophysical Research: Space Physics
Publisher: AGU
Volume: 121
Issue: 10
e-ISSN: 2169-9402
Subject Category
Plasma Physics
Geophysics
Report/Patent Number
GSFC-E-DAA-TN41092
Funding Number(s)
CONTRACT_GRANT: NAS5-01072
CONTRACT_GRANT: NNG11PL02A
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available