DEMETER observations of bursty MF emissions and their relation to ground-level auroral MF burst

• Published in: Journal of Geophysical Research: Space Physics
• Main Authors: Broughton, M.C., Labelle, J, Parrot, Michel
• Other Authors: Department of Physics and Astronomy Hanover, Dartmouth College Hanover, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales Paris (CNES), National Science Foundation grant NSF AGS-1147699
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDU]Sciences of the Universe [physics]; Langmuir; Churchill
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-01174023; https://hal-insu.archives-ouvertes.fr/insu-01174023/document; https://hal-insu.archives-ouvertes.fr/insu-01174023/file/jgra51420.pdf; https://doi.org/10.1002/2014JA020410

International audience A survey of medium frequency (MF) electric field data from selected orbits of the Detectionof Electro-Magnetic Emissions Transmitted from Earthquakes (DEMETER) spacecraft reveals 68 examples ofa new type of bursty MF emissions occurring at high latitudes associated with auroral phenomena. Theseresemble auroral MF burst, a natural radio emission observed at ground level near local substorm onsets.Similar to MF burst, the bursty MF waves observed by DEMETER have broadband, impulsive frequencystructure covering 1.5–3.0 MHz, amplitudes of 50–100 μV/m, an overall occurrence rate of ∼0.76% withhigher occurrence during active times, and strong correlation with auroral hiss. The magnetic local timedistribution of the MF waves observed by DEMETER shows peak occurrence rate near 18 MLT, somewhatearlier than the equivalent peak in the occurrence rate of ground level MF burst, though propagation effectsand differences in the latitudes sampled by the two techniques may explain this discrepancy. Analysis ofsolar wind and SuperMAG data suggests that while the bursty MF waves observed by DEMETER areassociated with enhanced auroral activity, their coincidence with substorm onset may not be as exact asthat of ground level MF burst. One conjunction occurs in which MF burst is observed at Churchill, Manitoba,within 8 min of MF emissions detected by DEMETER on field lines approximately 1000 km southeast ofChurchill. These observations may plausibly be associated with the same auroral event detected by groundlevel magnetometers at several Canadian observatories. Although it is uncertain, the balance of theevidence suggests that the bursty MF waves observed with DEMETER are the same phenomenon as theground level MF burst. Hence, theories of MF burst generation in the ionosphere, such as beam-generatedLangmuir waves excited over a range of altitudes or strong Langmuir turbulence generating a range offrequencies within a narrow altitude range, need to be revisited to see whether they predict in situ detectionof ...