Journal article
EMIC Wave Properties Associated With and Without Injections in The Inner Magnetosphere
Journal of geophysical research. Space physics, Vol.124(3), pp.2029-2045
03/01/2019
DOI: 10.1029/2018JA026279
Abstract
To understand the generation and propagation processes of electromagnetic ion cyclotron (EMIC) waves under different geomagnetic conditions in the inner magnetosphere, we performed a statistical study of EMIC wave properties observed by the Van Allen Probes from February 2013 to December 2016. We divided EMIC waves into two groups: those associated with and those occurring without injections observed by the Geostationary Operational Environmental Satellites (GOES-13 and GOES-15). We found that the EMIC wave polarization sense epsilon increased and the normalized frequency X decreased with increasing vertical bar MLAT vertical bar. Inside the plasmasphere, He+ EMIC waves were predominantly observed with left-hand polarization (epsilon < -0.3) and higher wave normal angles (theta(k) = 30-40 degrees ). Those associated with injections showed the most intense wave power at 14-16 MLT, compared to periods without injections when these waves exhibit a similar wave power but on the dayside. H+ EMIC waves were predominantly observed outside the plasmasphere on the dayside and showed a mixture of left-hand and linear polarizations (epsilon = -0.3-0.0) with lower wave normal angles (theta(k) = 20-30 degrees ) regardless of injections. Moreover, H+ EMIC waves were accompanied by a solar wind dynamic pressure enhancement (Delta Psw = 0.5 nPa). From these observations, we suggest that hot injected plasma contributes to the generation of intense He+ EMIC waves in the afternoon sector. A mixture of expanding cold plasmaspheric ions and coexisting hot ring current ions acts as the free energy source for He+ EMIC waves on the dayside during quiet times. Solar wind dynamic pressure enhancements are likely the major driver of H+ EMIC waves outside the plasmasphere.
Details
- Title: Subtitle
- EMIC Wave Properties Associated With and Without Injections in The Inner Magnetosphere
- Creators
- C-W Jun - NOAA Oceanic and Atmospheric ResearchC. Yue - Univ Calif Los Angeles, Atmospher & Ocean Sci, Los Angeles, CA 90095 USAJ. Bortnik - University of California, Los AngelesL. R. Lyons - NOAA Oceanic and Atmospheric ResearchY. Nishimura - Boston UniversityC. Kletzing - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.124(3), pp.2029-2045
- Publisher
- Amer Geophysical Union
- DOI
- 10.1029/2018JA026279
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 17
- Grant note
- NNX16AG21G / NASA HTIDeS NNX14AN85G / NASA LWS Grant NNX16AF76G / NASA; National Aeronautics & Space Administration (NASA)
- Language
- English
- Date published
- 03/01/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984428771902771
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