New Observations of the Non-Thermal Continuum Radiation at the Plasmapause

Scott A. Boardsen (1), James L. Green (2),  Kozo Hashimoto (3), 
Hiroshi Matsumoto (3),  Bill R. Sandel (4), and Bodo W. Reinishch (5)

(1) L3 Communications Government Services, Inc., Code 630 NASA Goddard Space
Flight Center, Greenbelt, MD 20771, United States 
(2) NASA/GSFC, NASA Goddard Space Flight Center Greenbelt, MD 20771, Greenbelt, 
MD 20771, United States 
(3) Research Institute for Sustainable Humanosphere, Kyoto University Uji, 
Kyoto 611-0011, Japan 
(4) University of Arizona, Lunar & Planetary Laboratory 1040 East Fourth St., 
Room 901, Tucson, AZ 85721, United States
(5) Department of Environmental, Earth, and Atmospheric Science, University of 
Massachusetts at Lowell 600 Suffold Street, Lowell, MA 01854, United States


The non-thermal continuum radiation is an electromagnetic emission
associated with the plasmapause and is an important feature of the coupled
inner magnetosphere. It is now believe that there are three main types of
non-thermal continuum radiation that are distinguished by their frequency
range and source location. The normal continuum radiation (also referred to
as the trapped and escaping continuum) is typically in the 5 to 100 kHz
frequency range. The continuum enhancement is observed from 10-100 kHz
frequency range coming from night-side source regions. Kilometric continuum
is observed to be generated at the plasmapause, in the magnetic equator,
deep in notch structures of the plasmasphere over a frequency range from 100
to 800 kHz. New observations of the normal non-thermal continuum from the
IMAGE/RPI instrument show a distinct "Christmas-tree" pattern in the
frequency-time spectrogram that extend from 10's of Hz into the kilometric
continuum frequency range (300 kHz). These observations show source region
at nearly all local times. New observations of the continuum enhancement
show that the emission is associated with night-side electron injections and
results in a very broad emission cone extending in frequency up to 300 kHz.
These new observations of NTC will be put in the context of their role in
the coupling of the hot and cold plasma populations at the plasmapause as an
inner magnetospheric response to geomagnetic storms.

_______________
Presentation, Fall A.G.U. Meeting, San Francisco, CA, 13-17 December 2004