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First LOIS Workshop, June 17-19, 2001 Växjö University, Sweden |
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with LOFAR and LOIS
Brett Isham
brettisham@mac.com, www.eiscat.uit.no
EISCAT Scientific Association
Tromsø, Norway
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Abstract
A large new HF/VHF receiving array known as the Low Frequency Array
(LOFAR) has been proposed for radio astronomy and atmospheric science
observations. Assuming that LOFAR is to be located in and near the
Netherlands, the LOFAR Outrigger in Sweden (LOIS) project proposes
the construction in southern Sweden of additional LOFAR receiving
stations along with a powerful CW transmitter. Such a transmitter
would allow the LOFAR/LOIS system to be used for a number of
interesting space weather measurements beyond those possible using
passive receivers alone. Prominent among these is ground-based radar
observations of the solar corona, a technique known as solar radar.
Solar radar was shown to be a viable and interesting technique for
the study of the sun by James [Astrophys. J., 146, 356-366, 1966].
Solar radar frequencies lie in the 10 to 100 MHz range, and scatter
from the coronal plasma occurs at or near the corresponding plasma
resonance level, generally between one and five solar radii from the
center of the sun. Because of this, solar radar is an ideal
technique for the study of coronal structure and dynamics, including
wave activity, turbulence, and explosive events such as CMEs. What
is new today is the possibility of high resolution imaging radar
observations and the opportunity to participate in multi-instrument
solar observing campaigns in which the collective database provides
enhanced possibilities for understanding the observations. Past
observations and their theoretical interpretations will be reviewed,
and past and potential solar radar systems, in particular LOFAR/LOIS,
will be discussed.
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