AAS 200th meeting, Albuquerque, NM, June 2002
Session 49. New Frontiers in Solar and Space Weather Radiophysics
SPD Topical Session Oral, Tuesday, June 4, 2002, 2:00-3:30pm, 3:45-5:30pm, Ballroom B

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[49.09] Prospects for a Solar Radar at Arecibo

W. A. Coles (Univ. of Calif. at San Diego)

The idea of probing the solar corona with radar is so obvious that the Sun was the second target (after the moon) attempted in the development of radar astronomy. Echoes were detected by the Stanford group in 1960, and extensive observations were made between 1961 and 1969 by the MIT group. The results were unexpected in every respect: the echo power was weaker than expected and highly variable; the Doppler shift and broadening were greater than expected and were also highly variable; and the delay was more variable than expected. The results were never explained, even qualitatively. It became impossible to repeat them because radar astronomy evolved towards use of higher frequencies which penetrate the corona and are absorbed in the photosphere. In retrospect the early work was "ahead of its time" as solar echoes will be strongly affected by coronal holes and coronal mass ejections, neither of which were known in 1969. The purpose of this paper is to point out an opportunity to create a solar radar at the Arecibo Observatory, in conjunction with a proposed ionospheric heater. The two applications will not interfere and cost-sharing makes both feasible. The new radar will have five major improvements over the original: (1) complementary solar observations; (2) modern signal processing; (3) dual polarization; (4) frequency agility; (5) tracking. These will provide many benefits, but the "killer-app" may be the ability to directly measure the coronal magnetic field. The frequency will be tunable between 18 MHz and 26 MHz, which correspond to reflection heights of 1.85 Rs and 1.65 Rs respectively. Here we will summarize the early results; outline the design of the proposed radar; and present some simulations of its performance.

If you would like more information about this abstract, please follow the link to http://www-ece.ucsd.edu/~coles/solar-radar/. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.