On the Spaced Antenna and Imaging Doppler Interferometer Techniques>
B. G. W. Vandepeer and I. M. Reid
Abstract
The theory developed by Briggs, [Radio Science 1994] in a companion paper is
extended to explain the measurement of a wind velocity equivalent to the
spaced antenna apparent wind by IDI-like interferometric analyses.
The point is made that the presence of turbulence,
or random change in the diffraction pattern on the ground, is directly
responsible for the difference between the true and apparent velocities
in the spaced antenna analysis, and also for the over-estimation of the wind
velocity by the IDI technique.
An experiment is conducted to determine whether the ``effective'' scattering
points resolved by IDI-like analyses tend to lie upon the azimuth predicted
by theory. This is found to be the case, even for unsmoothed cross-spectra
for which the theory was not explicitly derived. An averaging mechanism
is proposed which may explain the extent to which the unsmoothed experimental
data conform to the behaviour predicted by theory.
Status
This paper has been submitted for publication in Radio Science.
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