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spectrum corresponding to the backscatterfrom Farley-Buneman waves. Note that themain transmitting antenna beam for the radarwas directed toward Arctic Village, explainingwhy the image peripheries are mainlydark. Backscatter is received from those regionswhere the threshold condition for instabilityis satisfied. For the most part, the individualDoppler spectra contain combinationsof type 1 and type 2 echoes. Abrupt changesin image brightness, hue and saturation fromrange to range and azimuth to azimuth signalchanges in the convection electric fieldmagnitude and/or direction. The scale sizesof these variations are kilometric and are invisibleto other ground-based instruments.Animated sequences of auroral electrojetimages spaced in time by a few seconds conveya sense of the rapid evolution of the radaraurora and the underlying convection patternat intermediate and small scales. Fine timeresolution as well as spatial resolution is evidentlynecessary to compute accurate convectionpatterns and derived quantities like Jouleheating rates if the results are to remain uncontaminatedby coarse averaging.ReferencesAbles, J. G., Maximum entropy spectral analysis,Astron. Astrophys. Suppl. Ser., 15,383, 1974.Chau, J. L., D. Scipion, and L. A. Flores,Interferometric observations of E regionfield-aligned irregularities with the PiuraVHF radar, paper presented at the IUGG2003 meeting, June 30 – July 11, Sapporo,Japan, 2003.Daniell, G. J., Of maps and monkeys. InBuck, B., and V. A. Macaulay, editors,Maximum Entropy in Action, chapter 1,pages 1–18. Clarendon, Oxford, 1991.Farley, D. T., H. M. Ierkic, and B. G. Fejer,Radar interferometry: A new techniquefor studying plasma turbulence in the ionosphere,J. Geophys. Res., 86, 1467, 1981.Hysell, D. L., A review and synthesis ofplasma irregularities in equatorial spreadF, J. Atmos. Sol. Terr. Phys., 62, 1037,2000.Hysell, D. L., and J. L. Chau, Imaging radarobservations and nonlocal theory of largescalewaves in the equatorial electrojet,Ann. Geophys., 20, 1167, 2002.Hysell, D. L., and R. F. Woodman, Imagingcoherent backscatter radar observations oftopside equatorial spread F, Radio Sci., 32,2309, 1997.Hysell, D. L., M. Yamamoto, and S. Fukao,Imaging radar observations and theory oftype I and type II quasiperiodic echoes, J.Geophys. Res., 107, 1360, 2002.Jaynes, E. T., On the rationale of maximumentropymethods, Proc. IEEE, 70, 939,1982.Jaynes, E. T., Where do we go from here? InSmith, C. R., and W. T. Grandy, Jr., editors,Maximum-Entropy and Bayesian Methodsin Inverse Problems, pp. 21-58. D. Reidel,Dordrecht, 1985.Kudeki, E., and F. Sürücü, Radar interferometricimaging of field-aligned plasmairregularities in the equatorial electrojet,Geophys. Res. Lett., 18, 41, 1991.Shannon, C. E., and W. Weaver, The MathematicalTheory of Communication, Univ.of Ill. Press, Urbana, 1949.Skilling, J., Fundamentals of MaxEnt in dataanalysis. In Buck, B., and V. A. Macaulay,editors, Maximum Entropy in Action, chapter2, pages 19–40. Clarendon, Oxford,1991.Thompson, A. R., Interferometry and Synthesisin Radio Astronomy, John Wiley, NewYork, 1986.101