To intercompare various techniques used in reconstructing tomographic
images, and to benchmark those results with direct observations obtain
ed by the incoherent scatter technique, an experimental campaign and s
ubsequent analysis program-the Russian-American Tomography Experiment
(RATE)-were implemented in late 1993. Russian experiment teams from th
e Polar Geophysical Institute in Murmansk and Moscow State University
joined with American investigators from the Phillips Laboratory and th
e Massachusetts Institute of Technology, and an array of four receivin
g stations was set up in the northeastern United States and in eastern
Canada to obtain data for the tomographic reconstructions. Phase-diff
erence and total-phase tomographic reconstruction techniques have been
employed and are intercompared. The spatial/altitude distribution of
ionospheric electron content was observed by the MIT Millstone Hill in
coherent scatter radar that scanned the ionosphere in a plane parallel
to the satellite overflights. We present preliminary reconstructions
of the ionospheric structure observed during a severe midlatitude iono
spheric storm that took place during the campaign. The drastic large-s
cale changes in the ionospheric structure that accompanied the Novembe
r 1993 storm were well observed by the two diagnostic techniques. (C)
1994 John Wiley and Sons, Inc.