Abstract: Selected original analog telemetry tapes from three of the topside-sounder satellites of the International Satellites for Ionospheric Studies (ISIS) program, namely Alouette 2, ISIS I, and ISIS II, were used in an earlier project to produce more than million digital topside ionograms; the resulting digital topside ionograms from ISIS II were used to produce morethan 86,000 globally-distributed vertical topside ionospheric electron density profiles Ne(h)that cover a time span of more than a so…