Rocket Measurement of a Daytime Electron Density Profile up to 620 Kilometers

On April 27, 1961 at 1502 EST a four-stage research rocket was fired from Wallops Island, Virginia, to measure the ionospheric electron density distribution by means of Seddon's CW propagation technique. This experimental technique is based upon the dispersive Doppler effect measured at two harmonically related frequencies, in this case f = 12.267 Mc and 6f = 73.6 Mc. The electron density profile measured above the peak of the F2 region is representative of a diffusive-equilibrium distribution in an isothermal ionosphere having a temperature of 1640 deg +/- 90 deg K. This result, when compared with satellite and other data, indicates that the upper ionosphere is in thermodynamic equilibrium.