Time history of high-latitude electron number density and radiowave absorption profiles during the solar cosmic-ray event of November 10, 1961

The weak solar cosmic-ray event of November 10, 1961, was responsible for relatively low values of 30-Mc/s cosmic noise absorption at Fort Churchill and Cape Jones, Canada, and pronounced VLF propagation effects on the path from Rugby, England, to College, Alaska. Utilizing solar proton energy spectrums measured by means of the Explorer 12 satellite, it was possible to calculate the electron production rate profiles at the magnetic dip pole for the 50-hour period following the onset of the PCA event; these were used to compute equilibrium electron number-density profiles, assuming currently accepted values for the rate coefficients. A considerable enhancement of the electron number densities was found in the D region and at lower altitudes. Computed values of the 30-Mc/s radiowave absorption are compared with cosmic noise absorption measured by means of 30-Mc/s riometers at Fort Churchill and Cape Jones, Canada. There is reasonable agreement except for times during the main phase of the PCA event.