A study in March and April, 1960, showed variations in the auroral zone ionospheric absorption of cosmic noise to be closely related to magnetic field micropulsations and short period coruscations of λ 3914. At times of polar‐cap type absorption, magnetic micropulsation amplitudes were diminished. Auroral ionization in theEregion, estimated from a particular luminosity‐height profile, accounted for 50 per cent, at least, of the cosmic noise absorp