Auroral-zone observations of infrasonic pressure waves related to ionospheric disturbances and geomagnetic activity

Observations at Fort Yukon, Alaska, in August 1962 showed that most of the 10- to 110-sec-period infrasonic pressure waves during that period originated in auroral disturbances. Associated magnetic and cosmic noise absorption effects, together with determinations of the arrival direction of the pressure fluctuations, indicated an ionospheric source. We also studied a unique event, not of the auroral type, which appeared to give evidence that a large, primarily tropospheric pressure front could produce a disturbance in the ionosphere. Mechanisms for the two types of observations can be found in well-accepted, auroral-zone ionospheric processes.