Polar radio disturbances during magnetic bays

Comparison of ionospheric and magnetic records at College Observatory, College, Alaska, shows very definite ionospheric effects during magnetic bays. High absorption producing partial to complete radio blackouts was coincident with each of 69 significant magnetic bays which were examined for the period January to September, 1942. The radio absorption is limited to duration of the magnetic bay, thereby establishing a direct relationship which is unusual in magnetic‐ionospheric investigations. Strong absorption of radio waves associated with complete disappearance of all signals is often encountered in the polar regions. This condition is known to become more pronounced during periods of magnetic and ionospheric disturbance. Continuous operation of the Observatory at College, Alaska, near the zone of maximum auroral and magnetic activity, has revealed important information concerning ionospheric characteristics and radio wave‐propagation in polar regions. College Observatory was established in 1941 by the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, in cooperation with the University of Alaska. It was operated by the Carnegie Institution of Washington until 1946 with support of the National Defense Research Committee, Navy Department, and the Wave Propagation Committee of the Joint Communications Board. Since 1946 operation was continued by the University of Alaska under contract with the Central Radio Propagation Laboratory of the National Bureau of Standards. The general program includes continuous ionospheric recordings over a wide range of frequencies, signal‐intensity recordings on high‐frequency broadcasting stations, magnetic observations, auroral studies, and special direction‐finder operations.