URSI National Committee Report: Commission 3. Ionospheric Radio Propagation. Review of USA Activity in the Fields of Interest of URSI Commission 3 During the Triennium 1957 Through 1959

Abstract

Because of the IGY, there has been an unprecedented emphasis on the geophysical aspects of the ionosphere. Rockets, satellites, moon echoes, VLF propagation in the "whistler" mode, and, most recently, in coherent scatter by the ionospheric electrons have enabled the observable ionosphere to be extended far beyond the former limit set by the maximum electron density at 300 to 500 kilometers. During the IGY there was a considerable shift in emphasis in ionospheric investigations toward the polar regions, both arctic and antarctic. In the antarctic con ventional observing techniques were used; in the north, however, extensive programs of rocket and balloon observations were brought to bear on the special effects of the auroral zone. Ground-launched rockets were fired at Ft. Churchill, Canada, and balloon-launched r ockets (I'ockoons) were fired at various places. Balloon-borne r adiation counters were also flown at various places in and near the auroral zo ne. In the URSI, Commission 4 currently has the responsibility for ionospheric propagation at VLF a nd LF, for whistlers and whistler mode propagation, for hydromagnetic waves in t he ionosphere and the extra. low frequency oscillations (micropulsations) of the geomagnetic field which are thought to be associated with them, and for certain aspects of the exosphere. The reader is therefore referred to the report of USA Commission 4 for reviews of activity in these topics. This review is confined to work published between January 1957 and December 1959. A Iso rather than cover the same ground in detHi l, reference is m a de to reviews of Upper Atmosphere S tudies (under Meteorology and At mospheric Physics), and work in Geomagnetism and Geoelectricity, Solar-Terrestrial Relationships, Ionosphere, Aurora, Airglow, Chemistry o f t he Outer Atmosphere, and Radiation }lelts (under Geomagnetism and Aeronomy), in the Triennial Report of the American Geophysic!ll Union to the UGGI (Internationa l Union of Geodesy and Geophysics) [A GU, 19601. Another important r eview Praper [JTAC, 19601 on radio transmission by ionospheric scatter was prcpared b y the J oint Technic!ll Advisory Committee of the Institute of R adio Engineers and of the R a dio fi od Television Manufacturers Association_