This three year continuation of a program to monitor ELF/VLF radio noise (frequencies in the range 5 Hz to 32 kHz) at Arrival Heights, Antarctica, will extend the observational record to more than twenty-five years, and will allow more precise estimates of and limits on noise statistics. The radiometer was first installed at its present location during the austral summer of 1984-5 and has provided a record of ELF/VLF noise in the Antarctic that is unprecedented in its continuity and duration. In parallel with this system, identical ones are currently in operation at Sondrestromfjord, Greenland, and on the Stanford University campus. These additional systems provide comparison data for the arctic and for mid-latitudes.
Since the predominant sources of ELF/VLF radio noise are thunderstorms occurring in the tropical regions, these three systems provide complementary views of the thunderstorm activity occurring in the tropics. The long-term statistics can then provide independent information about global change. The low background in the Arrival Heights record further allows the determination of Schumann resonances, quasi-standing waves that exist in the Earth's electromagnetic cavity (the space between the surface of the Earth and the Ionosphere). Temporal changes in these resonant frequencies can be related to variations in the characteristics of the ionosphere. Because of the great difficulty of making long-term observations, particularly at remote locations, the Arrival Heights measurements are increasing in scientific value as the radiometer continues in operation.
