Data acquired with the Geophysics Laboratory's high-latitude meteor scatter test-bed between Sondrestrom Air Base (AB) and Thule AB, Greenland, during the solar disturbances of March and August 1989 are presented. These disturbances provided a unique opportunity to observe a number of naturally occurring disturbance effects on meteor scatter links operated in the frequency range (35 to 147 MHz) covered by the test-bed. The disturbances range from signal absorption to system noise variations. The properties of ionospheric absorption in general are discussed and illustrated with computations using electron density profiles from the September 1978 solar proton event (SPE). It has been found that accurate measurements of high levels of ionospheric absorption with riometers pose special problems. These problems are identified and discussed. The data acquired during the March and August 1989 solar disturbances are then related to the zenith absorption measured at Thule, and the influence of absorption as well as system noise variations are discussed. The two events presented are very different. The August event was dominated by ionospheric absorption which affected meteor arrival rates and duty cycles primarily at the lower frequencies (35 and 45 MHz), although some effects could also be seen at the higher frequencies (65 to 147 MHz). The March event combined weak ionospheric absorption with large solar noise bursts. The effects of this event on the test-bed were dominated by increased solar noise at all frequencies. The relative influence of solar noise and ionospheric absorption during SPE events is discussed along with speculation as to the validity of frequency dependence conclusions based on testing of the JANET system.
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