At a recent meeting of the incoherent scatter radar user community an experiment was planned to observe the ionospheric and thermospheric response to the May 30, 1984, annular solar eclipse with the meridional radar chain whose elements span the eclipse path. Investigators from the National Center for Atmospheric Research (NCAR), the Air Force Geophysics Laboratory, SRI International, Arecibo Observatory, and the Massachusetts Institute of Technology (MIT) Haystack Observatory were involved in this experiment. The operation of the incoherent scatter radars is sponsored by the National Science Foundation Atmospheric Sciences Division.
Three radars participated in the observations of the eclipse effects: Arecibo (18°N), Millstone Hill (43°N), and Sondrestrom (67°N). The Millstone Hill radar was within 3° latitude of the path of the eclipse and experienced a maximum solar obscuration of 92% at 1705 UT. The eclipse duration was approximately 3 hours. Measurements at Millstone Hill included electron density, plasma temperatures, and ion drifts overhead using the 67-m zenith antenna and to the south and southwest at low elevations (10–15°) using the 46-m steerable antenna to map drift velocity vectors and extend the observations towards the Arecibo station. Millstone Hill began gathering observations at 1200 UT and continued through the eclipse to 2200 UT. The automated data processing and graphics capabilities at Millstone Hill were utilized to obtain initial results of the eclipse observations within 12 hours of the completion of the experiment, and the data were placed in the remotely accessible user data base on the Millstone computer. These data are available to the research community on request.