THERMOSPHERIC PROPERTIES AS DEDUCED FROM INCOHERENT-SCATTER MEASUREMENTS

This paper reviews the results obtained over the past decade using the incoherent scatter technique that have contributed to present understanding of the structure of the thermosphere. Principal among these has been the measurement of the exospheric temperature with considerable accuracy (± 10-20 K) and time resolution (10-30 min) at four widely differing latitudes over periods of several years. These measurements contributed significantly to the development of the best empirical model for the thermosphere presently available, namely the MSIS model. Very recent results suggest that the thermospheric temperature dependence on Kp is not properly represented in the MSIS model for Millstone and that larger amounts of heat are deposited in the summer auroral zone than the winter one. In addition, it has been found from data gathered in France that the inverse scale height parameter s is not constant as assumed in the model, but decreases as F ̄f10.7 or Kp increases. The technique also is being used to study the oscillation of the temperatures, density and winds near the lower boundary of the thermosphere introduced by upward propagating tides. Also, seasonal variations of the composition of the thermosphere have been detected and support the view that atomic oxygen is transported from the summer to winter hemisphere. © 1979.