Ionospheric electron temperature at solar maximum

Langmuir probe measurements made at solar maximum from the Dynamics Explorer-2 satellite in 1981 and 1982 are employed to examine the latitudinal variation of electron temperature, T_e, at altitudes between 300 and 400 km and its response to 27 day variations of solar EUV. Comparison of these data with T_e models based on the solar minimum measurements from Atmosphere Explorer-C suggest that the daytime T_e does not change very much during the solar cycle, except at low latitudes where an especially large 27 day variation occurs. The 27 day component decreases from about 7°/F10.7 unit at the equator to 3°/F10.7 unit at 851V 3 middle and higher latitudes. From these DE-2 measurements, and those from AE-C, we conclude that the daytime T_e near the F₂ peak is more responsive to short-term (daily) variations in F10.7 than to any longer term changes that may occur between solar minimum and solar maximum. To investigate this sensitivity of the dayside ionosphere to solar activity we employ the inverse relationship of T_e and N_e, that was found at solar minimum, to see if it can be used to order the T_e behaviour at solar maximum. We introduce a simple quadratic correction for the F10.7 influence on T_e based on the entire daytime AE-C and DE-2 data base between 300 and 400 km. Although this equation may be found useful, the systematic deviations of the DE-2 data suggest that the solar minimum model does not accurately describe the T_e-N_e relationships at solar maximum, at least above 300 km where the DE-2 measurements were made. Future work with this data base should attempt to see if such a relationship exists.