Comparison of the correlation of incoherent scatter and ionosonde measurements of temperature with calcium plage and 2800-megahertz intensities

The variation in the diurnal thermospheric neutral temperatures has been studied. Minimum and maximum temperatures were calculated from 20 sets of diurnal incoherent scatter measurements taken at Arecibo, Puerto Rico, which corresponded to a range of 2800-MHz intensity of 120 to 167×10−22watt m−2 sec−1. Minimum temperatures were also derived from 850 reduced ionosonde records obtained from Ramey, Puerto Rico, for which the 2800-MHz intensity varied between 74 and 252×10−22 watt m−2 sec−1. Both sets of measurements were seasonally distributed. Various combinations of the monthly mean and daily values of the 2800-MHz and Ca II solar indices were fitted to the data. A formula incorporating the difference between the daily and monthly average Ca II index and the monthly average 2800-MHz index provided a better fit to all the data than did formulas incorporating only the Ca II index or the 2800-MHz index alone. The phase and amplitude of the semiannual component and the term dependenton Kp were found to remain almost the same for the maximum and minimum temperature. The term dependent on the 27-day component of the solar activity was found to be about 4 times as large for the diurnal maximum as for the minimum.