Solar cycle variations of mid-latitude electron density and temperature: Satellite measurements and model calculations

For Ne good agreement is found between the data and models in terms of variations pattern as well as absolute values. Whereas Ne always increases with solar activity, Te can increase, decrease, or stay constant depending on the specific altitude, local time and season. At 550 km the daytime Te increases with solar activity in summer, decreases in equinox and stays almost constant in winter. At this altitude range we find generally good agreement between the variations seen with the satellite data and those predicted by the FLIP and Millstone Hill models. At 850 km, however, significant discrepancies are noted. The satellite data, primarily DMSP in this altitude range, are consistently higher than the Millstone Hill model averages and include unrealistically high temperatures (4000-5000 K) at very low solar activities. The FLIP model also predicts much lower values at low solar activities but otherwise (for middle to high solar activities) agrees well with the satellite data. During nighttime the FLIP model underestimates Te at 850 and 2000 km altitude for the summer and equinox seasons. The current IRI Te model does not include variations with solar activity. The IRI values are generally in between the satellite and radar averages with a few exceptions.