# What is the mean ionospheric height?

I am reading some articles about the ionosphere and I am a little bit confused about the terms mean ionospheric height and effective height of the ionosphere. Are these the same thing?

Each type was analysed separately by calculating the yearly mean values of effective heights h’Es. It was found that the effective heights of the sporadic EsC, EsL and EsF vary within 105 - 132 km region with a typical period of a ...

...During 1967-1969 the average height for this sporadic layer type decreased relative to the mean level by about 20 km; for a long time afterwards (about 17 years) these values remained low, and it was not until 1985-1987 that they returned to the long-term mean level.

... The TEC must be found at the geographic point where the ray path intersects the mean ionospheric height, rather than at the user location. This point is taken here at a mean height of 350 kilometers. ...

I know that the mean height is used when one would like to express at which height a signal would pierce the ionosphere if we would approximate the ionosphere with one thin layer. And I also know that this is not the height of the electron density maximum.

The question is then, how is it (how are they) calculated?

• The respective heights are determined by the plasma frequency at that height, $\omega_{pe}$. Oscillations that satisfy $\omega < \omega_{pe}$ cannot propagate through the region where that condition is satisfied. May 23 '16 at 21:42
• May 13 '19 at 13:59