ionogram

An ionogram is a display of the data produced by an ionosonde.

Here each ionogram has been plotted as a single time point to produce a plot of frequency against time.

Figure 3 shows a typical vertical ionogram.

The ionogram display shows the effective altitude of the ionospheric layer as a function of frequency.

Ionospheric Station of Gibilmanna "Latest Ionogram".

The result is displayed in the form of an ionogram, a graph of reflection height (actually time between transmission and reception of pulse) versus carrier frequency.

Jones, Oblique ionogram features associated with off-great-circle HF propagation at high latitudes, IEE Proc.

Oblique sounders use a transmitter at one end of a given propagation path, and a synchronized receiver, usually with an oscilloscope-type display (ionogram), at the other end.

Figure 27. A typical oblique ionogram for propagation from Svalbard in Norway to Chilton in the UK (click to enlarge).

Hence the maximum frequency or critical frequency of the vertical ionogram, fc, does not relate to the maximum frequency on the oblique ionogram.

The green trace, or ordinary ray, in the ionogram is the returned echoes from the component of the transmitted radio signal that is parallel with the direction of the Earth's magnetic field.

It highlights the extreme difficulty in ionogram profile inversion mentioned Section 1 (Vertical Ionogram Profile Inversion).

An ionogram movie from a much longer path of 3000 km (Svalbard, Norway to Chilton, in the UK) shows how the variability of propagation conditions is worse for people trying to communicate over longer paths.

In the International Union of Radio Science (URSI) he served with William Roy Piggott as co-author of the booklet on ionogram reduction and was vice-chairman and chairman of the ionospheric committee 1966-72.

Figure 37 shows a POLAN (see Vertical Ionogram Profile Inversion) electron density profile obtained form the Dynasonde (Wright 1998) digital vertical ionosonde based at the EISCAT facility in Tromsø.

The process of converting a vertical ionogram into a true-height electron density profile N(h) using a program called POLAN was discussed in Section 1 (Vertical Ionogram Profile Inversion).

Reduction rules are given in: "URSI Handbook of Ionogram Interpretation and Reduction", edited by William Roy Piggott and Karl Rawer, Elsevier Amsterdam, 1961 (translations into Chinese, French, Japanese and Russian are available).

Figure 25. A comparison between a measured vertical incidence ionogram recorded at Chilton and the MQP ray trace reconstruction of the vertical ionogram based upon a POLAN profile created from the original measurement (click to enlarge).