In a square pyramid, the true height, slant height, and length of the edge of the base face are all related by the Pythagorean theorem: (edge ÷ 2 2 + (true height)2 = (slant height)2.
If you only know the length of the angled side but not the parallelogram's true height, draw a line through either side of the parallelogram, turning it into a perfect square/rectangle with a triangle on either end.
In addition, much of the mountain is invisible even underwater: its mass depresses the crust beneath it by another 8 km, in the shape of an inverse mountain, meaning the true height of Mauna Loa from the start of its eruptive history is about 17170 m.
However, this may lead to a loss of spatial resolution and true height can anyway only be deduced by extrapolation [4, 20].
The GIRO provides access to the Automatic Real-Time Ionogram Scaler with True height (ARTIST) software, an "autoscaler" of ionogram traces that uses the heritage of algorithm development going back to the 1980s (Reinisch and Huang, 1983; Galkin et al., 2008b).
In Figs. 3(a)–(f) the solid curves show the true height profiles of the normalized plasma frequency.
However, nonlinear gradients (e.g. troughs and ridges) can influence the inversion results in such a way that they differ strongly from true height profiles of electron density in the reconstruction plane.
Titheridge (1961, 1967a, b, 1969, 1975, 1988) proposed a model-fitting method, or polynomial analysis in which the curve of true height vs. plasma frequency, h fp), is represented as a single or overlapping polynomial(s).
On these stations the ARTIST (Automated Real Time Ionogram Scaler with True height) software for ionogram automatic scaling and real-time NHPC with true height inversion are used.
