POLAN

Titheridge's POLAN for estimating true ionosphere height from ionosonde measurements using polynomial analysis of sweep-frequency ionogram data.

POLAN is a classic Fortran program used to calculate real-height profiles from chirp ionosonde data from the ionosphere. The software performs polynomial analysis (POLynomial ANalysis) on sweep-frequency ionograms to determine the true height distribution of ionospheric electron density from virtual height measurements. Originally developed by J.E. Titheridge in the 1980s and documented in UAG-93 report, the code has been updated to compile on modern PCs. The program supports multiple analysis modes including overlapping polynomials and single-polynomial fits, handles both ordinary and extraordinary ray data, and includes sophisticated modeling of ionospheric valleys and Chapman layer peaks.