IONEX

IONosphere-map EXchange (IONEX) Files

As they travel through the ionosphere, GNSS signals get distorted by the effect of the ionised plasma the ionosphere is composed of. Roughly speaking, navigation signals will get delayed and their direction will change as they pass through the ionosphere. The magnitude of the effect depends on the elevation of the satellite above the horizon and the position of the Sun in the sky. it should therefore come as no surprise that information on the ionosphere can also be gleamed from GNSS signals. 

Analysis of the GNSS signals as they arrive at a station on the ground can therefore give us very important information on the state of the ionosphere. Being essentially a plasma, the important parameter here is the density of electrons. IONEX files contain the so called TEC (Total Electron content). TEC is nothing but a measure of the number of free electrons in a column through the ionosphere with a cross-sectional area of 1 square meter. For reasons of convenience a density of 10¹⁶  is one unit of TEC.

IONEX files contain apart from TEC maps, RMS error maps for the TEC maps and also height maps.

The GSSC supports the current IONEX Standard IONEX v1.0 as ‘Resource type’ ‘Ionospheric products’.