This is a 2d visual map of the concentration of electrons in the ionosphere. “The plot illustrates the height integrated electron density (TECU, 1 TECU = 1.e16 electrons/square meter) also called Vertical Total Electron Content (VTEC), vs latitude (-90 to 90 deg) and longitude (0 – 360 deg) from the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics … CTIPE—reprise