Incorporation of topside half peak density anchor point in IRI Original Research Article

The F2 layer peak density (NmF2) and height (hmF2) are used by the International Reference Ionosphere as anchor point fitted by the electron density profile. The shape of the bottomside Ne(h) distribution is formulated with the help of profile sub-peak semithickness taken as a distance between the peak height and the bottom half-peak density height h05bot. In a similar manner relevant procedure allowing to fit IRI topside electron density profile to additional anchor point — the half-peak density height h05top at electron density equal to 0.5 × NmF2 above the F2 peak is included in the IRI ionosphere-plasmasphere model. Two types of :input are used with IRI code for 14 intense magnetic storms during 1999–2003: ionosonde derived data (ƒoF2, hmF2 and hO5bot) and Global Positioning System (GPS)-based total electron content (TEC) observation. It is shown that topside half-peak height h05top and topside scale height can be inferred from the GPS-TEC measurements with an iteration procedure applied to IRI profiling algorithm. The proposed technique is validated with incoherent scatter ionospheric electron content, ITEC, provided by EISCAT electron density profiles. Good correlation is obtained between the height h05top and the equivalent slab thickness τ, representing ratio of TEC to NmF2. This approach allowed us to reveal a highly variable topside scale height for intense space weather storms at mid latitudes with peaks up to 800 km during the peaks of magnetic activity.