Ionospheric Propagation Effects on GNSS Signals and New Correction Approaches - Global Navigation Satellite Systems: Signal,Theory and Applications - page 392

the dependency on B field, the second order term depends on the receiver's geographic /
geomagnetic position and direction of the signal reception. Such dependencies are given in
Fig. 4. The simulation has been made using a two dimensional ray tracing program (Hoque
& Jakowski, 2008) which includes International Geomagnetic Reference Field (IGRF)
(Mandea & Macmillan, 2000) model for magnetic field computation along ray paths. A
single layered Chapman profile (Eq. 40, see Rishbeth & Garriott, 1969) with a maximum
ionization of 4.96×10 12 m -3 at 350 km altitude and atmospheric scale height of 70 km has
been used, and the corresponding vertical TEC is found 143 TECU.

()

2
Igr

Fig. 3. Frequency dependence of the second order term d at different levels of ionospheric

ionization and elevation angles

Fig. 4. Azimuth dependency of the second order term at GPS L1 frequency for elevations 5°,
30° and 60° and VTEC = 143 TECU. The receiver position is considered at geographic 25° N,
10° E and at its geomagnetic conjugate position 3.4° S, 11° E. The symbols N, E, S and W
correspond to the geographic north, east, south and west directions, respectively