As it was mentioned in many publications, the Bent model for the topside ionosphere used in IRI is not adequate, especially for the periods of high solar activity.
The observed GPS-TEC has been compared with the IRI-2007 moderivedived TEC considering three different options IRI-20011, IRI-2001 corrected and Ne-Quick) available in the model for the topside electron density.
In an earlier paper Třísková et al. (2002) have presented a new global empirical model for the topside ion composition based on data from the Intercosmos 24 satellite (ACTIVE mission).
Piles are usually left in place for naturally degrading, therefore, different 4D/5D BIM model relationships for topsides (T i ), jacket (J j ), and substructure (S k ) of the fixed platform were created in this study.
A new model of topside ionosphere scale height is developed, based on the vertical electron density (Ne) profiles obtained from topside ionosondes.
In the present study, the algorithm applied in the IRI-Plas model for obtaining the topside scale height, Hsc, when the F2-peak parameters are available from observation (Gulyaeva, 2011) is updated using the input of GPS-derived TEC to obtain both the instantaneous peak electron density and the topside scale height by fitting the model result TECiri to TECgps.
Moreover, the overall monthly variation of the VTEC shows that it is generally better to use the model with the NeQuick option for topside electron density.
In relation to the development of an operational ionospheric monitoring and imaging system, the most frequently used analytical ionospheric profilers (Chapman, Epstein, Exponential) were investigated in terms of suitability for topside ionosphere modelling.
Figure 2 presents the contour diagram showing diurnal variation of monthly mean GPS-TEC and IRI 2012 model TEC with three different options for topside N e, IRI-Neq, IRI 2001, and IRI-01-Corr, over Singapore for the year 2011.
Figure 1 shows the contour diagram showing diurnal variation of monthly mean GPS-TEC and IRI 2012 model TEC with three different options for topside electron density (N e ), IRI-Neq, IRI 2001, and IRI-01-Corr over Singapore for the year 2010.
