Residual Analysis of Global Ionospheric Maps Using Modip Latitude

In this paper we propose the use of the modip (instead of the geomagnetic) latitude for both: i) to compute Global Ionospheric Maps (GIMs) of vertical Total Electron Content (vTEC) based on GNSS observations; and ii) to validate those maps by means of comparisons to other vTEC sources of information, as TOPEX/Poseidon. We show several examples that indicate that mis-model problems of GIMs are both: i) better identified if the differences between the vTEC coming from different sources of information (GPS and TOPEX in this case) are analyzed in terms of the modip latitude; and ii) reduced by modeling the vTEC variability in terms of the modip latitude.