Ionospheric climatology derived from gps occultation observations made by the ionospheric occultation experiment

Abstract

The ionospheric occulta- tion experiment (IOX) is a GPS occultation sensor with an iono- spheric mission focus. IOX mea- surements of GPS L1 and L2 carrier phase during Earth limb views of setting GPS satellites are used to- gether with the Abel transform to determine vertical profiles of elec- tron density from which F-region peak parameters are determined. Data from a four and a half month period beginning in November 2001 are statistically binned and com- pared with a climatological model. To account for potential errors in interpretation that could arise from violation of the Abel transform assertion of spherical symmetry, the data are compared to both the cli- matology and to statistics of simu- lated ionospheric inversions using the climatological model. General characteristics of the climatology are reproduced by the occultation data. However, several significant dis- crepancies between the model and the data are observed during this near-solar maximum time period. In particular, average mid-latitude daytime densities are shown to be higher than the climatological pre- diction and the height of F2 layer in the post-sunset equatorial region is underestimated by up to 150 km.