The Global Positioning System (GPS) radio occultation (RO) technique has been used to receive multi-channel GPS carrier phase signals from low Earth or biting (LEO) satellites and demon strate active limb sounding of the Earth¡¦s ionosphere. Apply ing Abel inversion through compen sated total electron content (TEC) values, the GPS RO observations can obtainion o spheric electron density (ne) profiles and then scale F2-layer characteristics including foF2 and hmF2, especially, hmF2 that can not be directly deduced from ionosonde observations. From the GPS/MET and FS3/COS MIC mis sions, we can col lect on average two hundred and eighteen hundred vertical neprofiles, respectively, within one day. The retrieved foF2 and hmF2 re sults have been used to produce numerical maps representing complex prop erties on a world-wide scale. This paperpresents aphysically appeal ing represen tation of foF2 and hmF2 medians based on GPS RO data. The derived numerical maps have also been examined by ground-based ionosonde data.