ByusingobservedCHAMPorbitephemeredesandMSISE-90dryairmodelandregardingtheearthasasphereandanellipsoidrespectively,phasedelaysaresimulatedandthesimulateddataareretrievedunderdifferentschemes.Thecomparisonbetweentheinvertedtemperatureprofilesandthemodeltemperatureprofilesshowsthatbyinvertingobserveddata,wewillgettemperatureresultswithlargeerrorsiftheeffectofEarth'soblatenessisomitted.Thecorrectionmethodisprovedtobeeffectivebecausethetemperatureerrorsdecreasedobviouslywiththismethod.