Estimation of Probability Density Function for TUSAGA TEC

In this study, the statistical properties of the Ionosphere are investigated by using Total Electron Content (TEC) estimates obtained from TUSAGA GPS stations in Turkey. The hourly histograms of TEC are computed using the processed data from 14 GPS stations located mostly in western Anatolia. Optimum Probability Density Function (PDF) that fits the histograms is investigated in Maximum Likelihood sense. It is observed that for all the stations and all hours of the day, TEC is distributed as Lognormal. The parameters of the Lognormal distribution are also very similar to each other. Generally, the mean of the PDF increases when the sun is close to local zenith and it decreases right before the sun rise and sunset. It is observed that a representative TEC PDF that can be used in statistical modeling of ionosphere over Turkey using a GPS network that covers Turkey homogeneously.