Regional ionospheric trend statistics: IONOLAB-PDF

Abstract

The ionosphere plays an important role for HF bands, space-based positioning systems, satellite communication, and propagation. The variability of the ionosphere has a complex spatiotemporal characteristic, which depends on statistical parameters. Total electron content (TEC) is one of the major observables for investigating and determining this variability. In this study, spatiotemporal within-the-hour statistical characteristics of TEC are determined for Turkey, which is located in midlatitude, using the TEC estimates from the Turkish National Permanent GPS Network- Active between the years 2009 and 2012. The TEC values have strong hourly, seasonal, and positional dependence on east-west direction, and the trend shifts according to sunrise and sunset hours. It is observed that TEC is distributed predominantly as lognormal and Weibull probability density functions (pdf). Within-the-hour pdf estimates are grouped into ionospheric seasons such as March equinox, summer, winter, and September equinox. In winter and summer seasons lognormal and during equinox seasons Weibull distributions are observed more frequently. For spatial analysis, all TEC values within the same hour and in the same region are combined in order to improve the reliability and accuracy of pdf estimates. Statistical characterization of TEC over Turkey will contribute to developing a regional and seasonal random field model, which will be used in HF channel characterization and space weather risk analysis.