Trend Characterization For Midlatitude Ionosphere

A locally planar Total Electron Content (TEC) trend model for the midlatitude region encompassing a major part of Turkey and some Balkan countries is investigated by estimating its coefficients for the year 2011. The TEC values are obtained from Global Ionospheric Maps (GIM). The model coefficients are estimated using Least Squares (LS) and Recursive Least Squares (RLS) methods. The estimated model coefficients are used to generate model maps and the difference between these and actual GIM are obtained in squared L-2 sense as a performance indicator. The planar trend model provides a successful representation of TEC for the midlatitude region taken into consideration. While the coefficients estimated with LS better represent the high variability of TEC, those estimated with RLS present a good fit for the underlying TEC trend throughout the year.