GPS-based TEC derivation and its dependence on ionospheric height assumption

With GPS observation from a small scale network and the grid-based algorithm to derive TEC and instrumrntal bias, the effects of the thin shell ionospheric height assumption on GPS-based TEC is studied. While the trend of TEC variation with time retains, TEC tends to increase with the height. The times at which the TEC peaks or reaches the minimum do not change significantly with the height. The instrumental biases can vary with the height irregularly. The goodness of fit is different for different height. The fitting is generally good when the height is taken from 350 km to 700 km. There does not exist a best height assumption. It has large deviations for the height lower than 350 km. The goodness of fit worsens monotonously when the height decreases from 280 km to 250 km.