Publication Date:
2014-10-01
Description:
As described in a previous paper [ Tsai et al ., 2009], a three-dimensional ionospheric electron density ( N e ) model has been constructed from vertical N e profiles retrieved from the FS3/COSMIC GPS radio occultation (RO) measurements and worldwide ionosonde foF2 and foE data, and named the TaiWan Ionospheric Model (TWIM). The TWIM exhibits vertically fitted α-Chapman-type layers with distinct F2, F1, E, and D layers, and surface spherical harmonic approaches for the fitted layer parameters including peak density, peak density height and scale height. To improve the TWIM into a real-time model we have developed a time series autoregressive model to forecast short-term TWIM coefficients. The time series of TWIM coefficients are considered as realizations of stationary stochastic processes within a processing window of 30 days. These autocorrelation coefficients are used to derive the autoregressive parameters and then forecast the TWIM coefficients, based on the least squares method and Lagrange multiplier technique. The forecast root-mean-square relative TWIM coefficient errors are generally 〈30% for one day predictions. The forecast TWIM values of foE and foF2 values are also compared and evaluated using worldwide ionosonde data.
Print ISSN:
0048-6604
Electronic ISSN:
1944-799X
Topics:
Geosciences
,
Physics
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