Regularized estimation of TEC from GPS data for certain midlatitude stations and comparison with the IRI model

Abstract

Regularized estimation of Total Electron Content (Reg-Est) is a novel technique which can combine signals from all the satellites for a given instant and given station and estimate the vertical TEC (VTEC) values for any desired period without missing any important features in the temporal or spatial domain. The preprocessed signals from all the satellites that are received for a certain time period are weighted according to their positions with respect to the local zenith. A two step regularization algorithm combines these signals and provides smooth VTEC estimates for the desired time period which can be as short as half an hour or as long as 24 h. The estimation algorithm is tried on VTEC values obtained from six midlatitude stations for the quiet and disturbed days of October, 2003. Within this period, the same estimation parameter set is used for all stations and time periods. When the regularized estimation results are compared with those from IRI-2001, JPL, CODE, UPC and ESA, best accordance is observed with JPL, UPC and CODE estimates. IRI computations usually provide a better fit for the night values. It is observed that the results from the regularized estimation algorithm are highly accurate in detecting disturbances and irregularities for various time scales and stations.

Inter-hemispheric imaging of the ionosphere with the upgraded IRI-Plas model during the space weather storms

“…Also, the input parameters of the IRI-Plas code ( f o F 2 , h m F 2 , TEC gps ) are not measured directly neither by the ionosonde nor the GPS receiver. These parameters are derived quantities that include modeling, computational and measurement errors due to a sophisticated pre-processing and signal manipulation (Piggot and Rawer, 1972;Arikan et al, 2002Arikan et al, , 2007Reinisch et al, 2005;Smith et al, 2008;Anghel et al, 2009). Therefore, this inherited controversy of input parameters may affect IRI-Plas results and yield greater RMS errors with an instantaneous input than with the more-smoothed monthly median values.…”

Probability density function estimation for characterizing hourly variability of ionospheric total electron content

“…The raw data for the GPS stations are obtained from the Web site of ftp://cddisa.gsfc.nasa.gov/gps/products/ionex/. The geographic and geomagnetic coordinates and station ID's of the selected 18 GPS stations are provided in Table 1 [13] The raw GPS data recordings for each station is processed with Reg-Est method and TEC estimates are obtained using www.ionolab.org as IONOLAB-TEC [Arikan et al, 2003;Arikan et al, 2004;Arikan et al, 2007;Nayir et al, 2007]. For each GPS station in Table 1, and lama, both midlatitude stations, are presented, respectively.…”

Regional TEC dynamic modeling based on Slepian functions

“…The necessary formula can be extracted from Sharifi and Farzaneh (2013). Once the VTEC values were computed for each satellite, they were combined in the least-squares sense as discussed in detail by Arikan et al (2007). These values were then used for the near-real time modeling.…”