Performance of GPS slant total electron content and IRI-Plas-STEC for days with ionospheric disturbance

Total Electron Content(TEC) is an important observable parameter of the ionosphere which forms the main source of error for space based navigation and positioning systems.Since the deployment of Global Navigation Satellite Systems(GNSS),cost-effective estimation of TEC between the earth based receiver and Global Positioning System(GPS) satellites became the major means of investigation of local and regional disturbance for earthquake precursor and augmentation system studies.International Reference Ionosphere(IRI) extended to plasmasphere(IRI-Plas) is the most developed ionospheric and plasmaspheric climatic model that provides hourly,monthly median of electron density distribution globally.Recently,IONOLAB group(www.ionolab.org) has presented a new online space weather service that can compute slant TEC(STEC) on a desired ray path for a given date and time using IRI-Plas model(IRI-Plas-STEC).In this study,the performance of the model based STEC is compared with GPS-STEC computed according to the estimation method developed by the IONOLAB group and includes the receiver bias as IONOLAB-BIAS(IONOLAB-STEC).Using Symmetric Kullback-Leibler Distance(SKLD),Cross Correlation(CC) coefficient and the metric norm(L2N) to compare IRI-Plas-STEC and IONOLAB-STEC for the month of October 2011 over the Turkish National Permanent GPS Network(TNPGNActive),it has been observed that SKLD provides a good indicator of disturbance for both earthquakes and geomagnetic storms.