On 20 September 1999 UT (21 September in local time, LT) a large earthquake Mw=7.7 struck central Taiwan near the small town of Chi-Chi. The greatest plasma frequency in the ionosphere, foF2, observed by the ChungLi ionosonde (25.0N, 121.2E) reveals three clear precursors at 1, 3, and 4 days prior to the earthquake. This paper examines the ionospheric total electron content (TEC) observed by a ...

[1] Using Global Positioning System (GPS) data from sites near the 16 Oct. 1999 Hector Mine, California earthquake, Pulinets et al. (2007) identified anomalous changes in the ionospheric total electron content (TEC) starting one week prior to the earthquake. Pulinets (2007) suggested that precursory phenomena of this type could be useful for predicting earthquakes. On the other hand, and in a s...

This paper studies the ionospheric response to a major geomagnetic storm of October 18-19, 1995, using the thermosphere-ionosphere electrodynamics general circulation model (TIEGCM) simulations and the global ionospheric maps (GIM) of total electron content (TEC) observations from the Global Positioning System (GPS) worldwide network. The TIE-GCM results, which utilize the realistic time-depend...

The ionosphere affects the electromagnetic waves that pass through it by inducing an additional transmission time delay. The ionosphere influence has now become the largest error source in GPS positioning and navigation after the turn-off of the Selective Availability (SA). In this paper, methods of 2D gridbased and 3D tomography-based ionospheric modeling are developed based on regional GPS re...

Original scientific paper For all scientific studies, for processing analytical data the subject of outliers is of critical importance. The accuracy of Total Electron Content (TEC) models obtained from ground based Global Positioning Systems (GPS) data is strongly affected by some factors such as satellite geometry, cut-off angle, ionospheric shell height, quantity of GPS data etc. Probable out...

Abstract We carried out a statistical analysis of the propagation characteristics Es and Medium-Scale Traveling Ionospheric Disturbances (MSTIDs) by combining data HF Doppler (HFD) sounder Total Electron Content (TEC) obtained from GPS receivers GEONET (GPS-TEC) for 4 years 2014 to 2017. made use reflection HFD in Sugito, Saitama (36.0°N, 139.7°E), Fujisawa, Kanagawa (35.3°N, 139.5°E), Sugadair...

In this work the response of the ionosphere due to the severe magnetic storm of 7–10 November 2004 is investigated by analyzing GPS Total Electron Content (TEC) maps constructed for the South America sector. In order to verify the disturbed zonal electric fields in South America during the superstorm, ionospheric vertical drift data obtained from modeling results are used in the analysis. The v...