Abstract
Abstract The effects of the 18 August 2003 geomagnetic storm on the ionosphere over China have been first studied by combining dual-frequency Global Positioning System (GPS) observation data from the Crustal Movement Observation Network of China (CMONOC) using the computerized ionospheric tomography (CIT) technique. The temporal and spatial variations of the ionosphere are analyzed using a time series of ionospheric electron density (IED) maps, and the ionospheric storm evolution process is revealed. The tomographic results show that the main ionospheric effects of this storm over China are: (1) that positive storm phase effects usually happen in the low-latitude ionosphere, (2) that negative storm phase effects occur in the mid-latitude ionosphere, and (3) that the equatorial anomaly structure can also be found. In contrast to the quiet period of the ionosphere on 17 August 2003, the equatorial anomaly crest moved to the north in the main phase of the storm and then moved back to the original location in the recovery phase on 19 August 2003. We compared the peak density NmF2 and the peak height hmF2 obtained from the ionosonde observations at Wuhan station and those inverted by the CIT technique to confirm the reliability of the GPS-based tomographic technique. The tomographic results revealed that the GPS-based CIT technique can be used to monitor large-scale ionospheric disturbances during geomagnetic storms.
Highlights
Substantial signal delays are expected when satellite radio signals traverse through the ionosphere due to the dispersive nature of the ionosphere
One can see that the ionospheric equatorial anomaly still existed and that the equatorial anomaly crest moved to 27◦N; the crest of the anomaly structure moved back to the original locations at 13:00 UT on 19 August 2003 (Fig. 1(c))
In this work, a Global Positioning System (GPS)-based computerized ionospheric tomography (CIT) technique is applied to study the ionospheric response to the magnetic storm on that occurred on 18 August 2003
Summary
Substantial signal delays are expected when satellite radio signals traverse through the ionosphere due to the dispersive nature of the ionosphere. Since geomagnetic storms have global effects, it is necessary to apply global observations to study the large-scale disturbed performance of the ionospheric structure during geomagnetic storms.
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