Ionospheric temporal and spatial variations during the 18 August 2003 storm over China
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 2007
Received: 1 September 2006
Accepted: 18 December 2006
Published: 7 May 2007
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.