Effects of geomagnetic storm on GPS ionospheric scintillations at Sanya

• Published in: Journal of atmospheric and solar-terrestrial physics Vol. 70; no. 7; pp. 1034 - 1045
• Main Authors: Li, Guozhu, Ning, Baiqi, Zhao, Biqiang, Liu, Libo, Liu, J.Y., Yumoto, K.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2008; Elsevier
• Subjects: Earth, ocean, space; Electric fields; Equatorial ionosphere; Exact sciences and technology; External geophysics; Ionospheric scintillations; Irregularities; Physics of the ionosphere; Physics of the magnetosphere; Ionospheric scintillations; Irregularities; Equatorial ionosphere; Electric fields; Vertical speed; Minimum solar activity; magnetic storms; scintillations; Global Positioning System; electrical field; Sunset; K index; Vertical drift; Ionospheric disturbance; Scintillation index; statistical analysis; Drift velocity; storms; Kp index
• ISSN: 1364-6826; 1879-1824
• DOI: 10.1016/j.jastp.2008.01.003

The effects of geomagnetic storm on GPS ionospheric scintillations are studied here using GPS scintillation data recorded at Sanya (18.3°N, 109.5°E; geomagnetic: 7.6°N, 180.8°E), the southmost station in the Chinese longitude region. GPS scintillation/TEC and DMSP data are utilized to show the development of irregularities during the period year 2005 (solar minimum). Statistical analysis of K planetary index (Kp) and amplitude scintillation index (S4) indicates that most storms of the year did not trigger the scintillation occurrence at Sanya. However, cases of scintillation occurring during moderate and strong storm (Dst<−100) periods show clearly that the development of irregularities producing scintillations can be triggered by geomagnetic storms during the low scintillation occurrence season. The effects (trigger or not trigger/inhibit) depend on the maximum dDst/dt determined local time sector, and can be explained by the response of the equatorial vertical drift velocities to magnetospheric and ionospheric disturbance electric fields. For station Sanya, the maximum dDst/dt determined local time is near the noon (or post-midnight) sector for most storms of the year 2005, which inhibited (or did not trigger) the post-sunset (or post-midnight) scintillation occurrence and then led to the phenomena that the statistical results presented.