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Ann. Geophys., 24, 3329-3341, 2006
www.ann-geophys.net/24/3329/2006/
© European Geosciences Union 2006
Latitudinal and temporal variation of equatorial ionospheric irregularities determined from GPS scintillation observations
M. A. Cervera1 and R. M. Thomas2
1Intelligence, Surveillance and Reconnaissance Division, Defence Science and Technology Organisation, PO Box 1500, Edinburgh, S.A. 5111, Australia
2Box 154, Cockatoo Valley, S.A. 5351, Australia
Abstract. In this paper we investigate the spatial and temporal distribution of
ionospheric irregularities in the South-East Asian longitude sector by
analysing the scintillation of GPS signals received at ground based stations.
The data used for this work were collected during 1998 to 2002 with our regional
network of GPS based scintillation monitors (Thomas et al., 2001).
The aim of this analysis is to better understand the morphology and climatology
of ionospheric irregularities in our region. Interesting differences between the
north and south anomalies are noted when we examine the latitudinal–temporal
variation of irregularity activity. We investigate the possible causes of these
differences and note that variations in the irregularity seeding mechanism
and in the background ionosphere at the two anomalies could be important.
Phase screen diffraction theory is used to analyse our scintillation data and
we note problems with this theory for ray-paths with large off-zenith
angles. The height of the phase screen is another important issue. We discuss
the implications for models which rely on phase screen diffraction theory.
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