The ionosphere and troposphere affect GPS positioning in various ways. In particular, ionospheric scintillation, namely, extreme fluctuations in the ionosphere, is one of the causes of positioning failure with GPS. To improve the reliability of GPS positioning, we need to evaluate the infl uence of the ionosphere on GPS in polar regions.

    Japanese antarctic research activities began in the International Geophysical Year (IGY, 1957-1958). ENRI partici-pates in the Japanese Antarctic Research Expedition (JARE) to study the effect of the ionosphere and troposphere on GPS in high latitude regions.