The polar ionosphere Original Research Article

Photometers monitoring oxygen night airglow emissions and a Canadian advanced digital ionosonde (CADI) have given a complementary view of the polar ionosphere over Eureka, Canada (80°N, 86°W) through each winter since 1991. The 630 nm [O] emission intensity, in particular, is seen to be directly proportional to the ƒoF2 critical frequency measured from the CADI. We report on the variations of these F-region parameters through the past solar cycle, drawing on observations from this site very near the north magnetic pole. [O] emission intensities even under quiet conditions are seen to vary over a factor of 10 or more through the solar cycle. During much of the time the airglow is enhanced by either polar auroras or F-layer patches (depending on the sign of the IMF Bz), each with their particular signatures. The extent and configuration of the polar cap, as a function of the Bz component of the IMF and the characteristics of the F-laver hatches within will be illustrated.