Aurora-Associated Phenomena and the ePOP Mission

The enhanced polar outflow probe (ePOP) is the scientific part of the Canadian Space Environment small satellite “Cassiope” to be launched in the last quarter of 2007. The mission aims to study plasma and neutral outflows in the topside polar ionosphere (300—1500 km altitude), wave generation and particle interaction associated with these outflows and their effects on radio wave propagation. When compared to the energy involved in natural auroral phenomena, reaching sometimes up to hundreds of keV, the energy input into the ionosphere from ground-based powerful radio transmitters is much more modest, not exceeding 20 eV at the greatest. Even so, by transmitting powerful radiowaves into the ionosphere it is possible to reproduce some of the natural auroral phenomena, for example generation of artificial aurora,^{3- 5} Alfven waves,^6-8 plasma turbulence,^9,10 and ion outflow⁸ from the auroral F region. Two data sets presented show the similarity of some natural and radiowave-induced ion outflows from the auroral F region, accompanied by a strong electron (but not ion) temperature increase. Interpretive models supported by observations are given for red hydroxyl⁵ and green atomic oxygen⁴ radiowave-induced airglow (named artificial auroras⁴) recently discovered in the E-region.