Radio‐induced incoherent scatter ion line enhancements with wide altitude extents in the high‐latitude ionosphere

Apparent large electron density enhancements deduced from incoherent scatter radar observations during recent high power radio wave injection experiments at the European Incoherent Scatter Scientific Association (EISCAT) facility near Tromsø, Norway have been previously reported. These apparent enhancements extend over a wide altitude range, including the topside ionosphere. Observational evidence is presented, which shows that these apparent density enhancements appear to exhibit aspect‐sensitive backscattering and are not associated with corresponding changes in the frequency of the incoherent scatter plasma line. It is concluded that although an enhancement in the power of the incoherent scatter ion line is observed, it is not the result of an enhancement in the plasma density, but must be due to some other unknown mechanism.