Efficient ion heating at high altitude, wave and temperature characteristics H. Nilsson (1), M. Waara (1), R. Slapak (1), M. André (2) (1) Swedish Institute of Space Physics, Kiruna (2) Swedish Institute of Space Physics, Uppsala In the high altitude cusp /mantle the oxygen ion perpendicular temperature increase with altitude in spite of the adiabatic cooling effect of the magnetic mirror field. This indicates transverse heating, presumably due to wave particle interaction. In an initial case study we searched for the longest period with significantly enhanced perpendicular to parallel temperature ratio, an expected sign of local transverse heating. It was found that the simultaneously observed waves could not explain the observed perpendicular ion temperatures. We now complement the initial study with a statistical study of the electric and magnetic field spectral densities in the frequency range below 1 Hz, in the general vicinity of the high altitude oxygen gyro frequency. This is further complemented with some new case studies, where we have picked out some of the cases with highest spectral density around the oxygen gyro frequency, in order to see if gyro resonance theory can explain the perpendicular ion temperatures observed in conjunction with the strongest observed wave activity. A preliminary finding is that ion temperatures are often isotropic in regions with strong wave activity, and the more pan-cake like distributions are observed when the wave activity ceases. We try to interpret this in terms of isotropic heating followed by a velocity filter effect.