• absorption in the F region at high latitudes;
  • linear mode conversion;
  • full-wave model

[1] The collisional/resonance absorption due to linear mode conversion of electromagnetic waves into electrostatic/plasma waves is studied in cold/warm magnetized plasmas relevant to the F-region of the high-latitude ionosphere. The absorption coefficient is calculated numerically using a full-wave model for high-frequency waves incident normally/obliquely to the direction of inhomogeneity. The absorption coefficient of collisional cold plasmas is found to be independent of the collision frequency in the small range of incidence angles near the critical angle; whereas, outside this range absorption increases with increasing collisions. In warm collisionless plasmas, the resonance absorption coefficient is shown to be independent of the electron temperature values pertinent to the F-region plasma. We have demonstrated for the first time a strong effect of the external magnetic field arbitrarily oriented in the plane of incidence on the absorption coefficient, which is not pronounced in the limit of weakly magnetized plasmas.