A short review on the F1-region ion composition in the auroral and polar ionosphere Original Research Article

Most F1 region ion composition measurements are obtained by the incoherent scatter technique. During magnetically quiet periods, we review all empirical models that have been obtained from EISCAT measurements. These models show comparable behaviour, which general trend is quite well described by the International Reference Ionosphere model. Specific attention is also given to the ion composition behaviour during magnetically active periods. The measurement problems are recalled. Measurements and simulations show that the molecular ions can dominate the F ionospheric layer when electric field are larger than 50 mV/m.