Iron atoms and metallic species in the Earth's upper atmosphere

Resonant lidar detection of iron atoms have been performed at the Observatoire de Haute Provence (France) during 4 nights in november 1986 and in april 1987. The average iron atoms abundance is 3.6 × 10 9 cm −2 in november, and 2.6 × 10 9− cm −2 in april. Iron atoms density profiles are compared to the atomic sodium ones, obtained simultaneously by lidar and indicating an average sodium abundance of 4 × 10 9 cm −2 . The relative abundance of the sum of the atomic and ionic forms is compared for several metallic species with their abundance ratios in the incoming meteorites. Finally, similar comparisons using lidar and mass spectrometer data are made for the ratio of the atomic and the ionic forms in the atmosphere.