Source and identification of heavy ions in the equatorial F layer

Abstract

Further evidence is presented to show that the interpretation of some Ogo 6 retarding potential analyzer (RPA) results in terms of ambient Fe+ ions is correct. The Fe+ ions are observed only within dip latitudes of ±30°, and the reason for this latitudinal specificity is discussed in terms of a low‐altitude source region and F region diffusion and electrodynamic drift. It is shown that the polarization field associated with the equatorial electrojet will raise ions to 160 km out of a chemical source region below 100 km but it will do so only in a narrow region centered on the dip equator. Subsequent vertical E × B drift, coupled with motions along the magnetic fields, can move the ions to greater heights and greater latitudes. There should be a resultant fountain of metallic ions rising near the equator that subsequently descends back to the E and D layers at tropical latitudes. Even if the metallic ions do have access to the lower F region at higher latitudes, the downward plasma flow at the F peak will restrict their access to the upper F region.