Characteristics of the upper‐air magnetic field and ionospheric currents are determined through an analysis of published rocket data on the magnetic scalar intensity. For the region between the earth's surface and theElayer of the ionosphere, the observed values are compared with values obtained by extrapolating the surface vector field. The agreement between the two sets of values is very good for equatorial flights but only fair for a flight at White Sands, New Mexico. The equatorial, ionospheric current density, which has a maximum of about 21 amp/km2, varies considerably with time and location of the rocket flight. The equatorial electro jet has a current intensity of about 130 amp/km and flows practically along the magnetic equator. Some of the computed currents associated with the normal magnetic daily variation are at variance with those expected from considerations, such as harmonic analysis, of the surface transient field and sheet‐current approximations. In the area around White Sands (geomagnetic latitude 41°N) a large negative magnetic anomaly exists that may contribute to the formation of the region of low intensity of radiation that lies between the two Van Allen radiation b