Title: Field-aligned current observations in the polar cusp ionosphere
Abstract: Vector magnetic field measurements made during a sounding rocket flight in the polar cusp ionosphere show field fluctuations in the lower F region that are interpreted as being caused by the passage of the pay load through a structured field-aligned current system. The field-aligned currents have a characteristic horizontal scale size of about 1 km. Analysis of one large field fluctuation gives a current density of 10−4 A/m²