Conjugate observations by the incoherent scatter radar at Sondrestrom, Greenland, and the Wideband Imaging Camera (WIC) on the IMAGE satellite have been used to establish a causal relationship between drifting F-region plasma structure in the polar ionosphere and upward ion number flux near the poleward edge of the auroral oval. A longitudinally extended patch of enhanced F-region density was observed as it advected equatorward across the open-closed field line boundary and into a region of discrete auroral rays and strong ion upflow (Vi > 800 m/s at 900 km altitude). Upward velocities within the upflow region remained constant during the patch transit, such that the upflowing number flux was directly controlled by F-region density (both increased by a factor of 2 within the patch). Because polar cap patches and ion upflows are both longitudinally extended, quasi-stable features of the nightside polar cap boundary, the observed interaction can produce a global-scale increase in plasma density at higher altitudes where suprathermal outflows are initiated.