Convective response to a transient increase in dayside reconnection

Measurements with five of the northern hemisphere Super Dual Auroral Radar Network (SuperDARN) radars have yielded a detailed temporal and spatial view of the evolution of a dayside convection enhancement, which we associate with a transient increase in dayside reconnection. The convection enhancement was located in and immediately poleward of the ionospheric footprint of the cusp. During the enhancement, both the cusp and the region of enhanced flow shifted equatorward by ∼2°. As the flow enhancement diminished, the cusp footprint moved poleward to its original position. The entire event had a duration of ∼18 min and was associated with a transient 29 kV increase in the cross polar cap potential. We estimate that ∼3.2×107 Wb of magnetic flux was opened at the dayside magnetopause during the most active 12 min of this event. The length of the reconnection line on the dayside magnetopause is estimated to have reached 19,000 km. The characteristics of the dayside ionospheric response are very similar to those predicted by Cowley and Lockwood [1992] in their expanding and contracting polar cap model. These are the first observations that have provided an extended spatial and temporal view of the responses of dayside convection and the cusp to a transient reconnection event.