Reconnection between the interplanetary magnetic field and the Earth's magnetosphere applies the solar wind electric field to the magnetosphere, driving the processes collectively known as space weather. Processes internal to the magnetosphere, and thus the magnetospheric response to reconnection, can be modeled, but without an accurate model of the reconnection rate, the modeled magnetospheric response will be inaccurate. Fortunately, recent advances in ground-based radar monitoring of the ionosphere have enable remote sensing of the reconnection rate.

We present a statistical analysis of the response of the magnetic reconnection rate to the interplanetary electric field using the method of linear prediction filtering. The magnetic reconnection rate is calculated from Super Dual Auroral Radar Network (SuperDARN) measurements. The magnetic separatrix is identified as the offset circle (3° toward midnight from the magnetic pole) that best separates high spectral width (>150 m/s) backscatter, indicative of open magnetic field lines, from low spectral width backscatter. The electric field on the separatrix is determined from the best fit of the line-of-sight F-region plasma velocity to an eighth-order spherical harmonic function of ionospheric electrical potential. The reconnection rate is determined from the electric field component along the separatrix in the separatrix rest frame. We conclude that the magnetospheric response to a 1 mV/m step increase(decrease) in the y component of the interplanetary electric field (-VB_z) is as follows: there is a transient increase(decrease) in the reconnection potential due to the separatrix motion that reaches 2 kV after 12 min then returns to 0 kV after 28 min, and there is a sustained increase(decrease) in the reconnection potential due to ionospheric convection that reaches 5 kV after 25 min.