Polar ionospheric responses to 4-times rapid turnings of the imf B z component-EISCAT/ESR radar observations

With the observations from EISCAT/ESR radar on Feb. 12 2003, the responses of polar ionosphere, especially those of the cusp/cleft region to the 4-times rapid turnings of IMF B-z component are investigated in this paper. During this event, latitudinal location of the cusp/cleft region was found moving back and forth, likely resulted from the variations of the reconnection sites at the magnetopause which are widely accepted to be ruled by the IMF polarity. Meanwhile, polar ionospheric plasma convection reversed several times, exhibiting strong correlation with the signs of the IMF B-z component. Correlative and timing analysis suggest that the dayside magnetosphere-ionosphere system seems to need an average reconfiguration time of approximate 3 minutes in response to the variations of the IMF polarity in polar region.