INITIAL RESPONSE AND COMPLEX POLAR-CAP STRUCTURES OF THE AURORA IN RESPONSE TO THE JANUARY 10, 1997 MAGNETIC CLOUD

On January 10(th), 1997, a magnetic cloud originating at the Sun was i ncident on the Earth. The initial disturbance to the magnetosphere, as reflected in the activities of the aurora, was measured by the Ultrav iolet Imager on the Polar Spacecraft. During this event we have observ ed the development of several unusual unique auroral forms that to our knowledge are unexplained in current models and theories. The observa tions were made on a global scale with unprecedented spatial and tempo ral resolution. The first activation of the aurora at local noon occur red within minutes of the arrival of the shock at 0107 UT. The substor m onset was observed at 0334 UT. During the intervening time significa nt polar cap precipitation occurred.