OBSERVATIONS AND MODELING OF CORRELATED PI-B MAGNETIC AND AURORAL LUMINOSITY PULSATIONS

A comparison of observations of Pi B magnetic pulsations at the ground with wide-angle photometer measurements of the accompanying auroral l uminosity fluctuations has found several cases of well-correlated magn etic and optical pulsations, with periods in the range 15-50 s. This f inding strongly suggests that precipitation fluctuations drive at leas t some of those components of the Pi B signal with periods in this ran ge. We found no luminosity fluctuations associated with the 3-s enhanc ement of Pi B pulsations. We modeled the magnetic perturbation under a patch of enhanced E region conductivity as it drifts or as its conduc tivity changes, for circular and strip patch shapes. These idealized m odels can reproduce some features of the Pi B signature. Most notably, a monotonic variation in the model parameters can produce a reversal in the sense of polarization rotation. A moderate enhancement in the c onductivity of a 1-km-wide strip can produce magnetic perturbations wi th amplitudes typical of Pi B pulsations.