A 15-Min Period Geomagnetic Pulsation Ps6 Excited by an Instability of Auroral Electrojets

Abstract

From a viewpoint of meandering of auroral arc, natural phenomena which are observed in space are compare with some laboratory experiments. A damped-type long-period magnetic pulsation that DAMPED-TYF£ 21hLT 2? 24 is observed during substorm both on the ground LONG-PERIOD-r-"1 and in the magnetosphere is called Ps6 according to the international classification of geomagne-tic pulsations. Six main morphological characteristics of Ps6 imply a strong relation with the meandering of auroral arc that is actually observed by a satellite in space and all-sky cameras on the ground. These observations derive the two-snake model on the three-dimensional dynamic structure of the current system in the magnetosphere-ionosphere that is set up associating with substorm. The model is named so, because the meandering of auroal electrojets is compared with the meandering of two snakes. The magnetic Ps6 and the associated meandering aurora are discussed in comparison with some laboratory experiments on meanderings of beam that were made by Webster, Cutler and Hallinan. Much more cooperative works among space physicists and laboratory experimentists are proposed to promote the comparative study.