Laboratory Structure of the Magnetosphere Related to the Low Latitude Auroral Events.

Abstract

We have made an interpretation of the cause of low latitude aurora event based on our laboratory result of the magnetosphere. The latitudinal change of auroral oval for the different solar wind parameters is investigated. To confirm the validity of the scaling of the laboratory simulation, an analysis of satellite data of the magnetopause stand-off distance dependence on the IMF B, is used. The scaling of the magnetic field proved the exact scaling of the experimental IMF value to the real value. The latitude of auroral oval can be obtained from photographs by illumination. The latitude of auroral oval in the night region dependence on the IMF B, is obtained. The result shows that the auroral oval latitude of almost 50 degrees in the night region is obtained for B, = -10 nT. The other investigation is made for the latitudinal dependence of the auroral oval on the solar wind dynamic pressure. The result shows that the latitude becomes to be low when the dynamic pressure is high. During the change of dynamic pressure, other parameters such as B, are fixed. The result also indicates a possibility of the cause of low latitude aurora for northward IMF. The observed events shows, however, the necessity of the creation of high energy auroral particles. For this meaning, the condition to cause the low latitude aurora events is pointed out showing the important role of the absolute value and the temporal change of the solar wind dynamic pressure.