GEM: Particle Energization and Loss Associated with Magnetospheric Compression

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The solar wind exerts a pressure on the Earth's magnetosphere and rapid changes in the pressure can create a surprising variety of changes in the aurora. These changes can be observed on a global scale from satellites and the observations provide a powerful diagnostic tool for key aspects of the magnetospheric response to solar wind driving. Recent research has indicated that dramatic changes in the temperature of the plasma in the plasma sheet as well as dramatic changes in the width of the plasma sheet can occur on time scales of less than an hour. These changes are reflected in sudden changes in the nightside auroral luminosity. The project will use particle precipitation data from the Defense Meteorological Satellite Program (DMSP) satellites in conjunction with ultraviolet imager (UVI) image data from the Polar satellite along with particle and wave measurements from the Geotail satellite to study the auroral responses to solar wind dynamic pressure changes. Particular emphasis will be placed on the effects of abrupt pressure changes. The key scientific questions to be answered are: (1) Can the change in global auroral power in response to sharp pressure variations be predicted quantitatively, (2) what is the mechanism of magnetospheric particle energization and loss (through precipitation), (3) what are the magnetospheric source regions of the enhanced dawn/dusk aurora associated with such pressure events, and (4) what is the time sequence of auroral oval and polar cap response to pressure events?The data analysis will involve a large number of images and a large amount of the corresponding data from the DMSP and Geotail satellites. This data will be compiled into a database and will be added to the auroral data currently being served on-line by the Johns Hopkins University Applied Physics Laboratory Auroral Particles and Images Team.