The occurrence region of the Earth’s aurora is mostly near the pole. The terrestrial aurora has a feature of emission band, which locates around geomagnetic latitude between 61 and 73 degrees. The appearance of the aurora is not in a stable form but changing with time. This study presents three periods of Earth’s auroral activity on April 28th, 2007, which was observed by the Visible Imaging System (VIS) cameras on board POLAR spacecraft. The image size is 256×256 pixels, which was taken in 12 second of exposure time during the Global Geospace Science (GGS) program. The analysis of auroral activity shows that the brightening zone of the auroral oval changes with various time scales. To compare with the model of auroral activity over the entire polar region, there are two characteristic phases around 2~3 hours, an expansive phase and a recovery phase (Akasofu, 1964). In addition, the solar wind data, which are interplanetary magnetic field (IMF), Earth’s magnetic field, solar wind plasma speed, and solar wind proton density will be used to determine the corresponding of auroral activity to solar wind dynamic in each phase. From this study, the various cases of terrestrial auroral activity will be presented.
Keywords: auroral activity, solar wind dynamics