The 4-emission-core structure of dayside aurora oval observed by all-sky imager at 557.7Â nm in Ny-Ã lesund, Svalbard

A survey of dayside aurora excitation at 557.7 nm, which was acquired from an all-sky imager at Yellow River Station in Ny-Ålesund, Svalbard, shows that there are 4 intense emission maxima in the dayside oval, centered near 0630/76, 0830/76, 1400/75, and 1600/75 (unit: MLT/MLAT), respectively. Tracing the magnetospheric sources of these cores along geomagnetic field lines, the 0830- and 1400-MLT cores correspond with the prenoon and postnoon magnetospheric boundary layers (MBLs), and the 0630- and 1600-MLT cores are located at the dusk and dawn MBLs, respectively. The potential solar wind-magnetosphere dynamic processes resulting in these auroral features are discussed.