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Abstract: Observations acquired from three-wavelength (427.8, 557.7 and 630.0nm) all-sky imagers (ASIs) at Yellow River Station (YRS) in Ny-Ålesund, Svalbard, are used to examine the synoptic distribution of dayside aurora. The results demonstrate that the maximum emission regions (MERs) at each wavelength are all located in the postnoon sector, but have rather different magnetic local time (MLT) distributions from each other. The so-called 15MLT “hot spot” is the overlapping region of the MERs at three wavelengths, and the prenoon “warm spot” is characterized uniquely by an increase of emissions at the 557.7nm wavelength. The detailed dayside auroral spectra and morphology as a function of MLT are discussed. [Copyright &y& Elsevier]

Abstract: A survey of dayside aurora excitation at 557.7nm, 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. [Copyright &y& Elsevier]