Synoptic distribution of dayside aurora: Multiple-wavelength all-sky observation at Yellow River Station in Ny-Alesund, Svalbard

Abstract Observations acquired from three-wavelength (427.8, 557.7 and 630.0 nm) all-sky imagers (ASIs) at Yellow River Station (YRS) in Ny-Alesund, 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 15 MLT “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 557.7 nm wavelength. The detailed dayside auroral spectra and morphology as a function of MLT are discussed.