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VIIRS Day/Night Band observations of auroral activity during a 2015 severe geomagnetic storm

The Day/Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP represents a major advance in night time imaging capabilities. During geomagnetic storms, auroras can be observed by the DNB on the night side over both hemispheres. The radiometrically calibrated DNB observations can enable quantitative analysis of the spatial distribution and temporal evolution of aurora during geomagnetic storms. Two coronal mass ejections (CME) occurred on June 19 and 21, 2015 and had made their way to Earth to cause a G4 (severe) geomagnetic storm on June 22 afternoon. This paper presents an analysis of the radiance data from DNB observations of the aurora during the geomagnetic storm on June 22, 2015. Regions of aurora during each orbital pass are identified and the evolution of aurora is characterized with time series of the auroral boundary, area and total light emission of the aurora region in the DNB observation. The good correlation of aurora activities with ground geomagnetic index during the geomagnetic storm suggests that DNB observations of aurora can provide new details of the magnetospheric and ionospheric responses during severe geomagnetic storms.