(a) The keogram scanned along the North-South cross section as a function of scan angle from 15° North to 15° South from the 630.0 nm channel of the all-sky imaging photometer (ASIP) at Ny-Ålesund, January 13, 2013, 15–23 UT. Letters A–F mark six polar cap patches as they moved from north to south across the ASIP. The intensity is color coded according to the log (counts) scale on the right. (b) Phase scintillation indices recorded by the GPS scintillation monitor located at Ny-Ålesund, measurements from different satellites are color coded on the right. (c) Mean phase scintillations for all satellites averaged over 10 min. Shaded regions I–III denote enhanced scintillation events described in the text.