(a)–(d) The variation in the solar wind velocity (V), density (N), subsolar distance of the model magnetopause, dynamic pressure (Pd), SYM-H and ASYM-H during each Japan aurora event. The subsolar distance of the magnetopause was calculated using OMNI2 solar wind data using the model of Shue et al. (1998). Blue shaded regions denote modeled GMC events, green shaded regions denote observed GMC events by GOES satellites, and red shaded regions denote the time periods when red auroras were observed by citizen scientists in Japan. Red and blue bars describe the time interval of calculated median value of V, N and Pd described in Table 1.