Fig. 3
From: Response of aurora candidates in the Chinese official histories to the space climate during 511–1876
Number and percentage of aurora candidates of various colors in each month and season. The percentage is computed by aurora year counts in each month divided by the year counts of study periods. The percentages of the four seasons and the mean value (\(\overline{\mathrm{x} }\), solid lines) as well as it plus/minus the standard deviation (\(\overline{\mathrm{x} }\)±σ, dashed line) are denoted