Fig. 6: The box plots of period-averaged components of GAM NO₂ modeling before, during, and after the Beijing Summer Olympics in 2008.

The GAM components, such as OMI NO₂, S(meteos), and S(non-meteos), are presented in a, b, and c, respectively. Within each box plot, the lower and upper bounds correspond to the 25th and 75th quartiles, while the solid line represents the median; the top and bottom whiskers extend from the hinges to the largest values by no more than 1.5* IQR (interquartile range) from the hinges. The mean values are noted by red square points with numbers. The black points outside the whisker are outliers