Weekday versus weekend diurnal variations in CO2 concentrations for each season.
Hourly mean CO2 concentrations ([CO2]) for weekday (red) versus weekends (grey) for (A) summer, (B) fall, and (C) winter. The bold line shows hourly means, and the shaded regions represent 95% confidence intervals. In the summer, weekday and weekend hourly averages are indistinguishable. In the fall and winter, weekday hourly averages are higher than weekend averages.