95th (top) and 50th percentile (bottom) summer O3 daily amplitude of all data available for 2011–2015 (please note that for Longmont (site 7) and Lyons (site 73) data are summer 2007 values). The marker size is a function of the amount of data which was used for the plot (see SM_Table_2). Please note the different color bar scales in the two graphs. DOI: https://doi.org/10.1525/elementa.300.f10