Fig. 1.
Spatial patterns and time series of extreme thresholds. (A–C) 95th percentile of April–September 1999–2013. (A) MDA8 O3 (ppb). (B) 24-h average PM2.5 (μg m−3). (C) daily maximum temperature (°C). (D) Air stagnation frequency (% of days). (E) Annually derived 95th percentile of the quantities in A–D, indicated by blue, green, red, and black lines, respectively. Also shown are linear trends of 95th percentile (median) MDA8 O3 (ppb yr−1) and 24-h average PM2.5 (μg m−3 yr−1), along with interpair correlations of all quantities (MDA8 O3 and 24-h average PM2.5 trends removed).