Fig. 2: Responses of urban boundary layer, O3 and NOx to heatwaves.
From: Urban meteorology–chemistry coupling in compound heat–ozone extremes
a, The averaged backscattering coefficient (Bscat. coeff.) and PBLH from the ceilometer on normal days and heatwave days at the SORPES station in May–June 2023. b, Daytime evolution in O3 and NOx profiles from the morning (7:00–9:00 LT) to afternoon (12:00–16:00 LT). The solid lines represent mean values and shaded areas show the 25–75th percentiles. c, An isopleth diagram of daily maximum O3 against daytime NOx concentration and VOC reactivity. The circles indicate the mean value of NOx concentration and VOC reactivity at the surface on normal days (blue circle) and heatwave days (red circle). The squares represent the mean value of NOx concentration and VOC reactivity near 1,000 m and the error bars show ± 50% s.d. of VOC reactivity. There are 27 observation points for VOC observation near 1,000 m.
