Figure 6.

Comparison of observed and calculated OH concentrations for high VOC environments. NO₂ and OH concentrations are normalized as explained in the text. Letters denote results from thirteen campaigns with hydrocarbon reactivity higher than 10 s⁻¹: (A) Amazonia averaged daytime and afternoon hours (2005); (B) Borneo (2008); (C) US deciduous forest (1998); (D1) Pearl River Delta (2006) morning and afternoon hours; (D2) Heshan (Pearl River Delta, 2014) morning and afternoon hours; (E1) Beijing (North China Plain, 2006) morning and afternoon hours; (F1) Mexico City (2003); (G) Tokyo (2004); (H) New York (2001); (F2) Mexico City (2006); (I) US ponderosa pine forest (2009); (E2) Wangdu (North China Plain, 2014) morning and afternoon hours; (E3) Huairou (North China Plain, 2016) morning and afternoon hours. Error bars denote stated accuracies. The light-blue shaded area denotes the range of model results for individual campaigns and the full white/blue line denotes the average of all model calculations. The thick dashed red line represents the new concept and the dotted red lines denote an error estimate of ±30%, which is a typical value for the observational constrained box model calculations of OH.