Budget of the OH reactivity in the North China Plain in summer- and wintertime: Results from recent field campaigns

Two comprehensive field campaigns were conducted in the densely populated North China Plain in summer 2014 and winter 2016. In 2014, the measurement site was located in a botanic garden close to the smaller town of Wangdu without major industry, but influenced by regional transportation of air pollution. In 2016, measurements were done close to Beijing and this site was partly impacted by wintertime pollution events. The loss rate coefficient of atmospheric hydroxyl radicals (OH) was quantified by direct measurements of the OH reactivity. Concurrent measurements of OH reactants allow for the determination of calculated OH reactivity. The comparison between measured and calculated OH reactivity can be used to quantify the fraction of missing OH reactivity. Closure of OH reactivity in these campaigns for different seasons will be investigated and compared with results from previous campaigns in China.