Other sites

In the summer, an additional site was operated in Gucheng (39.2◦ N 115.7◦ E), Dingxing County, Hebei province.

This site, about 120 km to the south-west of central Beijing, is on one of the main high-pollutant transport pathways from the Hebei province to Beijing from the south-west.

The site is in a meteorological observatory surrounded by farm fields. The nearest town is about 10 km to the north-east.

The nearest road is 500 m to the north and the nearest village ∼ 1 km to the west. Several villages are located around the site.

In addition to the two highly instrumented urban (IAP) and rural (Pinggu) sites, 21 SNAQ (Sensor Network for Air Quality) boxes, which measure CO, NO, NO2, CO2, Ox , sizeresolved particulates (0.38–17.4 µm), temperature, relative humidity, wind speed and direction (Popoola et al., 2018), were deployed during the summer and winter campaigns across the urban and rural areas of Beijing to map air pollutant variations.

Six additional SNAQ boxes were deployed at six different heights (8, 32, 102, 160, 260 and 320 m) on the IAP tower from 9 to 23 November 2016 and 25 January to 31 December 2017.