This dataset contains atmospheric nitrous acid (HONO) measurements made at the IAP-Beijing site during the summer and winter APHH-Beijing campaign for the Atmospheric Pollution & Human Health in a Chinese Megacity (APHH) programme. HONO data was obtained using a commercial (QUMA) Long Path Absorption Photometer (LOPAP) instrument and calibrated using liquid nitrite standards. Data are averaged over 5 mins, the time stamp represents the start time of each averaging period. Missing data are either due to baseline measurements, calibrations or instrument malfunction. They are not retrievable.

This dataset contains atmospheric nitrous acid (HONO) combined measurements made at the Institute of Atmospheric Physics land station (IAP-Beijing) site, during the summer and winter APHH-Beijing campaign for the Atmospheric Pollution & Human Health in a Chinese Megacity (APHH) programme. This combined dataset consists of a single mean time series of HONO mixing ratio (ppb), and associated min/max values determined from the datasets of 4 instruments that measured HONO at IAP at ground level. The data are averaged over 1 hour, the time stamp represents the start time of each averaging period. The instruments included in the combined dataset are the University of Birmingham commercial wet-chemical LOPAP instrument (Heland et al. 2001), Institute of Chemistry, Chinese Academy of Sciences custom built wet-chemical instrument (Tong et al. 2016), and two custom built Broadband Cavity Enhanced Spectrophotmeters (BBCEAS) from the University of Cambridge (Kennedy et al. 2011) and Anhui Institute of Optics and Fine Mechanics (Duan et al. 2018).

Chemistry of the Antarctic Boundary Layer and the Interface with Snow (CHABLIS) is a Natural Environment Research Council (NERC) and Antarctic Funding Initiative (AFI) funded project, aimed at studying the chemistry of the Antarctic Boundary Layer in greater detail, and for a longer duration, than has previously been attempted. Field measurements were carried out at the British Antarctic Survey station, Halley, at the Clean Air Sector Laboratory (CASLab). Year-round measurements began in February 2004, and a summer campaign focussing on oxidants ran during January/February 2005, after which CHABLIS fieldwork ended. The dataset contains HONO mixing ratio (nitrous acid) measurements. Access to this dataset is now public.