Strong upwards transport of HONO in daytime over urban area of Beijing, China.

Strong upwards transport of Nitrous acid (HONO) in daytime over urban area of Beijing was observed based on combined observations of HONO, NOx (NO and NO2), nitrate, and PM at two heights (90 m and 528 m) on the highest building of Beijing (528 m above ground). The mean HONO at the 528 m (0.26 ppb) was lower than that at the 90 m (0.

High organic aerosol in the low layer over a rural site in the North China Plain (NCP): Observations based on large tethered balloon.

High mass concentration of organic aerosol (OA) and its fraction in PM (particle matter with radius <2.5 μm) were observed in the low layer over a rural site of the North China Plain (NCP) in winter 2018. The mass fraction of OA in PM was 65.

New positive feedback mechanism between boundary layer meteorology and secondary aerosol formation during severe haze events.

Severe haze events during which particulate matter (PM) increases quickly from tens to hundreds of microgram per cubic meter in 1-2 days frequently occur in China. Although it has been known that PM is influenced by complex interplays among emissions, meteorology, and physical and chemical processes, specific mechanisms remain elusive. Here, a new positive feedback mechanism between planetary boundary layer (PBL), relative humidity (RH), and secondary PM (SPM) formation is proposed based on a comprehensive field experiment and model simulation.